4 Animal Kingdom

 

CHAPTER NO.4 ANIMAL KINGDOM

 

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INTRODUCTION:About 7.77 Millions of species of animals have been described which show a great diversity of life. It becomes more necessary to classify them to assign a systematic position. Despite the fact that a bewildering variety of species with different structures and forms exist out there, organisms share some common

features among themselves. These similarities are the basis of classification.Thus classification is the action of classifying the animals based on similar characteristics for easy identification and study. A biological classification generally pins out the morphological and evolutionary similarities as its basis. The basis

of classification can vary according to the purpose of the classification. Let's go on the basis of classification of the animal kingdom in detail.

 

WHY IT IS NECESSARY TO CLASSIFY ORGANISMS?

Classification helps in the identification of living organisms as well as in understanding the diversity of living organisms better.

Classification helps us to learn about different kinds of plants and animals,their features, similarities and differences.

It enables us to understand how complex organisms evolve from simpler

organisms.To understand and study the features, similarities and differences between different living organisms, they are grouped under different categories.The classification also helps in assigning a systematic position to newly described species.

 

ANIMAL KINGDOM AND ITS CLASSIFICATION:The animal kingdomis the largest kingdom amongst the five kingdoms consisting of all animals. Animals are multicellular eukaryotes; do not possess a cell wall or chlorophyll like plants, and share the same mode of nutrition, that is, the heterotrophic mode. Besides these similarities, they are also related to their cell arrangement, body symmetry, the level of organization, coelom, presence/absence of notochord, etc. Based on these features, the animal kingdom has been classified into 11 different phyla.Animal evolution began in the ocean over 600 million years ago with tiny creatures that probably do not resemble any living organism today. Since then,animals have evolved into a highly-diverse kingdom. Although over one million extant (currently living) species of animals have been identified, scientists are continually discovering more species as they explore ecosystems around the

world. The number of extant ( Still Alive) species is estimated to be between 3 and 30 million. Scientists predict that only 15% of the species are known to man from the estimated 8.7 million species. That leaves almost 85% species yet to be discovered. Only about 953,434 species of animals have been catalogued in the animal kingdom. There are some which are even yet to be discovered. Animals vary in complexity so scientists are faced with the difficult task of

classifying them within a unified system. They must identify traits that are common to all animals as well as traits that can be used to distinguish among related groups of animals. It is essential to understand the interrelationships among the different groups of organisms. Classification is a tool which helps us to deal with a great diversity of living forms.The animal classification system characterizes animals based on their anatomy,morphology, evolutionary history, features of embryological development, and genetic makeup. This classification scheme is constantly developing as new

information about species arises. Understanding and classifying the great variety of living species help us better understand how to conserve the diversity of life on earth. The different criteria for animal classification are explained below.

 

BASIS OF CLASSIFICATION OF ANIMAL KINGDOM:There are a few important characteristics that are regular to different organisms.

Therefore, it is important for us to know about the various components.Classification of Animal Kingdom is based on various fundamental features like:

 

1. Level of Organization

2. Body Symmetry

3. Diploblastic and Triploblastic Organization

4. Coelom development

5. Segmentation of the body

6. Presence or absence of Notochord

7. Patterns of circulatory, digestive and reproductive frameworks

 

Now we will look at these components in details:LEVEL OF ORGANISATION:

 

Although all members of Animalia are multicellular, all of them do not

exhibit the same pattern of organisation of cells. Example: in sporices, the cells are arranged as loose cell aggregates, i.e., they exhibit cellular level of organisation. Some division of labour (activities) occur among the cells In coelenterates, the arrangement of cells is more. ~~. Here the cells performing the same function are , hence is called tissue level of organization.

 

A still higher level of organisation, i.e., organ level (organ level of organization) is exhibited by members of and other higher phyla where tissues are grouped together to form organs, each specialised for a particular function. In animals like Annelids, Arthropods, Molluscs, Echinoderms and Chordates, organs have associated to form functional systems, each system concerned with a specific physiological function. This pattern is called organ system level of organization.

 Organ systems in different groups of animals exhibit various patterns of complexities For example, the digestive system in Platyhelminthes (incomplete digestive system) has only a single opening to the outside of the body that serves as both mouth and anus, and is hence called incomplete.A complete digestive system has two openings, mouth and anus.Similarly, the circulatory system may be of two types: open type in which the blood is pumped out of the heart and the cells and tissues are directly bathed in it and closed type in which the blood is circulated through a series of vessels of varying diameters (arteries, veins and capillaries).

 

SYMMETRY:We can categorize animals on the basis of the symmetry of their body. The course of action of body parts around a main line or point decides the symmetry. Sponges are mostly asymmetrical, i.e., any plane that passes through the centre does not divide them into equal halves.When any plane passing through the central axis of the body divides the organism into two identical halves, it is called radial symmetry.Coelenterates, Ctenophores and Echinoderms have this kind of body plan.Animals like Annelids, Arthropods, etc., where the body can be divided into identical left and right halves in only one plane, exhibit bilateral symmetry.

DIPLOBLASTIC AND TRIPLOBLASTIC ORGANISATION

Animals in which the cells are arranged in two embryonic layers, an external ectoderm and an internal endoderm are called diploblastic animals, e.g.,

 

The animals in which the body cavity is absent are called acoelomates,

e.g., Platyhelminthes, Nematodes.

SEGMENTATION:In some animals, the body is externally and internally divided into segments with a serial repetition of at least some organs. For example, in earthworm,the body shows this pattern called metameric segmentation and the phenomenon is known as metamerism .

Metamerism is conspicuous both externally and internally in annelids, is mostly external with arthropods, and mainly internal in man and other chordates (vertebrae, body muscles, some blood vessels, and nerves).

 

NOTOCHORD:Chordates are the animals with a notochord. On the other hand, non-chordates are the animals lacking a notochord.

Notochord is a mesodermally [the middle layer of cells or tissues of an embryo, or the parts derived from this (e.g. cartilage, muscles, and bone)] derived rod-like structure formed on the dorsal side [posterior] during embryonic development in some animals.

Animals with notochord are called chordates and those animals which do

not form this structure are called non-chordates, e.g., Porifera to

Echinoderms.

 

LET US KNOW WHAT WE HAVELEARNT!

PART:A VERY SHORT ANSWER QUESTIONS:-

a) MULTIPLE CHOICE QUESTIONS:-

 

1. Identify the characteristic of acoelomates

a) Absence of mesoderm

b) Absence of brain

c) Coelom that is incompletely lined with a mesoderm

d) Solid body without a cavity surrounding internal organs

 

2. Radial symmetry is found in which of the following phylums?

a ) Coelenterata and Platyhelminthes

b) Coelenterata and Echinodermata

c) Arthropoda and Mollusca

d) Porifera and Coelenterata

 

3. Following is a Diploblastic animal:

(a) Coelenterata

(b) Platynelminthes

(c) Nematahelminthes

(d) Arthropods

 

4. Which part is originated from the mesoderm?

(a) Coelom

(b) body cavity

(c ) notochord

(d) All

 

5. Which one of the following phylum is characterized by absence of

coelom?

(a) Annelida

(b) Mollusca

(c) Echinodermata

(d) Platynelminthes

 

 

b) FILL IN THE BLANKS:-

1. ——————— is apseudocoelomate animal.

2. Radial symmetry means that the body of animal may be divided

into equal halves.

3. Animals with three primary germinal layers are referred to as

 

c) TRUE/ FALSE

1. Porifera has organ level of organisation.

2. Echinoderms possess radial symmetry.

3. Platyhelminthes has incomplete digestive system.

 

ANSWER KEY: PART-A

a) Multiple choice Questions:-

 

1.(d) Solid body without a cavity surrounding internal organs

2. (b) Coelenterata and Echinodermata

3. (a) Coelenterata

4. (d) All

5. d) Platyhelminthes

 

b) Fill in the blanks:-

1. Platyhelminthes or Nematodes

2. Two

3. Triploblastic

 

c) True or False:-

1. False

2. True

3. True

 

B) SHORT ANSWER TYPE QUESTIONS:-

1. Why classifying the organisms is important?

2. What are diploblastic animals?

3. Define true coelom. Give Example of phylums showing true Coelom.

 

C) LONG ANSWER TYPE QUESTION:-

1. Give account detail of basis of animal classification.

 

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INTRODUCTION:BASIS OF CLASSIFICATION

In spite of differences in structure and form of different animals, there are fundamental features common to various individuals in relation to the arrangement of cells, body symmetry, nature of coelom, patterns of digestive, circulatory or reproductive systems. These features are used as the basis of animal classification and some of them are discussed here:

 

1) LEVELS OF ORGANISATION: -Four levels of organisation are found in anunats.

Celluiai Level: In case of cellular level organization, a single cell is responsible for all the metabolic activities. Cellular level organization is present in unicellular animals and some of the muciticellular animals e.g. Sponges.Tissue Lever ln case of tissue level organization, a group of cells is responsible for all the metabolic activities, e.g. coelenterates.

 

Grgan Level: In case of organ level organization, some specialized organs are present for some specific functions, e.g. Platyhelminthes.

 

Graan System Level: In organ system level organization, complex organ

systems are present for various functions, e.g. mollusca, chordate.

 

2) Symmetry: - Some of the animals are almost asymmetrical. Their body

cannot be divided into two equal halves from any plane, e.g. sponges. Radial Symmetry: In case of radial symmetry, any plane passing through the N central axis divides the body into two identical halves, e.g. coelenterates,ctenophores, echinoderms, etc. Bilateral Symmetry: In case of bilateral symmetry, the body can be divided into two identical halves only through a single plane, e.g. annelida, arthropoda, etc.

 

3) Diploblastic and Triploblastic Organisation When the cells are arranged in two embryonic layers, the animal is called a

diploblastic animal. The two layers are; ectoderm and endoderm. Mesoglea; which is an undifferentiated layer is present between the ectoderm and endoderm. Example: coelenterates. When the cells are arranged in three embryonic layers, the animal is called triploblastic animal. The three layers are; ectoderm, mesoderm and endoderm. Examples: Platyhelminthes to chordates.

 

4) Coelom: - The body cavity; which is lined by mesoderm is called

coelom.Coelomates: If coelom is present, the animal is called coelomate, e.g. annelids, molluscs, arthropods, echnioderms, hemichordates and chordates.

 

Pseudoceolomates: If the body cavity is not lined by mesoderm but the

mesoderm is present as scattered pouches in between the ectoderm and

endoderm, the animal is called pseudocoelomate, e.g. aschelminthes.

Acoelomates: When the body cavity is absent, the animal is called

acoelomate, e.g. platyhelminthes.

 

5) Segmentation: - The body of some animals is externally and internally divided into segments with serial repetition of at least some organs. For example; the body of the earthworm shows metameric segmentation. This phenomenon is called metamerism.

 

6) Notochord: - Notochord is a mesodermally derived rod-like structure. It is formed on the dorsal side during embryonic development in some animals. If notochord is present then the animal comes under chordates. =" snros:Whooutpotoccwoard is of ec nonechorcdate 2 cf cofars to echinoderms,

 

7) Body Plan: - Animals have three basic body plan as given below:

Cell aggregate body plan: Cells are loosely arranged and do not organize to form tissues, e.g., Sponges.Blind sac body plan: has a cavity that helps in digestion with a single opening, the mouth, e.g., Coelenterates.Tube within tube body plan: It is found in higher animal groups from nematodes to chordates. The body consists of two openings i.e., one for ingestion and one for egestion.

 

8) Body Support and Protection:-Soft-bodied animals: The animals which are simpler and primitive, do not have a hard cover or support for the body. They do not have an external or internal skelton.

 

Hard bodied: The higher animals have a hard protective material in the form of skelton either outside (Exoskelton) or inside the body ( Endoskelton).

 

2. CLASSIFICATION OF ANIMALS:-A broad classification of animlas based on common fundamental features is given below:-

Kingdom animalia have been grouped into two main categories depending

on the presence or absence of notochord as given in the flow chart below:

 

LET US KNOW WHAT WE HAVE LEARNT!

A) VERY SHORT ANSWER TYPE QUESTIONS:-

a) Multiple choice Questions:-

 

1) In sponges level of organisation is:

a) cellular

b) tissue

c) organ

d) organ system

 

2) levels of organisation are found in animals:

a) three

b) four

c) two

d) several

 

3) When the body cavity is absent, the animal is called:

a) mixocoelomate

b) coelomate

c) pseudocoelomate

d) acoelomate

 

4) When the cells are arranged in two embryonic layers, the animal

is called:

a) diploblastic

b) triploblastic

c) asymmetrical

d) radially symmetrical

 

b) True or False:-

1) If coelom is present, the animal is called coelomate.

2) Platyhelminthes have tissue level organization.

 

 

c) Fill in the blanks:-

1) is amesodermally derived rod-like structure.

2) When the body cavity is absent, the animal is called .

3) The body of the earthworm shows segmentation.

 

ANSWER KEY: PART- A

A) VERY SHORT ANSWER TYPE QUESTIONS:-

a) Multiple choice Questions:-

 

1. a) cellular

2. b) four

3. d) acoelomate

4. a) diploblastic

 

 

b) True or False:-

1. True

2. False: Platyhelminthes has Organ System level of organisation.

 

c) Fill in the blanks:-

1. Notochord

2. Acoelomate

3. Metameric

 

B) SHORT ANSWER QUESTIONS: -

1) What are diploblastic animals? Name two layers.

2) Define Notochord. Name various types of body plans.

3) What is segmentation?

 

C) LONG ANSWER QUESTION:-

1) Explain in detail basis of animal classification.

2) Graphically explain classification of kingdom animalia.

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INTRODUCTION:Animal kingdom is broadly classified into following phylas based on few aspects.

 

LEVELS OF ORGANISATION: - Under cellular level of body plan only phylum porifera finds its place. Phylas above porifera in the heirarchy have tissue and higher levels of organisation.

 

SYMMETRY: Cellular level body organisation has no symmetry. So, poriferans are asymmetric. Radial symmetry includes phylum cnidaria and phylCtenophora.Bilaterally symmetrical animals are further classified based on coelom. Phylum Platyhelminthes have false coelom so called pseudocoelomates. Phylum Annelida,Arthropoda, Mollusca, Echinodermata of non chordates; Phylum hemichordata and

Phylum chordata all have true coelom so called Coelomates.

PHYLUM PORIFERA (Sponges; pore bearing animals)

 

Habitat:- Mostly found in marine water and are sedentary. Exception to

marine habitat is spongilla ( fresn water sponge).

 

Level of Organization:- These have cellular level of organisation; are

diploblastic and asymmetric animals.

 

Body wall:- consist of two layers: outer dermal/ pinacoderm having

pinacocytes , inner choanoderm having choanocytes/ collar cells.

There is a gelatinous non cellular layer called mesenchyme/ mesoglea which has free amoebocytes.Power of regeneration is great due to presence of totipotent cells called archeocytes in gemmules.

The body is perforated by numerous minute pores called Ostia ( analogous to mouth) all of which open into a large cavity called spongocoel. The spongocoel opens to outside through osculum ( analogous to anus). Water enters the body through Ostia then into spongocoel and leaves through osculum.

 

Digestion:- In intracellular and are omnivorous having holozoic nutrition mode.

 

Respiration and excretion:- occur by diffusion through general body

surface. These are ammonotelic

 

Endoskeleton:- is made up of calcareous spicules or siliceous spicules and spongin fibers.

 

Canal System:- These have peculiar canal system. Water current flows

through canal system and help in nutrition, respiration, excretion and

reproduction

 

All sponges are hermaphrodite; reproduction takes place by fragmentation,or external budding. Sometimes it occurs by internal buds called gemmules.Development is indirect including Larval stage called amphiblastula

 

Some Representative animals:Scypha (Sycon)

Spongilla (Fresh water sponge)

 

Eusphongia (bath sponge):- The skeleton is used for bathing and washing automobiles. Fupuctela (Venus flower basket):- Given as a precious marriage gift in Japan.

 

A) VERY SHORT ANSWER QUESTIONS:-

a) MULTIPLE CHOICE QUESTIONS:-

 

1. The digestion of food in sponges is:

a) Extracellular

b) Intracellular

c) Both Extracellular & Intracellular

d) Absent

 

2. In poriferans, the rudimentary division of labour in present between:

a) Cells

b) Tissues

c) Organs

d) Organ-syste

 

3. The internal buds of fresh water sponges are otherwise called

a) Choanoucyte

b)Gemmule

c) Osculum

d) Gastrula

 

4. is the name of dried skeleton of ‘Venus flower basket’

a) Euplectella

b) Euspongia

c) Leucosolenia

d) Spongilla

 

5. Larval stage in development of Poriferans in

a) Planula

b) Maggots

c) Amphiblastula

d) Cydipid

 

b) TRUE OR FALSE:-

1. Phylum Platyheimiuthes are called Presudocoelomates

2. The majority of sponges are sedentary.

3. Hydra belongs to Phylum Porifera.

 

c) FILL IN THE BLANKS:-

1. The precious marriage gift in Japan is

2. Some sponges have soft fibres of a protean as an endoskeleton

 

a) MULTIPLE CHOICE QUESTIONS:-

1. b) Intracellular

2. a) Cells

3. b) Gemmules

4. a) Euplectella- The skeleton of these is given as a precious gift in marriages in Japan

5. c) Amphiblastula

 

b) TRUE / FALSE:-

1. False. Phylum Platyhelminthes are called acoelonates

2. True

3. False. Sycon, Spongilla belong to phylum Porifera.

 

c) FILL IN THE BLANKS:-

1. Euplectella

2. Spongin

 

B) SHORT ANSWER TYPE QUESTIONS:-

1. What is spongocoel?

2. Mention two functions of canal system in sponges.

3. What are gemmules?

 

C) LONG ANSWER TYPE QUESITON:-

1. Enlist some characteristics of phylum Porifera.

2. Write a note on canal system of Poriferans.

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INTRODUCTION:COELENTERON, the gastro vascular cavity is present in coelenterata.CNIDOBLASTS containing stinging cells are present, so also known as cnidaria.

 

CHARATERISTICS OF COELENTERATA:

Habitat: All are aquatic, mostly marine except Hydra.

Symmetry : Radially symmetrical These are diploblastic animals with tissue level organisation and blind sac body plan.

The name Cnidaria is derived from Cnidoblasts/Cnidocytes, which contain stinging cells or nematocysts present on body and tentacles and help in anchorage, defence and capturing of prey.The body wall is two layered - outer epidermis and inner gastrodermis with a non cellular mesoglea layer in between. These are carnivorous and have holozoic mode of nutrition. Coelenteron has single opening mouth or hypostome for both ingestion and egestion. Digestion is both intracellular and extracellular.

Respiration and excretion occur through general body surface. These are ammonotellic.These have diffused nervous system comprising of network of nerve cells. Brain is absent.Cnidarians exhibit two basic body plan - polyp and medusa.Polyp is sessile, fixed and cylindrical. e.g. Hydra, Adamsia Medusa is umbrella like and free swimming e.g. Aurelia.Cnidarians which exist in both forms exhibit alternation of generation or metagenesis.

Coelentrates show asexual reproduction by budding anc [as a Development is indirect and there are two larval forms : Planufa in ebelia and Some Representative Animals :

Physalia (Portugese Man of war)

Obelia ( Sea fur)

Aurelia ( Jelly fish)

Hydra ( Fresh water sponge)

Adamsia ( Sea anemone)

Corallium ( Precious red coral)

 A coral reef is a ridge in the sea and is formed of skeletons of

coelenterates called corals. It is mainly formed of calcium carbonate.

 

LET US KNOW WHAT WE HAVE LEARNT?

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

A)MULTIPLE CHOICE QUESTIONS :

 

1. Tentacles of hydra help in:

a) Locomotion

b) Food capturing

c) Both a and b

d) None of these

 

2. Nematocysts are organs of:

a) Sensation

b) Reproduction

c) Defence and offence

d) Respiration

 

3. Pick the most suitable terminology to relate to life cycle of obelia:

a) Neoteny

b) Metamorphosis

c) Metagenesis

d) None of above

 

4. The cavity of cnidarians is called:

a) spongocoel.

b) gastrovascular cavity

c) haemocoel.

d) none of these

 

5. The characteristic of cnidarians is:

a) Mesoglea.

b) pedal disc

c) Manudrium.

d) Nematocysts

 

B) TRUE/ FALSE

1. Cnidarians are characterized by stinging spicules.

2. Both sponges and cnidarians exhibit a tissue level of organisation.

3. Aurelia is a fresh water polyp.

 

C) FILL UPS :

1. is an important precious coral .

2. Cnidarians are called so because of presence of cells.

 

ANSWER KEY: PART-A

A)MCQ'S:-

 

1. (c) Tentacles of hydra help both in locomotion and food capturing.

2. (c) defence and offence

3. (b) metagenesis: Exist in both forms, polyp and medusa and show alternation of generation.

4. (b) gastrovascular cavity or coelenteron

5. (d) Nematocysts

 

B)TRUE/ FALSE:-

1. True: present in cnidoblasts as defensive mechanism.

2. False: Sponges have cell aggregate level and Cnidarians have

tissue level of organisation.

3. False: Aurelia is coastal water medusa.

 

C)FILL UPS:-

1. Corallium

2. Cnidoblasts.

 

PART:B SHORT ANSWER TYPE QUESTIONS :

1. What are cnidoblasts? Give their functions.

2. Why Physalia is called Portugese man of war?

3. What is metagenesis? Mention one example which exhibit this phenomenon.

4. Why is coelenteron called gastrovascular cavity?

 

PART:C LONG ANSWER TYPE QUESTIONS:

1. List some peculiar features of phylum Cnidaria.

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INTRODUCTION:PHYLUM CTENOPHORA (The Comb Jellies a Sea Wallnuts)

(Gk. Ktene- comb, phors- bearing)The ctenophores as a distinct group were first recognized by Escscholtz (1829).

 

General Characters:-There are about 50 species of ctenophores.These are commonly called sea walnuts or comb jellies.

 

1. Habitat: These are exclusively marine & solitary.

2. These are diploblastic with tissue level of organization and are radially symmetrical.

 

3. Locomotion: Locomotion is by ciliary movements of a vertically arranged comb plates so commonly called comb-jellies/sea walnuts.

 

4. Body appendages: These generally have one pair of solid tentacles which have special adhesive cells called collobiasts / lasso celis, which help in food capturing.

 

5. These have complete alimentary canal, digestion is intercellular and extracellular.

 

6. Excretion and respiration: Exertion and respiration occurs through body surface. These are ammonotelic, secretes ammonia as excretory product.

 

7. Nervous system: Nervous system is diffused; peculiar sense organ is

statocyst which helps in equilibrium.

 

8. Bioluminescence is well marked

 

9. Reproduction: Reproduction is only sexual; these are hermaphrodite.

Development is indirect through a larval stage called CYDIPID larva.

SOME REPRESENTATIVE ANIMALS:

 

PART: A VERY SHORT ANSWER QUESTIONS:-

a) MULTIPLE CHOICE QUESTIONS:-

 

1. Biradial symmetry and lack of cnidoblasts are the characteristics of:

a) Starfisn and sea anemone

b) Aurelia and Paramecium

c) Ctenoplana and Beroe

d) Hydra and starfish

 

2. Bioluminescence is a characteristic of:

a) Ctenoplana

b) Beroe

c) Sea-gooseberry

d) All of above

 

3. Ctenophorans are commonly refered to as:

a) Flatworms

b) combjellies

c) seaanemone

d) cnidarian

 

4. The number of ciliated rows present in comb jellies are:

a)8

b)6

c)4

d)9

 

b) TRUE O/FALSE:-

1. Ctenophores are bioluminescent, predators and most are

transparent.

2. Ctenophores have alternation of generations.

3. Ctenophores have bilateral symmetry.

 

C) FILL IN THE BLANKS :

1. When a cnidarian catches prey, it uses stinging cells called

2. Special adhesive cells on tentacles are called .

 

ANSWER KEY: PART-A

A) VERY SHORT ANSWER TYPE QUESTIONS:-

a) MULTIPLE CHOICE QUESTIONS:-

 

1. (c) Ctenoplana and Beroe

2. (d) All the above

3. (b) Comb jellies

4. (a)8

 

b) TRUE OR FALSE:-

1. True

2. False

3. False: It is RADIAL but due to occurrence of two lateral tentacles in some comb jellies it becomes BIRADIAL.

 

C) FILL IN THE BLANKS:-

1. Cnidoblasts

2. Coloblasts

 

B) SHORT ANSWER TYPE QUESTIONS:-

1. Why phylum Ctenophora is called phylum of comb jellies?

2. What is statocyst?

3. Name the adhesive cells used in locomotion by Ctenophora members.

 

C) LONG ANSWER TYPE QUESTIONS:-

1. Enlist some characteristics of phylum Ctenophora.

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INTRODUCTION:PLATYHELMINTHES:Platyhelmnithes is a phylum of dorsoventrally flattened, acoelemate but triploblastic animals having bilateral symmetry and blind sac body plan. Due to their flattened nature, they are also called FLAT WORMS.The term platyhelminthes was coined by Gagenbaur (1859).CHARACTERISTICS OF PLATYHELMINTHES:

 

1. HABITAT:- Both free living and parasitic forms occur in the phylum. Free living flat worms are terrestrial as well as aquatic.

 

2. BODY FORM:- Body is dorsoventrally flattened, leaf like or ribbon like.

 

3. SYMMETRY:- Flat worms possess bilateral symmetry.

 

4. BODY PLAN-- Blind sac plan i.e. there is a single aperture for mouth and anus.

 

 

5. GERM LAYERS:- They are triploblastic animals with three germ layers-ectoderm, endoderm, mesoderm.

 

6. LEVEL OF ORGANISATION:- It is primitive organ level of organisation.

 

7. COELOM:- A coelom is absent i.e. flat worms are acoelomates.

 

8. SEGMENTATION:- True segmentation is absent.

 

9. CEPHALISATION:- A definite head appears for the first time in platy

helminthes. The head contains sensory organs.

 

10. SKELETON:-A skeleton system is absent. In certain cares scleroprotien cuticle is present.

 

11. APPENDAGES:. Absent. Endoparasites possess hooks and suckers for

attachment.

 

12. DIGESTIVE SYSTEM:. Digestive tract is incomplete due to blind sac body plan. Digestive system is absent in parasites like tapeworm.

 

13. RESPIRATORY SYSTEM:- Gaseous exchange occurs through body

surface. Respiratory organ is absent.

 

14. CIRCULATORY SYSTEM: Blood is absent, circulation occurs with the

help of parenchymal fluid.

 

15. EXCRETORY SYSTEM:- Flame Cells, occur for extraction of excretory

products and excess water.

 

16. SENSORY SYSTEM:- It consists of eye spot for photosensitivity, ciliated pits for chemoreception. The sensory structures are present in only free living forms.

 

17. NERVOUS SYSTEM:- It consists of cerebral ganglia, longitudinal nerve cords and transverse commissures Nervous System is ladder like.

 

18. ASEXUAL REPRODUCTION:- It is present in mostly free living forms.

Regeneration is well developed in Dugesia (Planeria).

 

19. SEXUAL REPRODUCTION:- Mostly monoecious. Fertilisation is

commonly internal.

 

20. DEVELOPMENT:- Development may be direct or indirect. Some larvae of platyhelminthes are miracidium, sporocyst, redia, cercaria and

matacercaria.

 

 

 

MEMBERS OF PLATYHELMINTHES

DUGESIA-PLANARIA.Dugesia is free living living leaf like flatworm found in fresh water ponds and slow moving streams. The animal is nocturnal, solitary or gregarious.FASCIOLA HEPATICA-The Liver fluke.

The liver fluke is an endoparasite having two hosts, sheep and fresh water snail. Such a parasite is called digenetic. Sheep or goat is primary host while snail is secondary host. In sheep it resides inside liver and bile ducts.Liver fluke causes liver rot, cirrhosis or fascioliasis disease.TAENIA SOLIUM-The pork Tapeworm.It is a digenetic ghost. Man is primary host where tapeworm lives in intestine. The secondary host is pig.The disorder caused by infection of tapeworm the taeniasis.

 

PART-A:- VERY SHORT ANSWER TYPE QUESTIONS:

A) MULTIPLE CHOICE QUESTIONS:

 

1. Fasciola hepatica occurs in sheep, inside:

(a) Bile ducts

(b) Blood

(c) Spleen

(d) Intestine.

 

2. Liver rot of sheep is caused by:

(a) Fasciola hepatica

(b) Planaria

(c)  Bipallium

(4) | Tapeworm.

 

3. Members of platyhelminthes are also called:

(a) Segmented worms

(b) Flat worms

(c) Round worms

(d) Walking worms

 

4. Taenia solium belongs to phylum:

(a) Mollusca

(b) Platyhelminthes

(c) Annelida

(d) Ctenophora

 

5. Nervous system is ladder like in:

(a) Annelida

(b) Porifera

(c) Platyhelminthes

(d) Ctenophora.

 

B) FILLIN THE BLANKS:-

1. Cysticercosis is a disease caused by

2. is the secondary host of liver fluke.

 

C) TRUE OR FALSE:-

1. Dugesia occurs in fresh water.

2. Flame Cells occur for extraction of excretory products.

 

ANSWER KEY: - PART-A

A) MCQs:-

 

1. a (Sheep is primary host where it lives inside liver and bile duct).

2. a (Flattened nature)

3. b (Due to their flattened body, they are called flat worms)

4. b (Platyhelminthes)

5. c (Nervous system in platyhelminthes is polarised & ladder like,

consisting of cerebral ganglia, longitudinal nerve cord and transverse

commissures.

 

B) FILL IN THE BLANKS:-

1. Taenia

2. Snail

 

C) TRUE OR FALSE:-

1. True

2. True

 

PART-B SHORT ANSWER TYPE QUESTIONS:

1. Prepare a list of platyhelminthes that are found parasitic in human beings?

2. What is digenetic parasite? Give an example?

 

PART-C LONG ANSWER TYPE QUESTIONS:

1. Write any 10 characteristics of phylum Platynelminthes.

A34

 

INTRODUCTION:-It is a phylum of un - segmented, triploblastic, pseudo coelomic, cylindrical or thread like worms which are covered by a body wall having cuticle and epidermis.

 

CHARACTERISTICS OF PHYLUM ASCHELMINTHES:

1. | HABITAT:- Most of the animals are parasitic. A few are free living. Free living forms are found in terrestrial, marine and fresh water habitats.

2. BODY FORM:- The body is commonly cylindrical and elongated, tapering at both the ends. In a cross section, the body appears rounded or circular.So these animals are called round worms.

3. SYMMETRY:- They have eyar system organzaion and Sistera SVP Sty

4. GERM LAYERS:- These are triploblastic animals.

5. These are pseudo-coelomates.

6. Segmentation absent.

7. These are first animals to have straight and complete alimentary canal.These have tube-within a tube plan.

8. RESPIRATORY SYSTEM:- It is JJ Respiration occurs through the

body surface. Free living forms are aerobic while parasitic forms are

anaerobic.

 

9. CIRCULATORY SYSTEM:. The blood vascular system is [Rg

Transportation of materials may take place with the help of hydrolymph or pseudocoelomic fluid.

 

10. EXCRETORY_SYSTEM:- It occurs with the help of either excretory

glands, intracellular canals. These are mostly ammonotelic.

 

11. NERVOUS SYSTEM:- It is formed of a circumpharyngeal nerve ring,

ganglia, connectives, nerve cords and nerves. It is ladder type.

 

12. Sexes are unisexual or dioecious and always show sexual dimorphism.Male is smaller in size, has penial spicules and cloacal aperture (anus in female) Fertilisation is internal.

 

13. EUTELY:- It is a characteristic of round worms. The number of cells and nuclei of cells do not change after maturity. They remain constant.

 

14. SKELETON:- Absent, Hydrolymph function as hydrostatic skeleton.

EXAMPLES:- Ascaris, Rhabditis, Ancylostoma (Hookworm), Enterobius

(pin worm), Wucherena (Filarial worm).

 

ASCARIS LUMBRICOIDES-The Common Round worm.Ascaris has elongated cylindrical body of pinkish to whitish colour with pointed ends. It is endoparasite in the small intestine of human beings. It is monogenetic i.e. without any secondary host. Its infection cause indigestion, colic pain, insomnia, vomiting, diarrnea and retarded body

functions. It is commonly found in children.ANCYCLOSTOMA DUEDENALE-The Hook worm.It is an endoparasite of human small intestine. The parasite is monogenetic. It is popularly called old world hookworm. The male is 8-11mm while femal 10-13mm long. Ancylostoma infection causes abdominal pain,anaemia, diarrhea etc.WUCHERERIA BANCROFTI-The Filaria Worm.It is a digenetic parasite. Human beings are primary host while female Mosquito of Culex species is secondary host. In human body parasite resides in lymph vessels and lymph glands.it causes I disease.

LET US KNOW WHAT WE HAVE LEARNT! |

PART- A: VERY SHORT ANSWER QUESTIONS:-

a) MULTIPLE CHOICE QUESTIONS:-

 

1. Intermediate host of Ascaris lumbricoides is

(a) Pig

(b) Snail

(c) Mosquito

(d) None of above.

 

2. Elephantiasis occurs during infection of Filaria due to:-

(a) Blockage of lymph vessels

(b) Lhmphoderma

(c) Growth and hardening

(d) All of above.

 

3. Ascaris is most commonly found in

(a) Men

(b) Women

(c) Children

(d)Botha&b

 

b) FILL IN THE BLANKS:-

1) In round worms fertilization is

2) Secondary host of Wuchereria is

 

 

c) TRUE OR FALSE--

1) Excretory cells of round worms are H-shaped.

2) Round worms are triploblastic and eucoelomate.

 

ANSWER KEY: PART-A

a) Multiple choice Questions:-

 

1. (d) Ascaris is Monogenetic. (No intermediate host)

2. (d) Wuchereria infection blocks lymph vessels and cause

lymphoderma.

3. (c) Children are more prone to Ascaris infection.

 

b) Fill in the blanks:-

1. Internal

2. Female Mosquito (Culex)

 

C) True or False:-

1. True (Excretory system is H-shaped)

2. False (Round worms are pseudocoelomates)

 

B) SHORT ANSWER TYPE QUESTIONS:

1. Give any three examples of round worm.

2. Enlist Endoparasites which are found inside host body.

3. Mention the special structures possessed by parasites which enable them to survive.

A35

 

INTRODUCTION:Phylum Annelida is a very broad Phylum belonging to the kingdom Animalia.The Annelids are found in marine, terrestrial (damp soil) and freshwater habitats. The name of the phylum is derived from the Latin word annelius, which means a small ring. These are bilaterally symmetrical invertebrates organisms.Approximately 16,500 species have been described in phylum Annelida.Annelids show protostomic development in embryonic stages and are often called "segmented worms" due to their key characteristic of metamerism or true

segmentation.

 

GENERAL CHARACTERISTICS:

1. SYMMETRY: The symmetry is bilateral in annelids.

2. GERM LAYER: the segmented worms are triploblastic.

3. LEVEL OF ORGANISATION: the segmented worms have organ-system

level of organisation.

4. BODY FORM:Elongated wormlike body (<1mm to 3 meters)Hollow tube-within-a-tube design One of the most successful animal designs

: room for development of complex organs with muscle layers

allows for circulation of body fluids _ provides hydrostatic skeleton

Body with well-developed metamerism(= segmentation) Segments are

separated by tissue = septae Each segment has its own set of muscles and other organ Allows more efficient hydrostatic skeleton for burrowing and movement.Each organ is repeated in each segment allows organs of each segment - to become more specialized for various functions such as digestion,respiration, reproduction, locomotion etc.

 

5. HEAD AND PYGIDIUM:

Head (Prostomium & Peristomium)Most annelids show some degree of cephalization with a distinct head (=Prostomium)

Eyes, tentacles, palps, antennae.Peristomium behind prostomium contains the mouth with pharynx and chitinous jaws The pygidium is the posterior or back, end of the worm and houses the ~ anus.

 

6. LOCOMOTION:PARAPODIA: Simple, unjointed lateral extensions supported by chitin. (A Fibrous substance consisting of polysaccharides)

SETAE (Chaetae): Bristles secreted from distal ends of the parapodia.

 

7. BODY WALL: The epidermis a single layer of cells (columnar epithelium)Epidermis secretes a thin flexible protective cuticle

Most annelids have setae a small chitinous bristles secreted by epidermis repeated on each segment (i.e. “bristle worms”) (used as anchors while burrowing, to prevent capture, some used for swimming, or as protection or camouflage Beneath epidermis is two layers of muscle tissue thin layer of circular muscle thick layer of longitudinal muscle (obliquely striated)

 

8. BODY CAVITY: Body Cavity is a true schizocoelous Coelom usually divided into a large number of compartments by intersegmental septa.

 

9. FEEDING & DIGESTION:Complete digestive tract “tube within a tube” design muscle layers allow modification of tract into various structures:~ muscular pharynx- to take in food, often with eversible pharynx with jaws crop — food storage gizzard — food grinding

intestine — digestion and absorption of nutrients _ anus — elimination of undigested wastes

 

10. RESPIRATION:Through body wall in most species Body wall is richly supplied with capillaries to absorb and transport oxygen Some marine forms respire through Parapodia a few species have gills

 

11. CIRCULATION:

Body cavity is filled with coelomic fluid which helps move food and wastes  around.Closed circulatory system that more efficiently carries nutrients and wastes.Several pairs of “pumping hearts” keep blood flowing dorsal and ventral vessels connected by capillary network.dorsal vessel sends blood anteriorly ventral vessel sends blood posteriorly Dorsal vessel is main pump Several pairs of aortic arches (="hearts”) help to keep pressure up in ventral vessel

Blood:Most with dissolved blood pigments to carry oxygen:-  * emoglobin (Fe) red - most annelids hemerythrin (Fe) red .. chlorocruorin (Fe) green (only 4 blood pigments known in animal kingdom & annelid have 3 of them) Blood also contains amoeboid cells which engulf foreign particles (like our WBC's) Annelids therefore have a double transport system for foods, gasses, wastes fluid filled coelom circulatory system with heart & vessels Foods, wastes and respiratory gasses are carried both in blood and in . coelomic fluid

 

12. NERVOUS SYSTEM:

FOO Have both CNS (Central Nervous system) and PNS (Peripheral Nervous System) CNS: Dorsal brain and double nerve cord with paired ganglia in each segment PNS: nerves branch off fused ganglia to supply body wall and body ~ organs.SENSES: Simple single celled photoreceptors or clusters of cells ocelli (= eyespots)

A few polychaete eyes have cornea, lens, retina _ can form images

Statocysts in some for balance Nuchal organ — ciliated pit in head area (may function in chemoreception) Tentacles & palps — well developed sense of touch ENDOCRINE SYSTEM Neurosecretory cells in brain and ganglia secrete hormones that regulate:~ reproduction secondary sex characteristics _ Regeneration

 

13. EXCRETION:

one pair of nephridia (=metanephridia) in each segment

NEPHRIC TUBULE:Nephrostome = funnel like opening into previous segment

Coiled ciliated tubule surrounded by capillaries.Bladder like structure

Nephridipore = opening to outside Function:wastes from coelom are drawn in.salts and organic wastes from blood are discharged into duc.t

useful stuff is selectively reabsorbed.some nitrogen wastes are also excreted through body wall._ excretory organs also help in salt and water balance.

 

14. REPRODUCTION AND DEVELOPMENT:Annelids have both asexual and sexual reproduction quite variable within ~ the phylum.Asexual Budding

Fission

Sexual Monoecious or dioecious most annelids are hermaphrodites.Larva, if present = trochophore (larval stage is characteristic in case of ' indirect development while in others this stage is passed during the development.)

Epitoky is a process that occurs in many species of Polychaete marine “worms wherein a sexually immature worm (Atoke) is modified or transformed into a sexually mature worm (Epitoke). Epitoke are capable of sexual reproduction.The Clitellum is a structure that is present on the anterior portion of the

~ worm that helps to generate the mucus to aid in sperm transfer from one worm to another. It also forms a cocoon within which fertilization occurs.

 

UNIQUE FEATURES OF ANNELIDA:

Metameric Segmentation

Haemoglobin In The Plasma

Nephridia For Excreation And Osmoregulation

Setae

 

ADVANCEMENT OVER NEMATODA (ROUNDWORMS)

Metameric Segmentation Circular and longitudinal muscles are present in both body wall and the wall of alimentary canal.True coelom Blood vascular system contains red blood.

 

ECONOMIC IMPORTANCE OF ANNELIDS:Following are the economic importance of annelids:' Surface and burrowing annelids support production of soil by mixing minerals and organic matter.' Some leeches are still used for bloodletting and also used as fish and wildlife food.' Some annelids prey on other invertebrates ' Nereis are used as food item for foraging birds in the intertidal zone.' Annelids are used as bait for fishing in many parts of world.Earthworm are called friends of farmer because-

Earthworms make burrows and hence aerate the soil, improve drainage

and make the downward growth of roots easier The faeces of earthworm contain nitrate, phosphorus, potassium, and magnesium, which are important component for plant growth.After death earthworms get decomposed in soil and add humus in it.Earthworms also reduce the acidity and alkalinity of the soil.Earthworms play an important role in the decomposition of organic materials in vermicomposting.Earthworms are detritus feeders which feed on decomposing plants and animal parts as well as faeces and play a vital role in the process of decomposition of organic matter and soil metabolism.Generally Eisenia foetidaand Lumbricus rubellisare commonly used to produce vermicompost.The mucus of Earthworm helps in the mineralization and humification of organics in vermicomposting.

 

LET US KNOW WHAT WE HAVE LEARNT!

PART A: VERY SHORT ANSWER TYPE QUESTIONS

A. MULTIPLE CHOICE QUESTIONS

 

1. Segmented body is presented in:

a) Annelida

b) Porifera

c) Mollusca

d) D. Coelenterate

 

2. The excretory organ of annelids is:

a) Flame Cells

b) Nephrostomes

c) Nephridia

d) None of these

 

3. In Annelids Gas Exchange occurs across through:

a) Body wall

b) Appendages

c) Gills

d) All of these

 

4. In Annelida, free swimming larva is called:

a) Madreporite

b) Bipinnaria

c) Brachiolaria

d) Trochophore

 

5. In which of the following, Clitellum is absent.

a) Polychaeta

b) Oligochaeta

c) Hirudinea

d) All of the above.

 

B. TRUE/FALSE

1. In Annelida, Segments are separated by Septa.

2. In Annelids, Parapodia is not a lateral outgrowth of body wall.

3. Chaetal Structure is closely related to lifestyle and locomotion in Annelids.

 

C. FILL IN THE BLANKS

1. The segmentation in Annelida is known as

2. Many Annelids have extemal bristles or

 

ANSWER KEY: PART-A

A. MULTIPLE CHOICE QUESTIONS:

 

Ans 1. A (Annelida)

Ans 2. C (Nephridia)

Ans 3. D (All of these)

Ans 4. D (Trochophore)

Ans 5. A (Polychaeta)

 

 

 

B. TRUE FALSE

Ans 1. True: This type of segmentation is called METAMERISM.

Ans 2. False:Parapodia are paired, unjointed,locomotory lateral appendages.

Ans 3. True: Chaetae are stiff bristles made up of CHITIN.

 

C. FILL IN THE BLANKS

 

Ans 1. Metamerism the body is divided into segments both internally as well as externally.

Ans 2. Setae

 

PART B SHORT ANSWER TYPE QUESTION

Q1. Write note on Parapodia and Setae?

Q2. What is Clitellum?

Q3. What is Trochophore Larva?

 

PART C LONG ANSWER TYPE QUESTIONS

Q1. Describe the general features of Phylum Annelida?

Q2. Write the Economic importance of Phylum Annelida?

A36

 

INTRODUCTION:Arthropods are the animals that are members of the phylum Arthropoda which includes such familiar forms as lobsters, crabs, spiders, mites, insects, centipedes and millipedes. More than 80% of all of the animals in the world are arthropods. More widely distributed over the earth than any other animal phylum, live in virtually every habitat on earth (terrestrial, fresnwater and marine habitats).In fact, their name comes from the Greek ARTHOS (=Jointed) and PODA (=foot). So

Arthropods are the animals with jointed legs.

With such a large group of animals, there is quite a lot of diversity - and quite a lot of

examples - but they do have some similar traits:

Invertebrates.An exoskeleton, or external, skeleton made of chitin and it is covered with a thick protective layer, or cuticle.Segmented bodies.Six legs or more which are jointed.

 

GENERAL CHARACTERISTICS:

1. SYMMETRY: The symmetry is bilateral in arthropods.

2. GERM LAYERS: The arthropods develop from three germ layers. Hence, they are triploblastic.

3. LEVEL OF ORGANISATION: The arthropods have organ-system level of

organisation.

4. BODY FORM:Segmented body Allows infinite possibilities for adaptive modifications.The segments are grouped into two or three regions called tagmata ~ (singular, tagma).Head and Trunk Cephalothorax (The head and Thorax are joined together) and abdomen.Head-Thorax-abdomen

 HEAD:well-developed head (cephalization) with numerous sense organs antennae & compound eyes are characteristic sense organs of arthropods brain (ganglia)

 THORAX: Section with jointed limbs for movement.

ABDOMEN: Contains vital organs; (heart, reproductive organs, digestive organs) Paired jointed appendages Arthropods are the only invertebrates with jointed appendages._ Appendages are also highly adaptable to suit almost infinite functions:sensory —antennae, palps Feeding — mandibles, chelicerae, etc.Locomotion — walking, climbing, swimming, flying, walking,swimming,reproduction defence

 

5. BODY WALL:An outer skeleton made of chitin found in arthropods. Protects internal muscles,blood vessels, etc.It may be thick, heavy and inflexible — Lobsters/crabs or thin, light, and flexible —

Grasshopper , joints/wings._

 Exoskeleton is secreted by epidermis (hypodermis)STRUCTURE:Two major layers each further subdivided into finer layers:' Quter thin epicuticle: hardened (= sclerotized) protein,with waxy surface for waterproofing._ Inner much thicker, procuticle (includes exocuticle and endocuticle)thick outer layer of chitin above a_ thinner inner layer that remains thin and flexible.

. exoskeleton is often highly coloured:

- camouflage

recognition

_ warning various microscopic canals run through cuticle and

- open to outside:pore canals —calcium salts for sclerotization in crustacea wax canals — secrete waxy covering for water proofing

_ dermal gland ducts — unknown function with the advantages of this exoskeleton it has one major drawback:Animals can't grow without shedding and re-growing a larger exoskeleton.The problem is solved by molting.Molting — The process of shedding, or losing, the rigid exoskeleton to let the organism grow. In arthropods this is Known as Ecdysis. (Includes actual shedding of old cuticle).

 

6. BODY CAVITY: Arthropods also have a haemocoel, an open body cavity in which blood flows and bathes the tissues and organs.

 

7. MOVEMENT:virtually every form of animal movement is found in arthropods like ; walking, running, crawling, burrowing, swimming, flying, etc.arthropods have a very complex muscular system the jointed plates of the body and legs provide attachment point for muscles.

 

8. FEEDING & DIGESTION:Have a one-way digestive system (runs from mouth to anus).Developed system: Contains aforegut(pharynx and esophagus to the stomach), midgut (stomach), and hindgut (colon, anus) — much like humans.mouth: salivary glands esophagus: tube that brings food to stomach stomach: often with specialized areas for grinding and storing and absorbing food eg. crop, gizzard and accessory glands that secrete enzymes and digestive juices intestine: efficient areas for absorption of nutrients . anus: discards unused materials

 

9.RESPIRATION:Aquatic arthropods possess gills for respiration.They vary in structure and location but are all outgrowths of integument (skin) and are therefore covered by the exoskeleton (which is thin enough that gas exchange can occur).Terrestrial Arthropods use book lungs and trachea as respiratory organs.Trachea — Tiny tubes that run around the body to transport gases. (insects)Spiracle — Opening to the Tracheae from the outside.Ren. Gases still enter/exit through spiracles, but gas is exchanged in the blood in the “pages” of the lung area, rather than filling a system of trachea (as in insects).

 

10. CIRCULATION:_ Arthropods have a simple open circulatory system.

coelom becomes hemocoel filled with blood as in most molluscs.has dorsal heart and only a few blood vessels.dorsal blood vessel with paired ostia in each segment.blood flows anteriorly in dorsal vessel out into segments and circulates around organs and back to dorsal vessel.no capillaries blood of most arthropods contains pigments to carry oxygen:

eg. Hemocyanin — bluish pigment with Copper

eg. A — EE pigment containing Iron

 

11. NERVOUS SYSTEM:- Similar to annelids: dorsal brain and double nerve cord with paired ganglia in - each segment.

SENSE ORGANS: Eyes

Simple Eyes = ocelli . can detect only light vs dark Compound Eyes

with many individual lenses = facets Provide a wide field of view and particularly good at detecting movement.Antennae tactile & chemical sensations.Chemoreceptors In addition to being on antennae, can be found on almost any body surface. e.g, many insects have chemoreceptors on their feet.Tactile Hairs & spines equivalent to our sense of touch

Statocysts for balance

 

12. EXCRETION:Arthropods have a variety of efficient excretory systems to:remove excretory wastes also prevents excessive water loss on land

Antennal glands excretory organs at the base of antennae in crustaceans used to regulate salt balance.Malpighian tubules are excretory organs unique to Arachnids and Hexapods branch from hindgut or rectum.

collects salts and wastes and drains into the intestine.Coxal glands modified nephridia at base of legs in some Chelicerates.In some aquatic species nitrogen wastes are excreted through skin or through gills.

 

13. REPRODUCTION AND DEVELOPMENT: Typically Sexual Reproduction

Internal fertilization (on land):- Sperm is transferred into the female via packets called spermatophores.External fertilization (in water).

Separate sexes in arthropods.Paired sex organs, or gonads, are connected directly to ducts that open onto the ventral surface (front/belly) .lots of variation in developmental stages:

eg. larva metamorphosis adult larvae  caterpillars, grubs, maggots, nauplius in crustacea.eg. nymph juvenile adult Some insects (like Stick Insects) can asexually reproduce through parthenogenesis (when an adult forms from an unfertilized egg (asexual reproduction).In social insects (honeybees & ants).Unfertilized eggs (haploid) develop into the male drones. Fertilized eggs (diploid) develop into the female workers and queens.

CLASSIFICATION OF ARTHROPODA There are six classes of arthropods namely Crustacea, Chilopoda, Diplopoda, Insecta, Arachnida and Merostomata.

 

IMPACT OF ARTHROPODS AND PESTS

Beneficial Arthropods

The majority of them are beneficial.

Some pollinate crops.

Some produce useful products: Honey and Silk.

Some kill or control pests.

Problematic Arthropods

Destroy Field crops.

Destroy wooden structures.

Destroy stored food products.

Spread disease and cause direct effect on health.

 

LET US KNOW WHAT WE HAVE LEARNT!

PART A: VERY SHORT ANSWER TYPE QUESTIONS:

A. MULTIPLE CHOICE QUESTIONS:

 

1. In arthropods, there is complete:

a) Circulatory system

b) Respiratory structures

c) Digestive system

d) Reproductive structures

 

2. The growth in arthropods goes along with this process:

a) Mitosis

b) only molting

c) only ecdysis

d) ecdysis and molting

 

3. Arthropod exoskeleton is:

a) Softened

b) Flexible

c) Hardened and inflexible

d) Softened and flexible

 

4. Crustacea have cuticle hardened by:

a) Potassium salts

b) Collage

c) Calcium salts

d) Magnesium salts

 

5. Book Lungs are the respiratory organs of:

a) Insects

b) Crustaceans

c) Arachnids

d) Peripatus

 

 

 

B. TRUE/FALSE:

6. Chitin is a tough leathery protein.

7. The periodic shedding of exoskeleton for growth in arthropods is called molting process called segmentation.

8. Jointed appendages are found in arthropods.

 

C. FILL IN THE BLANKS

9. In arthropod the need to moult during growth provide an opportunity for

10. Some arthropods have a fused head and thorax called a

 

ANSWER KEY: PART-A

A. MULTIPLE CHOICE QUESTIONS:

 

Ans 1. c) Digestive system

Ans 2. d) Ecdysis and molting

Ans 3. c) Hardened and inflexible

Ans 4. c) Calcium salts

Ans 5. c) Arachnids

 

B. TRUE FALSE:

Ans 6. False (polysacchrides)

Ans 7. False (Ecdysis)

Ans 8. True

 

C. FILL IN THE BLANKS:

Ans 9. Metamorphosis

Ans 10. Cephalothorax

 

 

PART-B SHORT ANSWER TYPE QUESTIONS:

Q1. Chart the classifications of Phylum Arthropoda?

Q2. Give the examples of Class Arachnida?

Q3. What is Metamorphosis and why has it contributed to Arthropod success?

Q4. What is Molting and dangers of molting?

Q5. What type of blood vascular system is present in the Arthropods?

 

PART-C LONG ANSWER TYPE QUESTIONS:

Q1. Describe the general features of Phylum Arthropoda?

Q2. What are the reasons that you can think of, for the Athropods to constitute the largest group of the animal kingdom?

A37

 

INTRODUCTION:PHYLUM MOLLUSCA- The soft bodied animals (L. Molluscs- soft)Phylum Mollusca includes soft bodied, unsegmented, eucoelomate animals. These are called molluscs or shelled animals. Johnston (1650) coined the term ‘Mollusca’.It is the second largest animal phylum and includes about 85000 species.

 

GENERAL CHARACTERISTICS OF MOLLUSCA:

 

1 Habitat: They are mostly marine. Many, however, occur in fresh water and some even in damp soil.

2 Body form: The body of molluscs is unsegmented with a distinct head,

muscular foot and visceral hump. Neopilina is a segmented mollusc.

3 Symmetry: They usually show bilateral symmetry. In some molluscs like

Pila, due to twisting during growth, the adults become asymmetrical.

4 Shell: Shell is secreted by mantle. It is made up of calcium carbonate. Shell may be external (e.g. most of molluscs), internal (e.g. slug, cuttle fish) or absent (e.g. Octopus).

5 Mantle (Pallium): It is a thin, fleshy fold of dorsal body wall more or less covering the body. It encloses a space, which is called mantle cavity.

6 Body Wall: Body wall is single layered epidermis is usually ciliated. Muscles are unstriped and occur in bundles.

7 Body cavity: The coelom is greatly reduced although they are eucoelomate.

8 Digestive tract: It is complete.

9 Blood vascular system: It is open type. It includes dorsal heart, arteries that open into sinuses and veins. Blood is blue due to the presence of haemocyanin.

 

10 Respiratory organs: These are gills (ctenidia), mantle and pulmonary sac (in semi terrestrial forms).

 

11 Excretory organs: These are one or two pairs of sac- like kidneys. Gills are also excretory in function. Ammonia is the chief excretory material.

 

12 Skelton: Molluscs generally have shell as exoskeleton.

 

13 Sense organs: These have eyes, statocyst, and tentacles for equilibrium and receptors for touch, smell and taste.

 

14. Nervous System: Few pairs of ganglia like cerebral visceral and pedal with nerves are present.

 

15. Reproduction: Molluscs reproduce sexually. Sexes are separate and

mostly oviparous. Fertilisation is external or internal.

 

16. Development: They are oviparous. The development is either direct or indirect (metamorphosis). When the development is indirect it includes a characteristic larva. Asexual reproduction is absent.

 

UNIQUE FEATURES OF MOLLUSCANS:

(i) Mantle covers the body,

(ii)Mantle may be surrounded by shell, and

(ii) Nervous system consists of cerebral, visceral, pleural and pedal

ganglia.

 

ADVANCEMENT OVER ANNELIDS:

(i) Shellis present in many individuals,

(ii)In some forms, a lungs is present for pulmonary respiration, and

(iii) Better developed sense organs such as eyes, statocysts and

osphradia.

 

CLASSIFICATION OF PHYLUM MOLLUSCA:

Phylum Mollusca are divided into six classes.

Class 1. Monoplacophora (Gk. monas- one, plax- plate, pherein-bearing): The shell is spoon or cup shaped. They have die characters of both the phylum Annelida and phylum Mollusca, e.g. Neopilina.

Class 2. Amphineura (Gk. amphi both + two neuron = nerve): There is a

present non-ganglionated nerve ring around mouth with two pairs of

interconnected nerve cord, e.g. Chaetopleura (Chiton).

Class 3. Scaphopoda (Gk. scapha- boat, podos- foot): Shell is tubular and open at both ends, e.g. Dentalium.

 

Class 4. Gastropoda (Gk. gaster- belly, podos- foot): Shell is made up of one piece. The early embryo is symmetrical but during development the body twists showing torsion so that the body becomes asymmetrical. It includes the largest number of molluscs e.g. Pila.

Class 5. Pelecypoda (Gk. pelekus- hatchet Podos foot): Shells is made up of two halves, e.g. Unio.

Class 6. Cephalopoda (Gk. kephale- head, podos- foot): Head and foot

region combined and modified into a structure which has eyes and eight

tentacles, hence the name cephalopod or ‘head foot’ , e.g. Sepia, Octopus.Examples: Pila (apple snail), Sepia (cuttle fish), Octopus (devil fish).

 

LET US KNOW WHAT WE HAVELEARNT!

PART: A VERY SHORT ANSWER QUESTIONS:-

a) MULTIPLE CHOICE QUESTIONS :-

 

1) In molluscs, shell is secreted by:

a) mantle

b) foot

c)head

d) visceral hump

 

2) Pallium encloses a space which is called:

a) muscular foot

b) coelom

c) mantle cavity

d) digestive tract

 

 

 

3) Which of the following is not a mollusc?

a) Pila

b) Sepia

c) Octopus

d) Star fish

 

4) Phylum mollusc is divided into:

a) six classes

b) two classes

c) four classes

d) five classes

 

b) TRUE OR FALSE.-

1) Moliuscs are soft bodied animals.

2) Molluscua is the largest animal phylum.

 

c) FILL IN THE BLANKS:-

1) is secreted by mantle.

2) Blood is blue due to the presence of .

3) is chief excretory material in moluuscs.

 

PART:B SHORT ANSWER TYPEQUESTIONS:-

1) What are molluscs? Name any two.

2) Define Pallium. Name various respiratory organs in molluscs.

3) Write unique Features of phylum Mollusca.

 

 

ANSWER KEY PART A&B

PART- A: VERY SHORT ANSWER TYPE QUESTIONS:

a) MULTIPLE CHOICE QUESTIONS:-

 

1. a) mantle

2. c) mantle cavity

3. d) Star fish

4. a) six classes

 

b) TRUE OR FALSE:-

1. True

2. False

 

c) FILL IN THE BLANKS:-

1. Shell

2. Haemocyanin

3. Ammonia

 

PART-B SHORT ANSWER TYPE QUESTIONS:-

1) Animals belonging to phylum Mollusca are commonly known as

Molluscs e.g. Pila (apple snail), Sepia (cuttle fish), Octopus (devil fish).

 

2) Mantle (Pallium) it is a thin, fleshy fold of dorsal body wall more or less covering the body. It encloses a space, which is called mantle

cavity. Various respiratory organs in molluscs are gills (ctenidia),

mantle and pulmonary sac (in semi terrestrial forms).

 

3) Unique Features of phylum Mollusca are Mantle covers the body,

Mantle may be surrounded by shell, and Nervous system consists of

cerebral, visceral, pleural and pedal ganglia.

 

A38

 

INTRODUCTION:PHYLUM Echinodermata -(Gk. Echinos- spines; derma- skin / covering)Phylum ECHINODERMATA consists of only marine animals. It includes about 6,000 species. Jacob Klein (1738) introduced the name “Echinodermata”.Endoskeleton of calcareous ossicles is present.

GENERAL CHARACTERISTICS OF ECHINODERMS:

1. Habitat: All existing echinoderms are marine. They generally live at sea bottom.

2. Body form: It varies considerably. The body is star-shaped, spherical or cylindrical. It is unsegmented. The body lacks head.

3. Symmetry: They usually show bilateral symmetry in larvae but pentamerous radial in adults.

4. Spines and Pedicellariae: Many echinoderms bear spines and pincer-like pedicellariae. The spines are protective in function. The pedicellariae keep the body surface clear of debris and minute organisms.

5. Water Vascular system: They have a unique water vascular system. It is in the form of radiating canals which form several intricate systems performing different functions. The water vascular system pushes out the body surface as series of tube feet which can be protruded by altering the fluid pressure. It helps in locomotion, capture and transport of food and respiration.

6. Body Wall: Body wall is single layered and ciliated.

7. Body cavity: There is a true enterocoelic coelom.

8. Digestive tract: It is usually complete. Brittle stars have incomplete.

9. Haemal and Perihaemal system: Instead of blood vascular system, there are present of haemai and perihaemal systems which are of coelomic origin. Thus so called circulatory system in open type and includes haemal and perihaemal systems. Blood is without any respiratory pigment. There is no heart.

 

10 Respiratory organs: Gaseous exchange occurs by dermal branchae or

papulae in star fish, peristominal gills in sea urchins, genital bursae in brittle stars and cloacal rerspiratory trees in holothurians. Exchange of gases also takes place through tube feet.

10Excretory organs: Specialized excretory organs are absent. Nitrogenous wastes are diffused out via gills. Ammonia is chief excretory material.

11 Sense organs: They are poorly developed.

12 Nervous System: It consists of a nerve ring and radial nerve cords. Brain as such is absent.

13 Asexual Reproduction: Some forms reproduce asexually by self-division.

14 Sexual Reproduction: Sexes are separate. No sexual

dimorphism.Fertilization external.Oviparous or ovoviviparous.

 

UNIQUE FEATURES:

(i) Presence of spines and pedicellariae.

(ii) Water canal system and haemal system.

(iii) Bilateral symmetry in the larva and radial symmetry in the adult.

 

CLASSIFICATION OF PHYLUM ECHINODERMATA:

Phylum echinodermata are divided into five classes.

 

Class 1. Asteroidea : Body is star-like. Five arms are usually present, e.g.Star fish.

Class 2. Ophiuroidea: Body is star-like; arms are sharply marked off from the central disc, e.g. brittle star.

Class 3. Echinoidea: Body is globular or disc like, e.g. Sea urchin.

Class 4. Holothuroidea: Body is elongated and cylindrical. Oral end has

mouth surrounded by tentacles, e.g. Sea cucumber.

Class 5. Crinoidea: Body has a central disc which is attached to the

substratum. Arms are branched e.g. Antedon.

 

LET US KNOW WHAT WE LEARN?

PART:A VERY SHORT ANSWER TYPE QUESTIONS:-

a) Multiple choice Questions:-

 

1) Which of the following group is only marine:

a) coelenterata

b) mollusca

c) echinodermata

d) porifera

 

2) Spines in echinodermates function as:

a) protection

b) locomotion

c) to keep the body surface clean

d) respiration

 

3) What does the term echinodermata means:

a) tube feet

b) Star shaped

c) spiny skinned

d) stomach foot

 

4) Phylum echinodermata is divided into:

a) six classes

b) two classes

c) four classes

d) five classes

 

 

b) True or False:-

1) Echinodermata are the spiny skinned animals.

2) Sense organs are well developed in echinodermates.

 

c) Fill in the blanks:-

1) is a unique system found in echinodermates.

2) Body cavity is a true coelom.

3) is chief excretory material in echinodermates.

 

ANSWER KEY: PART -A

a) Multiple choice Questions:-

1. c) echinodermata

2. a) protection

3. c) spiny skinned

4. c) five classes

 

b) True or False:-

1. True

2. False

 

c) Fill in the blanks:-

1. Water vascular system

2. Enterocoelic

3. Ammonia

PART: B SHORT ANSWER TYPE QUESTIONS:-

1) What are echinodermates? Name any two.

2) What is water vascular system? Name various respiratory organs in

echinodermates.

 

PART: C SHORT ANSWER TYPE QUESTIONS:-

1) Write unique features of phylum Echinodermata.

A39

 

INTRODUCTION:PHYLUM: HEMICHORDATA (Gk. Hemi- half; chordata- notochord)

This phylum was earlier considered as sub- phylum under phylum

Chordata. But afterwards, it is placed under Non-Chordates as a

separate phylum.This phylum consists of worm like marine animals, with organ system level of organization.The body is cylindrical, composed of an anterior proboscis, a collar and a long trunk.

 

CHARACTERISTICS OF HEMICHORDATA

1) They are exclusively marine and benthic.

2) The body is divisible into proboscis, collar, and trunk.

3) These are triploblastic animals.

4) Body is bilaterally symmetrical.

5) Body wall with a single layered epidermis with mucous gland

6) The alimentary canal is a straight, complete or u-shaped tube.

7) Proboscis acts as locomotory and food capturing organ

8) Ciliated pharyngeal gill-slits are present which acts as respiratory organ.

9) Circulatory system is open type.

10) Excretion by a single glomerulus situated in the proboscis.

11) Body segmentation is not seen in these animals.

12) Reproduction is mainly sexual.

13) Fertilization is external in seawater.

14) Development is direct or indirect with free swimming

15) Organ system grade of body organization is seen.

16) Notochord is absent.

17) Sensory cell of the epidermis acts as sense organs.

EXAMPLES: Balanoglossus, Rhabdopleura, Saccoglossus.

 

LET US KNOW WHAT WE HAVE LEARNT!

A) VERY SHORT ANSWER QUESTIONS:-

a) Multiple choice Questions:-

 

1) The larva of the hemichordate is:

(a) Trochophora

(b) Tornaria

(c) Planula

(d) mullers larva

 

2) Locomotion occurs by:

(a) Proboscis

(b) Collar

(c) Trunk

(d)BothA andB

 

 

 

3) Respiratory organ in hemichordate is :

(a) Pharyngeal gill slits

(b) Proboscis

(c) Mucous gland

(d) Collar.

 

4) Type of symmetry in hemichordates:

(a)Radial

(b) Bilateral

(c) Biradial

(d) Spherical

 

5) Type of circulatory system in hemichordates :

(a) Open

(b) Closed

(c) Only B

(d) Both A and B

 

b) True or False:-

1. In hemichordates body is divisible into proboscis, collar, and trunk.

2. Closed circulatory system is present in hemichordates.

3. Proboscis acts as locomotory organ.

 

c) Fill in the blanks:-

1. symmetry is present in hemichordates.

2. is the larval stage in hemichordates.

 

ANSWER KEY : PART-A

a) Multiple choice Questions: -

 

1. (b) Tornariais the larval stage in hemichordates.

2. (a) Proboscis.

3. (a) Pharyngeal gill slits.

4. (b) Bilateral .

5. (a) Open.

 

b) True or False:-

1. True

2. False

3. True

 

c) Fill in the blanks:-

1. Bilateral

2 Tornaria larva.

 

B) SHORT ANSWER TYPE QUESTIONS:-

1) Discuss type of circulatory system in Hemichordata.

2) Write the function of proboscis in Hemichordata.

3) How does respiration occur in Hemichordates?

 

A) LONG ANSWER TYPE QUESTIONS:-

1) Discuss characteristic features of hemichordates.

A40

 

INTRODUCTION:PHYLUM: CHORDATA (Gk. Chordata- notochord)

Animals belonging to phylum CHORDATA are fundamentally

characterized by the presence of a notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits.These are Bilaterally Symmetrical, Triploblastic, Coelomate with Organ Level of

Organization.They possess a post anal tail and a closed circulatory system.

 

CHARACTERISTICS OF PHYLUM CHORDATA:

Phylum Chordata possesses the following characteristic features:

 

1. NOTOCHORD:It is a longitudinal, cartilaginous rod running between the nerve cord and the digestive tract. It acts as a support for the nerve cord and is replaced by the vertebral column after the embryonic stage in all vertebrates.

 

2. DORSAL HOLLOW NERVE CHORD:It is a bundle of nerves running along the “back” and splits into the brain and the spinal cord. It is hollow and lies dorsal to the notochord.

 

3. Paired Pharyngeal Gill Slits:They are the openings which allow the entry of water through the mouth without entering the digestive system viz. they connect mouth and throat. All Chordates have these openings on the lateral sides of the pharynx at some stage of their life.

 

4. Post anal Tail:It is an extension of the body to the anus. In chordates, the tail is composed of skeletal muscles which help in locomotion in fish-like species. It is absent in most of the adult Chordates.

 

 

 

 

OTHER CHARACTERISTICS OF CHORDATES INCLUDE:

1. Bilaterally symmetrical, triploblastic, coelomic.

2. The body design is complex and well-differentiated.

3. The body has an organ system level of organization.

4. Closed circulatory system, ventral heart.

 

CLASSIFICATION OF PHYLUM CHORDATA:

PHYLUM CHORDATA IS CLASSIFIED INTO THREE SUBPHYLA:

1. Urochordata (tunicates),

2. Cephalochordata (lancelets)

3. Vertebrata (vertebrates)

 

The subphylum Urochordata and Cephalochordata are collectively known

as protochordates, which are marine animals. They are invertebrates but they share attributes of chordates.

 

UROCHORDATA:The adults are fixed to the substratum.It is also known as tunicate because the body of an adult is enclosed within a tunic made up of cellulose -like substance known as tunicin.Notochord can be seen only in the larval stage and disappears in the adults.

- The nerve cord present in larva is replaced by a dorsal ganglion in adults.e.g. Ascidia, Salpa, Doliolum.

 

CEPHALOCHORDATA:The atrium is present. The tail is present throughout life.The notochord is found throughout life._ Numerous well-developed pharyngeal gill slits are present.e.g., Lancelets possess the notochord and nerve cord throughout their life. However, they lack the brain and bony vertebral column like Branchiostoma. (Amphioxus)

 

VERTEBRATA:THE CHARACTERISTIC FEATURES OF VERTEBRATES INCLUDE:

These are advanced chordates and have cranium around the brain.The notochord is replaced by a vertebral column in adults.This is why it is said that ‘all vertebrates are chordates but all chordates are

not vertebrates’.The epidermis is multi-layered.They consist of three types of muscles-striped, unstriped and cardiac.They have a well-developed coelom.The alimentary canal is complete.The heart is three

four-chambered.They have well-developed respiratory and excretory

systems.Endocrine glands present in all.They are unisexual reproduce sexually,hagfish being an exception.e.g., humans.

SUBPHYLUM VERTEBRATA IS FURTHER CLASSIFIED INTO SEVEN CLASSES.

They are:

1. Cyclostomata

2. Chondrichthyes

3. Osteichthyes

4. Amphibia

5. Reptilia

6. Aves

7. Mammalia

 

LET US KNOW WHAT WE HAVE LEARNT!

PART:A VERY SHORT ANSWER TYPE QUESTIONS:-

a) Multiple choice Questions:-

 

1. Jawless fishes are placed under the division:

a) Gnathostomata

b) Pisces

c) Tetrapoda

(d) Agnatha

 

2. Which of the following have notochord throughout their life?

b) Amphioxus

b ) Fish

c) Snake

d) Bird

 

3. The characteristic of Urochordata, having a tail and a:

a) Backbone

b) Notochord

c) Spine

d) Buccal cavity

 

4. Sub phylum Urochordata and Cephalochordata are often referred to as:

a) Protochordata

b) Hemichordata

c) Chordata

d) Non-chordata

 

5. Which of the following is not a character of Chordate embryo?

a) Dorsal tubular nerve cord

b) Presence of Notochord

c) Pharyngeal gill slits

d) Presence of spinal cord

 

 

 

 

b) True or False:-

1. Branchiostoma is an example of sub-phylum cephalochordata.

2. Phylum vertabrata has incomplete alimentary canal.

3. Urochordata is also known as tunicates.

 

c) Fillin the Blanks:-

1. The body of chordates have an system level of organization.

2. is a longitudinal, cartilaginous rod running between the nerve

cord and the digestive tract.

 

ANSWER KEY: PART -A

a) Multiple choice Questions:-

 

1.d (Agnatha) : pisces and tetrapoda are with jaws.

2. a (Amphioxus) : in others notochord is replaced by vertebral column.

3.c (Notochord) : notochord is present only in larval tail.

4.a (Protochordata): proto means before . So before chordate.

5.d (Presence of spinal cord)

 

b) True or False:-

1. True : Branchiostoma also known as Amphious or Lancelet.

2. False: Alimentary canal is complete in vertebrates.

3. True: As adult body is enclosed in tunic made of tunicin.

 

C) Fill in the blanks:-

1. Organ

2. Notochord

 

PART: B SHORT ANSWER TYPE QUESTIONS:-

1. List three basic characteristics of Phylum chordata.

2. Give the characteristic features of the following citing one example of each.

a) Urochordata b) Cephalochordata

3. “All vertebrates are chordates but all chordates are not vertebrates. "Justify the

statement.

 

PART: C LONG ANSWER QUESTIONS:-

1. Illustrate the classification of Phylum Chordata with the help of flowchart.

2. How are chordates different from Non- chordates?

A41

 

INTRODUCTION:Class: Cyclostomata (Gk. Cyklos- circular; stome- mouth)

The Cyclostomata are the modified and degenerate offshoot of the primitiv vertebrate stalk. Due to their circular mouth, they are named Cyclostomata.They come under:Phylum-Chordata, Sub-Phylum- Vertebrata, and Section- Agnatha.They are parasitic, usually feeding on fish in their adult stage. Morphologically, the resemble Eels. They are known to be the only living vertebrates without tru jaws, hence called Agnatha.CYCLOSTOMATA includes Hagfishes and Lampreys.Another class under section Agnatha is OSTRACODERMI, that has become extinct.

 

CHARACTERISTICS OF CYCLOSTOMATA

The body is round and elongated like an eel.The paired fins are absent. Median fins with cartilaginous fin rays.

No paired appendages.The skin is soft and smooth, devoid of any scales.Spleen is absent.The exoskeleton is absent.The endoskeleton is cartilaginous with no bones.

The notochord is present throughout their lives.The digestive system is devoid of any stomach.The nostril is single and median.The gills are five to sixteen in pairs.The heart is two-chambered.The brain is visible.The lateral line acts as a sense organ.About ten pairs of cranial nerves are present.The sexes are separate.Some hagfish species are believed to be hermaphrodite.A pair of mesonephric kidneys make up the excretory system.Development may be direct or indirect.e.g. Petromyzon and Maxine.

 

SUB-DIVISIONS OF CLASS CYCLOSTOMATA:

The cyclostomes are sub-divided into two major orders:

 

1) PETROMYZONTIFORME:Lampreys or lamper eels belong to this order.

They are found in both marine and freshwater.They have a ventral mouth with many horny teeth.The nostril is present dorsally.They possess a well-developed dorsal fin.The dorsal and ventral roots of spinal nerves are separate.The development is indirect.e.g. Petromyzon, Lampetra

 

2) MYXINIFORMES:Hagfishes represent this order.They are found exclusively in the marine environment.They have a terminal mouth with few teeth.

They have no buccal cavity.The nostril is terminal.They possess 6-14 pairs of gill slits.The dorsal and ventral roots of the spinal nerves are not separate.Eggs are large and few in number.

The dorsal fin is usually absent, or weak.e.g. Myxine, Paramyxine.

 

LET US KNOW WHAT WE HAVELEARNT!

PART: A VERY SHORT ANSWER TYPE QUESTIONS:-

a) Multiple choice Questions:-

 

1. Cyclostomes have:

(a) 6-15 pairs of gill slits for respiration

(b) Sucking and circular mouth without jaws

(c) Elongated body

(d) All are true

 

 

2. The member of the class myxiniforme are:

(a)Hagfishes

(b)Agnathans

(c) Ostraccoderms

(d) Urochords

 

3. Choose the false statement: Cyclotomes have:

(a) Soft and smooth skin

(b) Paired fins

(c) Nostril is single

(d) Heart is two chambered

 

4. Which type of mode of nutrition is present in class Cyclostomata?

(a)Saprophytic

(b) Parasitic

(c) Autotrophic

(d) Holozoic

 

5. Which of the following are the major orders of class Cyclostomata?

(a) Petromyzontiformes

(b) Myxiniformes

(c) Both a andb

(d) None of these

 

 

 

 

b) True or False:-

1. Cyclostomata have paired appendages.

2. Hagfishes have terminal mouth with few teeth.

3. Cyclostomes have three chambered heart.

 

c) Fill in the blanks:-

1. have a sucking and circular mouth without jaws.

2. belong to order Myxiniformes.

 

ANSWER KEY: PART-A

VERY SHORT ANSWER QUESTIONS:-

a) Multiple choice Questions:-

 

1.d (All are true)

2.a (Hagfishes)

3.b (Paired fins)

4.b (Parasitic)

5.c (Botha and b)

 

b) True or False:-

1. False

2. True

3. False

 

c) Fill in the blanks:-

1. Lamprey

2. Hagfish

 

B) SHORT ANSWER TYPE QUESTIONS:-

1. List the basic characteristics of Class cyclostomata.

2. Give the characteristic features of the following citing one example of each

A) Petromyzontiformes B) Myxiniformes

A42

 

Classes CHONDRICHTHYES & OSTEICHTHYES, belongs to:Phylum; Chordata, Sub- Phylum; Vertebrata, Section; Gnathostomata and Super Class; PISCES.PISCES (FISHES) (L. Pisces- fish)It is a super class of jaw bearing, aquatic vertebrates having paired gills for aquatic

respiration & paired as well as un paired fins for aquatic locomotion. They found in fresh, marine, and brackish water. Laterally compressed, streamlined, spindle-shaped elongated body. They are cold blooded or poikilothermic animals.

 

They can be classified into two Classes:

1. Chondrichthyes 2. Osteichthyes

(Gk. chondron- cartilage and ichthyes- fish)

 

CHARACTERISTICS:They are marine animals; FISHES with streamlined body and have cartilaginous endoskeleton.Exoskeleton is formed of dermal placoid scales.They swim in water with the help of fins.Paired fins are pelvic and pectoral.Unpaired fins are dorsal, ventral and caudal.

They have two dorsal fins.Tail fin is heterocercal.Air bladder is absent. So have to swim continuously to avoid sinking.Mouth is ventral in position.Heart is two- chambered.Respiration takes place through gills.

Lateral line sensory system is present.Cartilage fishes are ureotelic in excretion.Sexes are separate. Males have Claspers between the pelvic fins.Fertilization is internal.They are generally oviparous but some members are viviparous.Some of them have Electric Organs (e.g. Torpedo)Some possess Poison Sting (e.g. Trygon)(Greek word ‘osteon- bone and ichthyes- fish)These are marine and fresh water fishes with bony endoskeleton.Exoskeleton is formed of dermal Cycloid or Ctenoid scales.These swim in water with the help of fins.Paired fins are pelvic and pectoral.Unpaired fins are dorsal, ventral and caudal.These have single dorsal fin.Tail fin is homocercal.Air bladder is present which regulates buoyancy.

Mouth is terminal in postion Heart is two - chambered.Respiration takes place through gills.Bony fishes are ammonotelic in excretion.Sexes are separate. Claspers are never present.Fertilization is external.They are mostly oviparous.

 

[LET US KNOW WHAT WE HAVE LEARNT! ]

a) MULTIPLE CHOICE QUESTIONS:-

 

Q1. Heart of fishes is:

(a) One chambered

(b) Two chambered

(C)Three chambered

(d) Four chambered

 

Q2. Fishes are:

(a) Homeothermic

(b) Poikilothermic

(c) Both (a) and (b)

(d) None of these

 

Q3. Study of fishes is known as:

(a) Serpentology

(b) Herpetology

(c) Ichthyology

(d) None of these

 

 

Q4. Lateral line system is present in:

(a) Fish

(b) Frog

(c) Reptiles

(d) Man

 

Q5.The excretory matter of bony fish is:

(a) Urea

(b) Protein

(c) Ammonia

(d) Amino acid

 

b) FILL IN THE BLANKS:-

1. Fishes with cartilaginous endoskeleton belong to class .

2. Fishes are animals.

 

c) TRUE / FALSE:-

1. Heart is three chambered in fishes.

2. Cartilage fisn has heterocercal tail fin.

3. Bony fishes are ureotelic in excretion.

 

ANSWER KEY: PART -A

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

a)Multiple choice Questions:-

 

1.(B) Two - chambered

2. (B) Poikilothermic

3. (C) Ichthyology

4. (A) Fish

5. (C) Ammonia

 

b) FILL IN THE BLANKS:-

1. Chondrichthyes

2. Cold - blooded (poikilothermic)

 

c) TRUE OR FALSE:-

1. False

2. True

3. False

 

Part B SHORT TYPE QUESTIONS:-

1. What is Ichthyology?

2. Write three common characters of fishes?

3. Which type of tail fin is found in bony fish?

A43

 

INTRODUCTION:The organisms belonging to the class Amphibia fall under the Chordata phylum of the kingdom animalia.The word ‘amphi' means ‘double’ and ‘bios’ means ‘life’.These are Multicellular Vertebrates that live both on land and in water.They are the first cold blooded animals to have appeared on land.- These can live both on land and in water.The Skin is thin , moist , glandular and vascular.Exoskeleton is always absent.Endoskeleton is mainly bony. Skull is Dicondylic ( with 2 occipitalcondyles ).They have two pairs of Pentadactyl limbs for locomotion.The body is divisible into well developed head and trunk.

Alimentary canal, urinary and reproductive tracts open into a common

chamber called Cloaca which opens into a exterior.The respiratory organs are lungs , buccopharyngeal cavity , skin and gills.Heart is three - chambered having two auricles and one ventricle.The eye have eyelids. Nictitating membrane is well developed.Brain has 10 pairs of cranial nerves.Ear is formed of only internal and middle ear. Middle ear has only one ear -ossicle called stapes. Tympanum lies on the surface. Kidneys are mesonephric. Larvae and tailed amphibians (e.g;

salamanders) are ammonotelic. Frogs and toads are ureotelic.These are cold blooded animals , so hibernate in winter and aestivate in summer months.Sexes are separate.They are oviparous and development is indirect and includes an aquatic fishes like larva (e.g; Tadpole in frog and axolotl in salamander).which undergoes metamorphosis.They occur in fresh water and moist land.

CLASS - REPTILIA The word ‘repre’ means to ‘creep’ or ‘crawl’.These were the first class of organisms to adapt to life on earth.They are believed to have evolved from the amphibians millions of years ago. They are cold - blooded animals belonging to the phylum chordata of animal kingdom.

CHARACTERSTICS OF CLASS REPTILIA  They are mostly terrestrial animals and their body is covered by dry and cornified skin , epidermal scales or scutes.The body is divisible into head , neck , trunk and tail.These have two pairs of pentadacty! limbs. Each digit ends into a claw in lizards. Limbs are absent in snakes.Endoskeleton is mainly formed of bones. Skull is monocondylic.. They breath through lungs.Heart is usually three - chambered , but four - chambered in crocodiles.There are 12 pairs of cranial nerves._Ear is formed of internal ear , middle ear and external auditory canal of external ear.Middle ear has only one ear - ossicle (stapes).Kidneys are excretory organs and are metanephros and mostly uricotelic.These are poikilothermal animals , so hibernate in winter.

Sexes are unisexual and show sexual dimorphism.Fertilization is internal.Male lizards have copulatory organs called hemipenis, while male crocodiles and turtles have penis.Female is generally oviparous but some are viviparous (e.g; Rat Snake).Egg is polylecithal ( yolky ), shelled and cledoic ( self sufficient).

 

EXAMPLES OF CLASS REPTILIA:

SOME INTERESTING FACTS ABOUT REPTILES

Herpetology:- Study of reptiles.

Ophiology:- Study of snakes.

Saurology:- Study of lizards.

 

Snakes and lizards shed their scales as skin cast.Jacobson organs are additional smelling organs of reptiles and are present in the roof of buccal cavity.

 

A) MCQ.:-

 

Q1.Study of reptiles is known as:

(a) Serpentology

(b) Herpetology

(c) Ichthyology

(d) None of these

 

Q2.The respiratory organ in reptiles is:

(a) Gills

(b) Epidermis

(c) Skin

(d) Lungs

 

Q3.The larva of frog is:

(a) Trochophore

(b) Tadpole

(C) Ammocoetes

(d) Tornaria

 

Q4.The skull of frog is:

(a) Tricondylic

(b) Monocondylic

(c) Dicondylic

(d) Polycondylic

 

Q5.An animal having pentadacty| limbs without claws belongs to the class :

(a) Amphibia

(b) Reptiles

(c) Aves

(d) Mammalia

 

B) FILL IN THE BLANKS :-

1. Study of snakes is called .

2. is the larva of salamander.

3. Amphibians can live both on and in .

 

C) TRUE/FALSE:-

1. Amphibians have thin, moist, glandular and vascular skin.

2. Egg of reptiles is polylecithal, shelled and cledoic.

3. Reptiles have two chambered heart.

 

A) M.C.Q:-

 

1. (B):Herpetology

2. (D):Lungs

3. (B):Tadpole

4. (C):Dicondylic

5. (A):Amphibia

 

 

 

 

B)FILL IN THE BLANKS :-

1. Ophiology

2. Axolotl

3. Land, water

 

C) TRUE/FALSE :-

1. True

2. True

3. False

 

PART -B -SHORT ANSWER TYPE QUESTIONS :

Q1. Why frog is called an amphibious animal?

Q2. Discuss the nature of skin in the amphibians and reptiles?

Q3. Write two terrestrial adaptations in the reptiles?

 

A44

 

The Aves belong to the phylum Chordata of the animal kingdom that comprises the birds' species. Birds are bipedal, feathered and endothermic egg-laying animals. Aves are adapted to fly. They are found worldwide and their size ranges from 5 cm (bee humming bird) to 2.75 m (ostrich). Among the tetrapod classes, birds constitute the largest number of species. There are about 28 orders, 163 families, 1,975

genera, and nearly 9,000 living modern bird species in the world that occupy nearly all habitats on the earth including open oceans. They show courtship, parental care, nest building, migration and territorial behaviour. The birds are the most beautiful among the animals.It is widely believed that birds descended from two-footed, lizard-like reptiles that lived in the Jurassic period some 208 million years ago. Most scientists believe that birds evolved from

saurischian dinosaurs about 145 million years ago.The first truly bird like animal was Archaeopteryx lithographica, which lived during the Jurassic period. Fossils from this animal were found in Germany in the nineteenth century.This 3-foot (1-meter) long animal is considered to be an evolutionary link between the birds and the dinosaurs. It

had teeth and other dinosaurian characteristics, but it also had a feathered body and could fly.; Birds still have many resemblances to reptiles, such as their habit of laying eggs, the possession of scales on their beaks and legs and the arrangement of many internal structures.In the cretaceous period the birds became modernized. Birds are bipedal vertebrates. Their fore limbs are modified into wings. Hind limbs are strong and useful to walk on land.

All these characters are taken into consideration while classification of birds is done.

Birds are cosmopolitan and found in all continents, seas and most islands.Their wide occurrence is due to their power of flight, which enables them to reach places unreachable to other animals. Most of them can fly and a few have lost the power of flight.The birds evolved in the Jurassic period from bipedal dinosaur reptiles.They are often described as ‘glorified reptiles’ because of their resemblances with and origin from the reptiles and magnificent look.

 

1. All birds have a boat-shaped and streamlined body which helps a bird while flying.Boat shaped body reduce the air pressure and reduce the drag of air while flying.Body usually has four divisions: head, neck. unk and tail; neck disproportionally long for balancing and food gathering.The head has a beak, patch of fleshy skin, ear holes, nostrils and eyes.Neck may be small or long. The trunk is divisible into thorax and abdomen. In the thorax fore-limbs are modified into wings.The abdomen bears the hind- limbs which are long and stout bearing usually four or three and rarely two toes.They are warm blooded (homeothermic) animals 1.e., they are able to maintain a constant body temperature.The body temperature is over 100°F which provides high metabolic rate for quick energy supply.They have a pairs of pentadactyi limbs The forelimbs are modified into wings for flight which are worked by powerful breast muscles attached to the sternum.Most of them can fly except flightless birds (e.g., Ostrich). The toes have claws. All birds have horny epidermal scales on their legs.Each fore limb has 1 to 3 digits and each hind limb has 1 to 4 digits.The hind-limbs are adapted for hopping, wading, swimming, perching, walking or swimming, etc.

2. MOUTH e mouth has a wide gap. Upper and lower jaws are covered with horny sheaths and are modified to form strong beaks which lack teeth.Beaks are adapted to various modes of feeding; seed-crushing, fruit-scooping, flesh-tearing,nector-sipping, wood-chiselling, nest-building and so on.There are no teeth and food is swallowed unmasticated.

 

3. FLIGHT MUSCLES e flight muscles on the breast are greatly developed which help in flight.

4.ENDOSKELETON The endoskeleton is bony, but delicate and light.

Endoskeleton is fully ossified (bony) and the long bones are hollow with air cavities (pneumatic) to reduce weight. There is no bone marrow. It makes the body light.- Most of bones are firmly fused together,which help in flight.The skull is monocondylic, i.e., with one occipital condyle.Sternum is large with a median keel for the attachment of flight muscles.Pelvic girdle is synsacrum. They have fused bones in feet, hands and head.

5.DIGESTIVE SYSTEM e alimentary canal leads to the cloacal aperture posteriorly.The alimentary canal has additional chambers, the crop and gizzard.The crop stores and softens the food;

however, the gizzard is muscular and helps in crushing and churning the food.Some bird species, such as pigeon, keep stone in the gizzard to effectively crush grains and seeds.Gall bladder is absent in some seed-eating birds (graminivorous) such as pigeons.

6. HIGH METABOLISM Birds have a very high metabolism. They may consume thirty times the amount of energy as reptiles of similar size.

7. BLOOD SUGAR Birds also have blood sugar concentrations averaging about twice that found in mammals. This elevated blood sugar supports a greater amount of activity.

8. CIRCULATORY SYSTEM vian cardiovascular systems are extremely efficient,enabling birds to withstand cardiopulmonary stresses far beyond what mammals can tolerate.chambered heart. Relative to their size, however, it is large,powerful, and very rapid in beat.A large oxygen supply is required for rapid metabolism and warm-

bloodedness. It is done by an efficient circulatory system.; Sinus venosus is absent. Renal portal system is very much reduced.

Red blood corpuscles are nucleated, oval and biconvex.

9.EXCRETORY SYSTEM The kidneys are metanephric which drain the nitrogenous waste matter into cloaca through the ureters.

Urinary bladder is absent except Rhea Americana (American Rhea— also called “South American Ostrich”. This is the only bird that has urinary bladder). Excreta are passed out at once. This helps in reducing the weight of the body. They nonnally excrete uric acid (Uricotelic). Urine is semisolid.

10. Respiratory system can perform double respiration.Respiration is through lungs.They have small, spongy and inelastic type lung, which is affixed in the dorsal wall of the thorax.Air sacs are connected to lungs to supplement respiration and serve as reservoirs of air.

This system maintains a constant draught of fresh air through the lungs, even during expiration.They may also aid as cooling devices in regulation of the temperature of the body. The larynx does not act as a voice box.Voice is produced by a special organ, the syrinx which lies at the division of the trachea into " bronchi.

Brain is better developed than that of reptiles, of which cerebrum, cerebellum and optic

lobes are quite large.Birds have 12 pairs of cranial nerves.Equilibrium is maintained by well developed cerebellum of the brain.

Most birds seem to lack the sense of smell and have a keen sense of sight that help to see prey and other foods, land marks and resting places while flying high.Olfactory lobes are reduced. The olfactory sacs open by internal nares into the buccal cavity.They have relatively large-sized eyes. Pecten is present in the eyes of birds.In starlings the eyes comprise 15 percent of the head weight; in humans it is only one percent. In most aspects, the avian eye structure resembles that of mammals. The eyes of birds are able to adjust to light about two times as well as those of a twenty-year old person.Each ear consists of three parts: external, middle and internal. Ear has an external opening,

and a large, curved cochlea with organ of corti. Pinna of ear is rudimentary and has single bone in middle ear.

Female has usually well developed single left ovary and oviduct. If right ovary and oviduct are present, they are vestigial (nonfunctional).

Many birds show sexual dimorphism.All birds are oviparous. It leads to reduction of weight which is so essential for flight.Like reptiles birds lay cleidoic eggs

which are  macrolecithal or polylecithal and calcareous which need incubation, at a constant body temperature by parents.Four embryonic membranes (e.g., chorion, amnion, allantois 

and yolk sac) are formed. Development is direct.The testes are paired. Gonoducts lead into cloaca and the fertilization is mternal. Males generally lack copulatory organs. Copulation occurs by cloacal apposition.

11.SPECIAL ABILITIES Many species has adapted navigational abilities. Some shows extraordinary communication and song production. Parental care is well developed.

CLASSIFICATION OF AVES Subclass LArchaeornithes

This class of birds is extinct. They had a toothed beak with a long lizard-like tail. Eg., Archaeopteryx 

Subclass II- Neornithes (Gk : Neos = modern)

GENERAL CHARACTERS Generally beaks of birds are toothless.

These include modern as well as extinct birds. Examples are Penguin, Grey Heron, Kingfisher,Duck etc.The short tail has a terminal pygostyle, on which feathers are semi-circularly arranged.Well-developed sternum bears a distinct keel or carina.The metacarpals and carpals unite to form carpo-metacarpals.Generally 13 or less caudal vertebrae are present.Digits are usually clawed.

 

INTRODUCTION:Animals belonging to class Mammalia are referred to as mammals. Mammals are one of the most evolved species in the animal kingdom categorized under vertebrata) Mammals are amazingly diverse animals.They exhibit advanced characteristics which set them apart from all other animals.Mammals are distributed worldwide can be found on all continents, in all oceans, deserts, and tropical rainforests, polar regions and on many oceanic islands of the world. Mammals are also the only animal group that evolved and become fully suited to live on land and then back to live in the ocean. Whales,Dolphins and Porpoises have all adapted from land-dwelling creatures to a life of swimming and

reproducing in the water. Whales have evolved into the largest mammals.

There are approximately 5,400 mammalian species, ranging in size from the tiny 1-2 inch bumblebee bat to the 108-foot blue whale. These are distributed in 29 orders, 153 families and about 1,200 genera.

[EVOLUTIONATYHISTORY   1 Basic structural body plan is inherited from Therapsid mammal-like reptiles. The modern mammals of today are synapsids which appeared in the Late Permian period.The evolution of mammals passed through many stages since the first appearance of

their synapsid ancestors (descendants of a group called cynodonts) in the late Carboniferous period between 320 and 315 million years ago. They are the only living synapsids as earlier forms became extinct by the Jurassic period. Survival through mammalian evolution was perhaps due to their ability to move and to think more quickly than their Archosaurian counterparts.

Mammals have evolved to exploit a large variety of ecological niches and life history strategies and, in concert, have evolved numerous adaptations to take advantage of different lifestyles. For example,mammals that fly, glide, swim, run, burrow or jump have evolved morphologies like skull and jaw bones

lost or reduced in size and limbs and limb girdles simplified, reduced and less laterally placed that allow them locomotion efficiently. They are characterized by the presence of hairs, three bones in the inner ear and mammary glands through which they feed their younger ones.the class Mammalia They are the most dommant form of animals found in almost all types of habitats. Different species of mammals have evolved to live in nearly all terrestrial and aquatic habitats on the planet. Many species are arboreal. spending most or all of their time in the forest canopy. One group (bats) has even evolved powered flight, which represents only the third time that this ability has evolved in vertebrates (the other two groups being birds and extinct Pterosaurs). Many mammals are partially aquatic, living near lakes,streams, or the coastlines of oceans (e.g., seals, sea lions, walruses, otters, muskrats, and many others).Whales and dolphins are fully aquatic and can be found in all oceans of the world and some rivers.

 

1. BODY DIVERSITY:Mammalia contains a vast diversity of forms. The smallest mammals are found among the shrews and bats, and can weigh as little as 3 grams. The largest mammal and indeed the largest animal to ever inhabit the planet, is the blue whale, which can weigh 160 metric tons (160,000 kg). Thus, there is a 53 million-fold difference in mass between the largest and smallest mammals.

2. HOMEOTHERMAL hese animals are warm blooded so have high metabolic rate.

3. MAMMARY GLANDS They have mammary or milk producing glands (mammary glands). They are the only animals which nourish their young ones with milk.

3. EXOSKELETON They are hairy quadrupeds. They have fur of epidermal hair throughout the body which helps animals adapt to their environment. Hair has several functions, including insulation, colour patterning, and aiding in the sense of touch. Their skin is glandular and possesses oil glands (sebaceous glands), scent (odoriferous) glands and sweat glands (sudoriferous glands).

4. ENDOSKELETON Endoskeleton is mainly bony. The trunk is divided a few, mammals possess seven cervical (neck) into thorax and abdomen. The skull is dicondylic vertebrae. Vertebrae are acoelous type. Ribs are i.e., with two occipital condyles. The bones of the double-headed---capitulum and tuberculum. Paired skull are united with wavy lines called sutures. Except forelimbs and hind limbs are present in mammals.

Limbs are of pentadactyle type and the digits of the limbs are provided with either claw or nail or hoof.

The coelom is divided into four cavities; a pericardial cavity lodging the heart, two pleural cavities each containing the lung and an abdominal cavity having the rest of viscera.

Mouth is bounded by two movable lips. A bony palate is formed by the union of premaxillae, maxillae and palatines that separates the nasal passage from the buccal cavity. Presence of single-boned lower jaws is there, The dower jQV {S00 composed of a pair of bones — the dentaries. The teeth are heterodont, thecodont and diphyodont type. They are heterodont, i.e., possess different types of teeth which are embedded in the sockets of jaws (the codont). These are developed twice during the life-time of the animal (diphyodont), milk and  permanent teeth. Molars are tribosphenic (three-cusped).

kinds of mammals. In general, specializations of The alimentary canal is highly specialized in many the gut accompany herbivorous habits. The intestines of herbivores are typically elongate and of the cecum. Gut opens out into anus.the stomach may also be specialized. AT In ruminant artiodactyls, such as antelopes, deer,and cattle, the stomach has up to four chambers,each with a particular function in the processing of vegetable material. A cecum is common in many herbivores. The cecum is a blind sac at the far end of the small intestine where complex compounds such as cellulose are acted upon by symbiotic SSS bacteria. The vermiform appendix is a diverticulum

 

5. RESPIRATORY SYSTEM The mammals show only pulmonary respiration and respire through lungs. They possess a muscular diaphragm dividing trunk into thorax and abdomen. However, the diaphragms are arguably more advanced than those of birds and definitely more advanced than those of reptiles. What this means is that mammals can breathe and utilize oxygen more efficiently than other vertebrate orders, which,combined with their warm-blooded metabolisms allows for a wider range of activity and the fuller exploitation of available ecosystems. Sound producing organ is larynx which is supported by 4 cartilages.

Mammals show presence of region of the brain known as Neocortex. The brain is well developed divided into large cerebrum,cerebellum and medulla. Cerebral hemispheres are very large, solid and highly convoluted. Corpus callosum connects the two cerebral hemispheres internally. They possess 12 pairs of cranial nerves. Optic lobes are

divided into four lobes called corpora quadrigemina.

6. SENSORY SYSTEM They possess good sense of hearing. Each ear consists of three parts: external, middle and internal.; External fleshy pinna is present in mammals as a part of external ear. Middle ear has 3 bony ear ossicles (malleus-hammer shaped, incus-anvil shaped and stapes-stirrup shaped).These tiny bones transmit sound : vibrations from the tympanic membrane to the inner ear and transform the vibrations into neural impulses that are then processed by the brain.

Interestingly, the malleus and incus of modern mammals evolved from the lower jaw bone of the immediate predecessors of mammals, the "mammal-like reptiles"therapsids.Internal ear has organ of Corti, the actual hearing organ.

Eyes with upper and lower eyelids and - often with eyelashes. Nictitating membrane is translucent and hairless; it is vestigial in higher mammals.Mammals have a four-chambered heart. A four-chambered heart separates oxygenated blood coming from the lungs from the partially deoxygenated blood that heading back to the lungs to be re-

oxygenated. This ensures that mammalian tissues only receive oxygen-rich blood, allowing for more sustained physical activity with fewer intervals of rest. Only left aortic arch is present in the arterial system. The sinus venous and renal portal systems are absent. RBCs are non-nucleated, biconcave and usually circular in form.

Kidneys are metanephric type. The kidneys of mammals have a portion of the nephron called the loop of Henle or nephritic loop, which allows  mammals to produce urine with a high concentration of solutes, higher than that of the blood. Mammals lack a renal portal system: a

system of veins that moves blood from the hind or lower limbs and region of the tail to the kidneys.Renal portal systems are present in all other vertebrates except jawless fishes. There is a single urinary bladder in mammals. Excretion is ureotelic.

Many mammal groups are unisexual and marked by sexual dimorphism as a result of selection for males that can better compete for access to females. Many mammals are seasonal breeders, with environmentalstimuli such as day length, resource intake and temperature dictating when mating occurs. Females of some species store sperm until conditions are favourable, after which their eggs are fertilized. In other mammals, eggs may be fertilized shortly after copulation, but implantation of the embryo into the uterine lining may be delayed (‘delayed implantation’).

7. REPRODUCTIVE SYSTEM Generally testes are present in the scrotal sacs. Male has a copulatory organ called penis and female has clitoris. Gestation period is found i.e., time taken for the  complete development of the embryo. Except egg laying mammals belonging to prototheria, they are viviparous. There are present four embryonic membranes: chorion, amnion, allantois and yolk sac. Except egg laying mammals a well developed placenta is present. Small eggs are devoid of yolk (microlecithal).Fertilization is ternal.

8:.PARENTAL CARE parental care is the utmost. Thus, female mammals invest a great deal of energy caring for each of their offspring, a situation which has important ramifications in many aspects of mammalian evolution, ecology and behavior. Depending upon the species and environmental conditions,male mammals may either provide no care, or may invest some or a great deal of care to their offspring.Care by males often involves defending a territory, resources, or the offspring themselves. Males may also provision females and young with food.

9. COMMUNICATION any mammals are vocal and communicate with one another or with heterospecifics using sound. Vocalizations are used in communication between mother and offspring,between potential mates and in a variety of other social contexts. Vocalizations can communicate individual or group identity, alarm at the presence of a predator, aggression in dominance interactions,territorial defense, and reproductive state.| CLASSIFICATION OF MAMMALS There are three types of mammals, characterized by their method of reproduction All mammals, except for a few, are viviparous, meaning they produce live young instead of laying eggs.Subclass -Prototheria (Greek: protos = first, therion = beast)

 

General Characters

1. They are primitive mammals with some reptilian characters and act as connecting link between reptiles and mammals.

2. This subclass includes four orders of which only Monotremata is the living group, others are extinct. The monotremes, have bird like and reptilian characteristics, such as laying eggs and a cloaca. The mammary glands lack teats.

3. They are confines to Australian region.

4. An example of amonotreme is the platypus with its bird like beak and egg-laying characteristics.The echidnas are the only other monotreme mammals.

 

5. The testes are abdominal. The cloaca receives the openings of urinary bladder, vas deferens and ureters.

6. External pinna absent. Ribs possess single head.

7. In childhood, teeth are present but adults lack teeth.

 

1. A second type of mammal, the marsupial mammal, includes kangaroos,

wallabies, koalas and possums.

2. They have 7 orders.

3. These mammals give birth to underdeveloped embryos, which then climb

from the birth canal into a pouch on the front of the mother's body, where it feeds and continues to grow.

4. Mammary glands and nipples are present.

5. Uterus and vagina are double. Generally have yolk sac placenta.

6. Body in covered with soft fur. Pinna is well developed. Tail is well-developed and helps in balancing.s. Atlas is incomplete and is provided with cartilage in the ventral incomplete side.

Subclass - THERIANS (Greek: therion = beast) ( Placentalia)

Placentalia is a subclass that includes all the higher orders, including humans.These animals are characterized mainly by their foetus being attached to the uterus by a placenta.This subclass includes three infraclasses, of which Pantotheria is extinct.

 

1. The remainder of mammals, which is the majority of mammals, is placental mammals. Female members of this subclass do not lay eggs but give birth to young ones.

2. These mammals develop in the mother's uterus, receiving nutrients

across the placenta. Mammary glands are provided with nipples or teats.

3. Placental mammals include humans, rabbits, squirrels, whales, dogs, cats, cattle, sheep, horses, elephants, shrews and armadillos. Pinna or external ear is present. The ureters open directly into the urinary bladder.

4. At the end of the digestive tract an anus is present. Teeth are present throughout the life period.

 

5. Testes are situated in the scrotum.

1. The young are born as miniature adult and go through a considerable

period of prenatal growth.

2. A highly-organised allantoic placenta attaches firmly with the uterine wall during developmental period.

3. Brain is highly-developed, cerebral hemispheres have well-developed neo-pallial region. The two hemispheres are connected by corpus callosum.

4. The anal and urinogenital apertures are separate.

Let’s see how much we have grasped?

 

(A) VERY SHORT ANSWER TYPE QUESTIONS

1. Eggs of bird are:

(a) Mesolecithal

(b) Telolecithal

(c) Polylecithal

(d) Alecithal

 

2. The body part, which is absent in birds is:

(a) Fore limb

(b) Hind limb

(c) Pectoral girdle

(d) Pelvic girdle

 

3. The sound box of birds is also known as:

(a) Synsacrum

(b) Pygostyle

(c) Syrinx

(d) Larynx

 

4. Which of the following is not a mammalian character?

(a) Presence of milk gland

(b) Skin possessing hair

(c) Two pairs of limbs

(d) Homodont dentition

 

5. Which of the following is an eggtaying mammal?

a) Whale

b) Platypus

c) Penguin

d) Kangaroo

 

6. The bones form wishbones of birds.

7. Duck billed platypus belongs to subclass .

8. The structure which separates the thoracic cavity from the abdominal cavity in mammals is :

9. Archaeopteryx is the connecting link.

10. Birds have light hollow bones and strong muscles.

11. Whale is the largest fish known.

 

(B) SHORT ANSWER TYPE QUESTIONS

1. Why are birds called as “Glorified Reptiles”?

2. Describe the peculiar features of digestive system in a typical bird.

3. Which three important modifications make mammals most suited animal to land?

4. How is circulation characterized in mammals?

 

 

(C) LONG ANSWER TYPE QUESTIONS

1. Enlist general characteristics of class Aves. _

2. Discuss peculiar characteristics of class mammalia with the help of suitable examples.

 

ANSWER KEY: PART-A

1. (c) Polylecithal

2. (a) Forlimb

3. (c) Syrinx

4. (d) Homodont dentition

5. (b) Platypus

6. Clavicles

7. Prototheria

8. Diaphragm

 

9. True

10.True

11. False : Whale is the largest mammal.

A45

 

INTRODUCTION:Phylum CHORDATA has been divided into Sub Phyla:-

Urochordata , Cephalochordata (both of which are referred to as Protochordates)and Vertebrata. Urochordata and Cephalochordata have no classes.Sub Phylum Vertebrata has been further divided into series of classes based on hierarchy of characters.Let us understand the comparison among different classes of sub phylum Vertebrata.

As already studied in previous assignments no. 40 to 44, sub phylum Vertebrata is divided into two sections; Agnathostomata(Without Jaws) and Gnathostomata(With Jaws).There are two classes under Agnatha; Ostracodermi and Cyclostomata.Ostracodermi has become extinct.

Characteristics of class Cyclostomata, has been discussed in assignment no. 41.Section Gnathostomata is divided into two SUPER CLASSES: PISCES and TETRAPODA.Super class PISCES (Fishes) has _ three classes: Placodermi,Chondrichthyes(Cartilegenous) and Osteichthyes(Bony).

Out of these Placodermi has become extinct.Let us see the table for comparison between Chondrichthyes(Cartilegenous) and Osteichthyes(Bony) fishes:

 

COMPARISON: Chondrichthyes(Cartilegenous) & Osteichthyes(Bony) fishes.

Another super class of section Gnathostomata is Tetrapoda ( Animals with Four limbs). It has four classes depending on the hierarchy of characters. These classes are : AMPHIBIA, REPTILIA, AVES and MAMMALIA.

Now let us compare various classes under sub- phylum VERTEBRATA:

a Skin in FISHES is well adapted for protection from injuries and diseases and serves for respiratory, excretory and osmoregulatory functions. It is covered by means of Placoid scales in Cartilagenous fishes and Ctenoid Ganoid/Cycloid scales in bony fishes.AMPHIBIANS have slippery, moist skin rich in mucous glands as compared to dry, scaly skin of reptiles.Class AVES and class MAMMALIA both have dry skin but former lacks glands whereas later possess a number of glands.

 

1.Heart is 2-chambered in PISCES and 3-chambered in AMPHIBIA.In Class REPTILIA, except Crocodile (4-chambered), all other members have 3-chambered heart.Class AVES and MAMMALIA both have 4-chambered heart having 2 auricles and 2 ventricles.

2.a RBC’s are oval, biconvex and nucleated for all classes of vertebrata.

3.Class Pisces and Amphibians both don’t have external ear and middle ear. They possess only one auditory ossicle.Reptiles may have external ear again with only one auditory ossicle.Birds and Mammals both have external ear with birds having only one ear ossicle and mammals have 3 auditory ossicles.

4.Fishes have no lungs as for they show branchial respiration. Class

Chondrichthyes have 5-7 pairs of gill slits without operculum and Class

Oesteichthyes have 4 pairs of gill slits with gill cover.Class Amphibia and class Reptilia have sac like lungs as compared to solid and spongy lungs of birds and mammals.

 

5. Excretion’:Cartilagenous fishes and amphibians are ureotellic, bony fishes are ammonotellic.Reptiles and Birds are uricotellic.Mammals show ureotellism.

6. Gleses= Cloacal aperture is present in all the classes except bony fishes and mammals that possess anus.

7. Body Temyperaiire Up to reptiles in hierarchy all are cold blooded animals,Aves and Mammals are homoiothermic that maintain a constant body temperature.

 

LET US KNOW WHAT WE HAVE LEARNT!

PART: A_ VERY SHORT ANSWER TYPE QUESTIONS:

a) MCQ'S

1. Aves are:

(a) Ammonotelic

(b) Uricopelic

(c) Ureotelic

(d) BothB&C

 

2. The following statement regarding mammals are correct except :

(a) Cloaca is present

(b) External ear pinna present

(c) Non nucleated RBC

(d) Excrete Urea

 

3. Respiration in class Amphbia is by:

(a)Gills

(b)Lungs

(c) Skin

(d)AIl of these

 

4. Which among the following has 4 chamber heart ?

(a)Vipera

(b)Crocodilus

(c) Testudo

(d)Hemidactylus

 

5. Which of the chordate feature, not shared by the non-chordates?

(a)Triplovlastic Body

(b)True coelom

(c) Bilateral Symmetry

(d)Notochord

 

b) FILL UPS:

1. Reptiles are in excretion

2. Bony Fishes are also called

 

ANSWER KEY: PART-A

a) MCQs:-

1. (b)

2. (a)

3. (d)

4. (b)

5. (d)

 

1. Uricotelic

2. Oesteichyes

 

PART:B SHORT ANSWER TYPE QUESTIONS:

1. Differentiate bAy Mammalia & Reptiles based on body temperature and

erythrocytes.

2. Compare between Chondrichthyes and Osteichthyes.

 

PART:C_ LONG ANSWER TYPE QUESTIONS:

1. Differentiate b/w all classes of sub phylum vertebrata.

 

A46

 

INTRODUCTION:

THE DIFFERENT PHYLA OF KINGDOM ANIMALIA:-

Kingdom Animalia constitutes all animals. Amongst the five kingdoms, the largest kingdom is the animal kingdom. Animals are multicellular eukaryotes.Kingdom animalia is further divided into different phyla. These are nothing but divisions in which animals or organisms with the same characteristics are included under them. Apart from the primary distinguishing features of the Animal Kingdom (Eukaryotic, Multicellular, Without Cell Wall and Heterotrophic); each phylum has organisms that have common characteristics. Kingdom Animalia has been classified into Ten Different Phyla, based on their body design or differentiation. The different phyla in the Animal Kingdom or Metazoa or Multicellular Consumers are as follows:

1. Phylum Porifera

2. Phylum Coelenterata or Cnidaria

3. Phylum Platyhelminthes- The Flat Worms

4. Phylum Nemathelminthes or Aschelminthes

5. Phylum Annelida- The Segmented Worms

6. Phylum Arthropoda- The Animals with Jointed Legs and Appendages

7. Phylum Mollusca-The soft bodied or Shelled Animals

8. Phylum Echinodermata-The Spiny Skinned Animals

9. Phylum Hemichordata or Stomochordata

10. Phylum Chordata-The Animals with Notochord

 

COMPARISON OF PHYLA:-All the above phyla are graded in order of increasing complexity of organisation i.e. from simple to complex. They have been grouped into two main categories depending on the presence or absence of notochord.

Given below is the broad classification of Kingdom

 Animalia:-Salient features of different Phyla in the J are compared in the table given below:-

 

LET US KNOW WHAT WE HAVELEARNT!

PART: A VERY SHORT ANSWER QUESTIONS: -

a) Multiple choice Questions:-

 

1) Kingdom Animalia has been classified into:

a) 10 Phyla

b)12 Phyla

c)8Phyla

d)5Phyla

 

 

 

2) Cellular level of organisation is present in:

a) Chordata

b) Annelida

c) Mollusaca

d) Porifera

 

3) Which is the largest animal phylum:

a) Arthropoda

b) Annelida

c) chordata

d) Mollusca

 

4) Outer body Shell is present in:

a) Annelida

b) Platyhelminthes

c) Mollusca

d) Echinodermata

 

b) True or False:-

1) Notochord is present in chordates.

2) Phylum Annelida bears tissue level of organization.

c) Fill in the blanks:-

1) tail is absent in non-chordates.

2) Another name of Phylum Cnidaria is .

3) Animals are broadly classified into and .

 

ANSWER KEY: PART-A

A)VERY SHORT ANSWER QUESTIONS:-

a} Multiple choice Questions: -

1. a) 10 Phyla

2. d) Porifera

3. a) Arthropoda

4. c) Mollusca

 

b} True or False:-

1. True: Notochord, Hollow Dorsal Nerve Cord, Gill Slits and Post Anal

Tail are the diagnostic characteristics of Phylum Chordata.

2. False: The Phylum Annelida has Organ System Level of organisation.

 

c} Fillin the blanks:-

1. Post-anal

2. Coelenterata

3. Chordates and non-chordates

 

A) SHORT ANSWER QUESTIONS:-

1) Name different phyla of kingdom Animalia.

2) Differentiate between chordates and non-chordates .

3) What are chordates? Write the names of various classes of phylum

chordata.

 

B) LONG ANSWER QUESTION:-

1. Discuss salient features of different phyla in Kingdom Animalia.

 

A47

 

INTRODUCTION:Hello students, as we have completed the chapter no. 04 Animal Kingdom,now we will discuss all the questions under this chapter. First of all we will discuss about Differences or comparison type questions.Some of the important differences type questions along with diagrams related with Animal Kingdom are described as given below:

Difference between Bilateral & Radial symmetry.Diploblastic & Triploblastic organisms Notochord & Nerve Chord.Polyp & Medusa.Chordates & Non-Chordates.

 

A48

 

INTRODUCTION:The animal kingdom is a large group that consists of eukaryotic, multicellular organisms that are heterotropic in nature. As such they obtain their nutrition from external sources. In general, animals are divided into two main groups, namely:vertebrates (animals that have a backbone), and invertebrates (animals that lack a

backbone). However, they are divided further into several phyla.

Now we will discuss the “difference type” of questions in this assignment of daily dose.

 

A49

 

RECAPITULATION:Animals are eukaryotic, multicellular, species belonging to the Kingdom Animalia. Every animal has its own unique characteristics. They obtain their energy either by feeding on plants or on other animals. There are millions of species which have been identified, few share similar characteristics while others differ drastically.

 

NCERT EXERCISE QUESTIONS (1 to 8)

 

Q1. What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?

Answer: Convergent evolution, adaptive radiations, animal with vestigial organ etc. may pose difficulties in the process of classification if the common fundamental features are not taken into account like level of organization,symmetry, body plan, body cavity, germ layers.

 

Q2 .If you are given a specimen, what are the steps that you would follow to classify it?

Answer: The given specimen is classified by observing various features like body symmetry, nature of coelom, digestive system, circulatory system, reproduction and development.

 

Q3.How useful is the study of nature of body cavity and coelom in the

classification of animals?

Answer: The nature of body cavity and coelom is very important. It divide the animals into three categories acoelomate, coelomate and pseudocoelomate. The coelom is a space between body wall and gut wall lined by mesoderm. Animals in which body cavity is absent are called acoelomates. Animals possessing coelom are called coelomate e.g. annelids, molluscs, arthropods, echinoderms,hemichordates and chordates. In some animals, body cavity is not lined by

mesoderm, instead, the mesoderm is present as scattered pouches in between the ectoderm and endoderm, such body cavity is called pseudocoelom.

 

Q 6.What peculiar features do you find in parasitic platyhelminthes?

Answer: (a) Parasitic platyhelminthes such as liver fluke, cestoda attached to the bile duct intestine by suckers and cannot move about.

(b) Absence of epidermis and presence of resistance cuticle.

(c) Sense organs are reduced or absent.

(d) Absence of organs of locomotion.

(e) Alimentary absent in tape worm.

(f) It respires anaerobically.

(g) Life history involves two or more hosts and includes larval stages.

 

 

Q7. What are the reasons that you can think of for the arthropods to

constitute the largest group of the animal kingdom?

Answer: (a) Success of arthropods is largely due to their unique cuticle exoskeleton, segmentation and jointed appendages.

(b) The cuticle is composed of proteins, polysaccharides, chitin, calcium phosphate and carbonate. Being tough it protects the arthropods against predator and forms jointed exoskeleton for muscle attachment.

(c) The chitinous wings of the insects enable them to fly and cross barriers which other animals cannot cross.

(d) Striated muscles provide quick movement and tracheal respiration supplies energy rapidly.

(e) Group of segments and the jointed appendages have become specialized for a great variety of functions.

(f) Forms mouth parts for feeding.

 

Q8.Water vascular system is the characteristic of which group of following:

(a) Porifera (b) Ctenophora (c) Echinodermata (d) Chordata

Answer: (a) Porifera

 

A50

 

INTRODUCTION:Hello students, in this Chapter no. 04 -“Animal Kingdom”; the last chapter under Unit no.01-“Diversity in the Living World” we have discussed all the aspects in detail.Now let us do the remaining NCERT exercise questions, 09 to15, in this daily dose assignment.

 

Q7. “All vertebrates are chordates but all chordates are not vertebrates.”Justify the statement.

Answer(7): All the diagnostic characters of Chordates are present in

vertebrates; h Notochord, Dorsal Hollow Nerve Cord, Gill Slits & Post Anal Tail in their embryo. The notochord is partly or fully replaced by a joint vertebral column. Hence all vertebrates are chordates. But there are certain chordates like Herdmania and Amphixious which do not have a vertebral column in any stage of their life cycle. So all chordates are not vertebrates.

 

Q8. How important is the presence of air bladder in Pisces?

Answer (8): Pisces have gas filled swim bladder or air sac. The swim

bladder acts as a buoyancy regulator and enables the fish to stay ata

particular depth without continue swimming. In some bony fishes, swim

bladder is used as lungs for breathing air.

 

Q9. What are the modifications that are observed in birds that help them fly?

Answer (9):

(a) BODY FORM: The body is boat shaped and streamlined. It is divisible into head, neck, trunk and tail.

(b) APPENDAGES: The forelimbs are modified into wings for flight.

(c) SKIN: The skin is thin, dry and having oil gland on the tail. The feathers are highly modified reptilian scales. They conserve body heat, help in flight and provide colouration to the birds.

(d) ENDOSKELETON: Bones are Pneumatic i.e. contain air cavities to reduce weight which help in flight.

(e) SENSE ORGANS: Sense of smell is usually poor. Eyes are usually large and have keen eyesight to see prey, other foods and resting place while flying high.

(f) EXCRETORY SYSTEM: Excretory matter is chiefly uric acid. Urine is

semisolid to conserve water in body. There are no urinary bladders to reduce body weight for flight.

(g) TEMPERATURE: The body temperature is regulated (homoeothermic or

warm blooded) and high. This enables cell in their muscles to work faster and allows muscles to relax more rapidly during flight.

 

Q10. Could the number of eggs or young ones produced by an oviparous

and viviparous mother be equal? Why?

Answer (10): The number of eggs or young ones produced by an oviparous

and viviparous mother is not equal. The oviparous animals produce large number of eggs. This is because in oviparous animals, the development of young ones takes place outside the mother’s body. Their eggs are more prone to environmental conditions and predators. Therefore to overcome the loss, more eggs are produced by oviparous mother. On the other hand, in viviparous organisms, the development of young ones take place inside the mother womb and are less exposed to environmental conditions and predators. Therefore they are less in numbers compared to eggs of oviparous animals.

 

Q11. Segmentation in the body is first observed in which of the following:

(a) platyhelminthes

(b) Aschelminthes

(c) Annelida

(d) Arthropda

Answer(11): (c) Annelida

 

Q 12. Match the following :

A. Operculum (a) Ctenophora

B. Parapodia (b) Mollusca

C. Scales (c) Porifera

D. Comb plates (d) Reptelia

E. Redula (e) Annelida

F. Hair (f) Cyclostomata and Chondrichthyes

G. Choanocytes (g) Mammalia

H. Gill slits (h) Osteichthyes

Answer (12): A(h); B(e); C(d); D(a); E(b); F(g); G(c); H(f)

 

Q 13. Prepare a list of some animals parasitic on human beings:

Answer(13):

Taenia Solium (Pork tape worm)

Schistosoma (Blood Fluke)

Ascaris (Round worm)

Wucherria (Filarial worm)

Ancylostoma (Hook worm)

Pediculus (Head louse)

Fasciola (Liver Fluke)

Chapter 4 Animal Kingdom