ANIMAL DIVERSITY-I (THEORY) by Rus Education · 2020. 5. 27. · ± Animal groups are characterized by mobility, and the presence of a sensory or a nervous system. These systems receive

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*** Students are advised to solve the questions of exercises in the same sequence or as

directed by the faculty members.

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Index : Preparing your own list of Important/Difficult Questions

Instruction to fill

(A) Write down the Question Number you are unable to solve in column A below, by Pen.

(B) After discussing the Questions written in column A with faculties, strike off them in the

manner so that you can see at the time of Revision also, to solve these questions again.

(C) Write down the Question Number you feel are important or good in the column B.

Advantages

1. It is advised to the students that they should prepare a question bank for the revision as it is

very difficult to solve all the questions at the time of revision.

2. Using above index you can prepare and maintain the questions for your revision.

ruseducation beyond boundaries

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INTRODUCTION :

Taxomony (Gr.) - study of nomenclature, classification and their principles. This word was given by

''Candolle'' (Taxis arrangements. Nomos - Law)

HISTORICAL BACKGROUND OF TAXONOMY :

Aristotle : - ''father of zoology ''. (Book : Historia Animalium)

Father of ancient animal Classification. He classified animals into two groups on the basis of their

natural similarities and differences into

(i) Anaima :- Those animals which don't have Red blood or in which RBC are absent e.g. Sponges,

Cnidaria, Mollusca, Arthropoda. Echinodermata like Invertebrates.

(ii) Enaima :- These animals have red blood. This group includes all vertebrated and it has been further

divided into two sub groups.

(a) Vivipara :- It incldues animals which give birth to young-ones e.g. Man, Whale and other mammals.

(b) Ovipara :- It includes animals which lay eggs. e.g. Amphibians, Pisces, Aves, Reptiles etc.

Pliny :- He classified animal into groups : -

(a) Flying (b) Non-flying

John-Ray :- He gave & defined the term '' species'' as the smallest unit of classfication. He gave

''concept of species ''. According to him, the organisms which develop from the similar type of parents,

belong to the same-species.

Mayr : - According to him similar species are those which are capacble of interbreeding in natureal

condtions. Modern definition of species is conied by ''Mayr''.

Binomial system of Nomenclature was devised by Gesparrd-Bauhin. But the detailed information

about Binomial system was given by Linnaeus. In 1758 in the 10th

edition of his book ''Systema

Naturae'' he gave the classification of known 4236 animals and presented the Binomial system of

nomenclature of animal. He is also known as ''Father of Modern-Taxonomy''

In binomial system the name of each animal has two parts. First part has its genus name and second part

has its species name. First letter of genus name must be written in Capital letter and species name is

written in small letters eg. Canis familiaris. In certain species, sub-species are also found. For naming

the sub species three words are used. First name is for genus, second for species and third for sub-

species. The method of nomenclature of Sub-species is termed as the Trinomial nomenclature and it

was given by ''Huxley and Strickland''. eg. Homo sapiens sapiens.

G.L. Cuvier : - Coined the term Phylum.

Julian-Huxley (1940) : - Proposed New systematic.

Engler and Prantl : - Proposed Phylogenetic classification.

Key for identification of animal was developed by John Ray.

Invertebrate and Vertebrate term was given by Lamarck.

Robert Whittaker (1969) : - Proposed Five-Kingdom system classification to show phylogenetic

relationship.


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(1) Monera (2) Protista (3) Fungi (4) Plantae (5) Animalia

Linnaeus classified animal kingdom into 6-classes.

(1) Mammalia (2) Aves (3) Amphibia (4) Insecta (5) Pisces

(6) Vermes

SEQUENCE OF CLASSIFICATION :

Smallest unit of classification is ''Species''. Genus includes various types of species. Family is made

up of various genera. Many families join together to form an Order, many order join together to form a

class and many classes form a Phylum. All the phyla unite to form the largest unit i.e. Kingdom.

Various grouping levels or ranks in classification known as Obligate categories.

e.g. kingdom Phylum Class Order Family Genus Species

Based on this, all animals are included in the animals kingdom groups and written in the following

Hierarchical manner. For example obligate category of man can be written as

TAXA Category

Kingdom Animalia

Phylum Chordata

Class Mammalia

Order Primates

Family Hominidae

Genus Homo

Species Sapiens

IMPORTANT PHYLA :

Storer and Usinger classified whole animal kingdom into 31 phyla. Out of which 10 are major and 21 are minor

phyla. Main phyla are :

1. Protozoa - e.g. Amoeba, Paramoecium etc.

2. Porifera - Sponges etc.

3. Coelenterate - Hydra, Jellyfish etc.

4. Ctenophora (minor phylum) - Beroe etc.

5. Platyhelminthes - Tape worm etc.

6. Nemathelminthes-Nematoda - Ascaris etc.

7. Annelida - Earthworm, Leach etc.

8. Arthropoda - Insects, Scorpion, Fly etc.

9. Mollusca - Snail, Pila, Octopus etc

10. Echinodermata - Star fish etc.

11. Hemichordata - Balanoglossus

12. Chordata - Fish, Snake, Birds, Monkey etc.


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Basis of Classification.

METAZOA :

Animal groups are characterized by mobility, and the presence of a sensory or a nervous system. These

systems receive stimuli from the environment and respond by exhibiting some behaviour.

The only exception are the porifers (pore-bearers) or the sponges. They have no cell that can be

termed as nerve cell.

Like plant life, early animal life also arose in sea.

The animals which live on the sea floor are called Benthonic (e.g., echinoderms, corals and deep sea fishes),

whereas, which swim about actively in sea are called Nektons.

The multicellular eukaryotic organisms with holozoic mode of nutrition are called as metazoans.

Based on complexity of organization, metazoans are further sub-divided into two sub-kingdoms, the

Parazoa and Eumetazoa.

Parazoa : Parazoa includes the sponges in which the cells are loosely aggregated and do not form

tissues or organs.

Eumetazoa : Eumetazoa includes the rest of the animals, the cells are organized into structural and

functional units called as tissues, organs and organ systems.

SYMMETRY :

Two type of symmetry are usually seen in the animals :

(i) Radial symmetry : The animals with radial symmetry are called as Radiata. For example,

Cnidarians (hydra, jellyfish and starfish). Biradial symmetry is present in sea anemone.

For sessile animals, radial symmetry is advantageous, as it allows food to be gathered from all

sides.

They may develop appendages all round the mouth to capture and push prey into it.

Their sensory and nerve coordination surrounds the mouth. We see this in coelenterates.

(ii) Bilateral symmetry : - The animals with bilateral symmetry are called as Bilateria. The body can

be divided into right and left halves in only one plane.

Bilateral symmetry arose when animals on the ocean floor became mobile.

A crawling animal is most likely to encounter food with the end that goes first. So the mouth

developed at this end.

With the mouth, sensory organs and a coordinating brain also development at the front end.

These organs helped in sensing food. So we see how the head, enclosing the brain, became

associated with the mouth end. This is cephalization.

Asymmetric organisms cannot be divided in any plane to produce two equivalent halves.


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Radial symmetyry

Bilateral symmetry

GERM LAYERS

Diploblastic Triploblastic

Mesoglea Ectoderm

Endoderm

Mesoderm

Germ layer give rise to all the tissues/organs of the fully formed individuals. On the basis of germ

layers, animals can be

(i) Diploblastic : In Diploblastic animals the body cells are arranged in two layers, an outer Ectoderm

and an internal Endoderm with an intervening Mesoglea.

(ii) Triploblastic : If the body wall in animals is made up of three germ layer i.e. ectoderm, mesoderm

and endoderm, they are called as triploblastic animals.

BODY PLAN

Animals have three types of body plan :

(i) Cell aggregate : Cell aggregate type of body plan is present in sponges.

(ii) Blind sac : Blind sac type of body plan is present in Platyheiminthes and Coelenterates, where the

alimentary canal has only one opening.

(iii) Tube within tube : Tube within tube type of body plan is present in Nemathelminthes, Annelida,

Arthropoda, Mollusca, Echinoderms Hemichordates and Chordates. The digestive system is a

continuous tube with an opening at each end.


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Tube-within-a-tube body plan has been achieved in two different ways in two evolutionary lines.

In one called the Protostomes, the first opening to develop in the embryonic digestive tube is the

mouth; the anus develops later. This is seen in the annelid, mollusc and arthropod line.

In the other, the Deuterostomes, the anus develops first and the mouth is formed later. This occurs

in the Echinoderms Hemichordates and Chordates (including the vertebrates).

BODY CAVITY OR COELOM

On the basis of coelom, animals can be

(i) Acoelomate : The animals in which the coelom is absent are called as Acoelomates, for example

flatworms. In them the space between ectoderm and endoderm is filled with parenchyma eg.

Platyhelminthes.

(ii) Pseudocoelomate : The body cavity is not completely lined with mesoderm. Instead, the mesoderm

is present as scattered pouches in between the ectoderm and endoderm. Such a body cavity is called

as pseudocoelom e.g roundworm.

(iii) Eucoelomate : The true coelom is a body cavity which arises as a cavity in embryonic mesoderm. In

this case, the mesoderm of the embryo provides a cellular lining, called as coelomic epithelium or

peritoneum, to the cavity. The coelom is filled with coelomic fluid secreted by the peritoneum. The

coelom is found in Arthropods, Molluscs, Annelids, Echinoderms, Hemichordates and Chordates.

True coelom is of two types :

(a) Schizocoelom : It develops by the splitting up of mesoderm. It is found in annelids, arthropods

and molluscs. Body cavity of arthropods is called heamocoel.

(b) Enterocoelom : The mesoderm arises from the wall of the embryonic gut or enteron as hollow

outgrowths or enterocoelomic pouches. It occurs in Echinoderms, Hemichordates and Chordates.

Pseudocoelom

Coelom

Coelomate Pseudocoelomate Acoelomate

Segmentation

In some animals, the body is externally and internally divides into segments or metameres with serial

repetition of atleast some organs. For example, in earthworm, the body shows metameric segmentation

and the phenomenon is known as metamerism.

Notochord

Notochord is mesodermally derived rod-like structure formed on the mid-dorsal surface 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 or Hemichordates.


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BLOOD VASCULAR SYSTEM

Blood vascular system is basically of two types : Open and Closed.

(i) Open type : In open type, the blood is pumped by the heart into the blood vessels that open into

blood spaces (sinuses). There is no capillary system (i.e., most arthropods, some molluscs except

cephalopods and tunicates). These sinuses are actually the body cavitites, and are called haemocoel.

The pressure of the blood is low; it moves slowly between the tissues, and finally, returns to the

heart via the opened veins. In fact, distribution of blood in the tissues is very poorly controlled. The

pigments, which carry oxygen, remain dissolved in blood plasma. Body tissues and visceral organs

exhange respiratory gases, nutrients and waste products, directly with blood.

(ii)Closed type : Many invertebrates and all the vertebrates, including humans, have a closed circulatory

system. In closed type, the blood flows around the body through the specific blood vessels. In

this system, the same blood regularly circulates in the body under high pressure, and returns

back to the heart without leaving the system of tubes. The heart pumps the blood into the aorta,

which branches in the body into the arteries, and in the tissues into the arterioles, to form the

capillary network. The venules of the capillary network carry the blood back to heart via veins

and vena cava. This helps in supplying the nutrients and oxygen to the tissues, and removing

waste materials and caron dioxide from it reveals a comparison between open and closed

circulatory systems.

Comparison of Open and Closed Circulatory Systems

Open System

Closed System

These are usually low pressure systems.

These are usually high pressure systems.

Blood conveyed directly to the organs without

formation of capillaries.

Blood is conveyed directly to the organs through

capillaries.

Distribution of blood to different organs is not well

regulated.

Distribution of blood to different organs is well

regulated.

Blood returns to the heart slowly.

Blood returns to the heart rapidly.

Found in most arthropods, non cephalopod

mollusks and tunicates

Found in cephalopods (octopus, squids) and

vertebrates.


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THE LIVING WORLD

KINGDOMS

FUNGI PLANTAE ANIMALIA

Unicellular

Prokaryotic

Eg. Bacteria,

PPLO

PROTISTA MONERA

Unicellular ;

eukaryotic.

Phylum - Protozoa

Multicellular ; eukaryotic ;

no chlorophyll and no

cellulose cell wall.

Motility and sensitivity

developed. BRANCHES

PARAZOA EUMETAZOA

Tissue or organ-grade of

organization. Mouth and

digestive cavity present.

Cellular grade of organization.

No obvious mouth and digestive

Cavity.

Phylum-Porifera

MESOZOA

Cillated cells only

Eg. Dicyema

(Minute worm like

Parasite of marine

Invertebrate) (On the basis of Symmetry)

DIVISIONS

RADIATA BILATERIA

Organ-grade. Bilateral

Symmetry.Separate

digestive cavity, Triploblastic

Tissue-grade. Radial symmetry

Body cavity and digestive cavity

Common, Diploblastic

Phylum Cnidaria (Coelentrates)

Phylum Ctenophora (Comb jelles) SUBDIVISION

PROTOSTOMIA DEUTEROSTOMIA

Cleavage of zygote radial and Indeterminate.

Anus from or near blastopore.

Mesoderm from wall of archenteron.

Coelom enterocoelic, or secondarily

Schizocoelic.

Cleavage of zygote spiral and determinate.

Mouth from or near blastopore.

Mesoderm from primordial mesodermal

Cells.

Coelom Schizocoelic.

SECTIONS

ACOELOMATA PSEUDOCOELOMATA

Body cavity pseudocoel

Phylum Nematoda

(Round worms)

No body cavity

Phylum Platyhelminthes Phylum Nemertes or

Rhynocoela

(Flat worms) (Ribbon worms)

EUCOELOMATA

True coelom present

Schizocoel

Hemocoel

Phylum Annelida

(Segmented worms)

Phylum Mollusca

(Soft body in hard shell)

Phylum Arthopoda

(Jointed legs)

Phylum Chordata

(Notocord)

Phylum Echinodermata

(Spiny skinned)

Phylum-Hemichordata

(Tongue-worm/Acorn worm)

Eucoelomata

True coelom

Enterocoel


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PHYLUM - PROTOZOA

It is 3rd

largest phylum. One celled performed all the biological activities like multicellular animals. So

they are termed as ''Acellular'' organism, proposd by Dobell.

Protozoans were first studied by Leeuwenhoeck.

And the name Protozoa was coined by Goldfuss.

Study of protozons is known as Protozoology.

They are world wide, Cosmopolitan and mostly Microscopic, Aquatic, Terrestrial, free living (Amoeba)

or parasitic (Plasmodium).

Solitary or colonial (Proterospongia).

Many causes serious diseases or pathogenic.

Protozoans are samll microscopic, Eukaryotic Unicellular, Colourless, Spherical, Oval, Bell shaped,

Spindle shaped slipper like having irregular Symmetry

Level of body organisation of Protozoans is Protoplasmic level.

Consists of uninucleate or multinucleate protoplasm mostly nacked or some have body bounded by

delicate membrane or a firm pellicle/Test/Lorica/shell.

In few groups of protozoa CaCO3 & Silica shell as exoskeleton is found. e.g. Radiolarian group &

Foraminiferan group.

Number of nuclei vary from one to many. Few show nuclear dimorphism. e.g. Paramoecium.

Body performs all necessary biological activity so in them subcellular Physiological division of

Labour is found.

Locomotion by means of (1) Finger-like Pseudopodia e.g. Amoeba

(2) Whip like Flagella e.g. Euglena

(3) Hairy cillia e.g. Paramoecium

(4) By contraction

(5) No locomotory organelles

Nutrition of Protozons are mainly holozoic (Amoeba), Mixotrophic. (Euglena), Parasitic, Saprozoic

(Plasmodium) and Digestion is intracellular take place in food vacuole.

Respiration and Excretion takes place by exchange of gases through body surface. Some excretion may

occur through contractile vacuole.

Nitrogenous waste is Ammonia.

Some fresh water protozoans get rid of excess water through contractile vacuole and phenomenon

known as Osmoregulation. Amoeba has one and Paramoecium has two vacuoles.

Reproduction takes place by

Asexual Sexual

(1) Binary fission (Amoeba) (1) Syngamy (Plasmodium)

(2) Transverse fission (Paramoecium) (2) Conjugation (Paramoecium)

(3) Longitudinal fission (Trypansoma, Euglena)

(4) Multiple fission (Plasmodium)

(5) Budding

Some also form cyst which help in unfavorable condition for reproduction of organism. They do not

have natural death because in unicellular animals there is no division of somatoplasm & germplasm

so these are considered as immortal.


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PHYLUM PORIFERA (Common Name - Sponge)

Ellias proved that sponges are animals.

Robert Grant gave the name Porifera.

Study of sponges is known as Parazoology.

Phylogenetically evolved from choano flagillates (Proterospongia)

Mostly marine but few are found in fresh water also. They are sessile, solitary or colonial. Entire

body with pores i.e. numerous mouthlets Ostia and one opening for exit Osculum.

Sponge have various body form and shapes i.e. Vase shape, cylindrical with radial symmetry

(Leucosolenia), irregular shape (asymmetrical).

Sponges have Cellular level of organisation with two germ layer i.e. Diploblastic and do not posses head

and appendages.


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Body wall consists of

(i) Outer Dermal layer or Pinacoderm

(a) Pinococytes (Flat cell)

(b) Porocytes (oval)

In case of Sycon pinacoderm is divided into exopinacoderm and endopinacoderm.

Endopinacoderm lines the incurrent canal.

(ii) Inner Choanocytic layer or Choanoderm / Gastral layer

Collar cell or Choanocytes (Flagellated)

Characteristic of Porifera

Choanocytes discovered by - H.J. Clark

(iii) Between these two layers gelatinous material Mesenchyme (Mesohyl) is present which is

non-cellular.

It Consist of Amoebocytes = gives rise to different types of cells of both pinacoderm and Choanoderm


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Scleroblast For skeleton

Spongioblast For skeleton

Thesocytes For food storage (Glycogen)

Phagocytes To engulf by phagocytosis

Trophocytes For Distribution of food

Archaeocytes Formation ova & spermatozoa (Totipotant cells)

Collenocytes Connective tissue cell

Chromocytes Pigmented

Myocytes Highly contractile (at osculum)

Gland cells Secrete shiny substance

Germ cells (Sex cells) Form sperm & ova during breeding season.

Amoebocytes

Body wall enclose a large cavity the spongocoel or paragastric cavity.

Choanocytes with flagella is lined in Spongocoel and radial canal.

Ceaselless beating of flagella cause current of water which enter through ostia perforating porocytes and

various canals and enters in spongocoel and finally leave through large aperature osculum.

Canal system : Canal system of porifera helps in nutrition, respiration, excretion and reproduction.

Canal are developed due to folding of inner wall. There are four types of canal systems.

(i) Asconoid

(Simplest canal)

Ingressing water Canal Spongocoel Osculum

Ex. Lencosolenia, Olynthus


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(ii) Syconoid

Ingressing water incurrent canals radial canals dermal ostia prosopyles

apopyles

to outside spongocoel osculum

Ex. Scypha

(iii) Leuconoid

(complex and most efficient canal system)

Ingressing water incurrent canals flagellated

chambers

dermal ostia prosopyles

Apopyles

to outside excurrent canals osculum

Ex. Euspongia Spongilla

(iv) Rhagon

Ex. Larva of Demospongia

Skeleton is internal, consist of tiny calcarious Spicules (calcoblast) or siliceous spicules

(silicoblast) or fine spongin fibre (spongioblast ), or of both located in mesenchyme.

There are four types of spicules in sponges

(1) Monaxon (Usually at osculum) (2) Triaxon

(3) Tetraxon (4) Polyaxon [Hexa - radiated]


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Scleroblat secrets spicules and Spongioblast secrets spongin fibre.

Digestive cavity and mouth is absent. Nutrition is holozoic. Digestion is intracellular and occurs in

food vacuoles of choanocytes.

Food particle is taken by collar cell and pass them to amoebocyte.

Food is stored in thesocytes.

Distribution of food from ingestive cell to other is brought about by the movable amoeboid cell. -

Trophocytes

Respiration and Excretion takes place by diffusion of gases through body surface. Excretory matter is

Ammonia.

Sponges do not have nervous system.

Reproduction takes place by means of

(i) Asexual - By Fragementation,

Regeneration in sponges was demonstrated by Wilson. It is brought about by archacocytes.

By Budding Special cell mass Gemmules containing Archaeocytes.

Also called as Endogenous budding and the process is known as Gemmulation.

(ii) Sexual - Sponges are Hermaphrodite, fertilization internal and cross fertilization, Protogynous

condition is found .

Formation of ova & spermatozoa

(From Archaeocytes) Zygote

Fertilization Internal, takes place

in another sponge through water

current

Free living larva escapes

from osculum

Cleavage Equal and Holoblastic

Segmentation

Sponge (1) Amphiblastula hollow larva (scypha)

Larva Parenchymula Solid larva (Leucosolenia)

(2) Stereogastrula (Euplectella)


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PORIFERA

(On the basis Skeleton divide into three classes)

Classes Calcarea Hexactinellida Demospongia

Skeleton

Choanocytes

Inhabit

Canal system

e.g.

- Calcareous spicules

- Relatively large.

- Exclusively marine in

shallow water

- Ascon or sycon type C.S.

Leucosolenia

(smallest)

*Scypha (Sycon-Urn sponge

Leucilla

Clathrina

Grantia

6 rayed siliceous spicular

(Glass sponge)

Collar cells small

Exchesively marine and

inhabit in deepwater

Leucon type

Euplectella - (Venus flower

basket, Bridal gift in Japan)

Hyalonema - (Glass rope

sponge)

Pheronema -(Bowl sponge)

1 or 4 rayed silicious spicules

or sponging fibre or both

Small collar cells

Marine or fresh water in deep or

shallow water.

Leucon/Rhagon

*Spongia (Euspongia) - (Bath

sponge)

*Spongilla - (Fresh water

sponge)

Ephydatia - (Sulphur sponge)

Freshwater

Cliona - (Boring sponge) harm

ful to Oyster

Hippospongia - (Horse-sponge

or Horny sponge)

Chalina - Marmaid's gloves

Poterion - Neptune's Cup

Oscarella - Skeleton absent

Chondrosina Skeleton absent

Halichondria Bread sponge

Haliclona Finger sponge

Proterospongia = connective link between Protozoa-Porifera

Largest sponge Spheciospongia

Hypothetical simple sponge & between larva & sponge Olynthus

Shrimps ( also called as Spongicola fish) A crustacean, shows commensalisms with Euplectella

* NCERT


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PLYLUM-COELENTERATA

Leuckart coined name Coelenterate.

Hatschek named Cnidaria on the basis of stinging cells. Peyssonal & Trembley established animal

nature of Coelenterata.

Cnidology-Study of cindaria

Mostly marine, few fresh-water (Hydra.) Carnivorous, some are fixed or free floating.

Coelenterates have two types of forms (Dimorphic)

(1) Polyp (2) Medusa

- Cylindrical in shape

- Mostly sessile, but some are motile

- May be solitary or Colonial

- Types of structures : -

Gastrozooids (Hydranth) - For Nutrition

Dactylozooids - For Protection

Gonozooids - For Reproduction

- Umbrella like

- Free swimming

- Always solitary

- Types of structures : -

Phyllozooids - For Protection

Nectophore - For swimming

Gonophore - For Reproduction

Pneumatophores - For Swimming

Aurelia (Medusa) Adamsia (Polyp)

Either or both zooids may occur in a species.

If both forms are found in a group it is called Cormidia.

If both are found in a species, two form alternate in life cycle. (Alternation of generation or Metagenesis)

Group of different types of zooids in polyp or medusa shows polymorphism.

Coelenterates are usually having radial symmetry, Some Anthozoans have Biradial symmetry.

Coelenterates have two Germ layers (1) Ectoderm (2) Endoderm i.e. They are Diploblastic

Coelenterates have Tissue level of organisation.

No head and appendages. The oral end (mouth) often bears slender, flexible process hollow tentacles.

Body wall consists of -

(a) Epidermis (Outer layer) - Formed of 7 different types of cells.

Stinging cells or Nematoblast or Cnidoblast (for offence & defence) characteristic of coelenterata.

Inject Hypnotoxin.


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Interstitial cells (Totipotent and act as reserve to replace worn out cells/germ cells/Nematocyst) ;

Epithelio - muscular cells ; Glandulo muscular cells ; Sensory cells ; Germ cells

(b) Gastrodermis (Inner layer) - Formed of 5-different types of cells such as

Endothelia - muscular cells or Nutritive cells (with food vacuole) ; Interstitial cells ; Sensory cells ;

Nerve cells ; Germ cells

Between these two layers, gelatinous Mesogloea is present which contain free cells. Mesogloea is

secreted by both the above layers.


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Body of coelenterates may be supported by horny or calcareous exoskeleton.

Cavity of the Coelenteron is having single aperture. Mouth serve both purpose i.e. incomplete

digestion tract (Blind sac).

Digestion is Extra-cellular as well as Intracellular i.e. takes place in Coelenteron as well as food

vacuole. Coelenteron is also responsible for distribution of food besides partly digesting it. This dual

role named coelenteron as Gastrovascular cavity.

Respiration and Excretion takes place by diffusion of gases through body surface.

Excretory matter is Ammonia.

Nervous system present both in polyp & medusa and form a loose net work of nerve fibres on either

side of mesogloea (Diffused type). Neurons are non-polar. Sensory cell are also present. Medusa have

sense organ Rhopalia or statocyst/Tentaculocyst.

Sexes may be separate or united. Coelenterates can reproduce Asexually by Budding (Polyp) and by

Sexually-(Medusa).

Gonads have no duct. Fertilization may be External or internal.

Cleavage is Holoblastic.

Development includes larva.

Larva of Obelia Planula (free living) and scyphistoma larva fixed polyp like.

Larva of Aurelia Ephyra , Scyphistoma


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in e

pid

erm

is &

Gas

tro

der

mis

e.g

. T

his

cla

ss h

as t

wo

ty

pes

of

anim

al

(1)

An

emo

nes

- S

kel

eto

n a

bse

nt

*

Ad

am

sia

- s

ea a

nem

on

e

M

etri

diu

m -

Sea

an

emo

ne

(2)

Co

ral

- C

aCO

3 S

kel

eto

n

A

stra

ea -

th

e st

ar c

ora

l

*

Pen

na

tula

- t

he

sea

pen

*

Go

rgo

nia

- t

he

sea

fan

P

tero

ides

- S

ea f

eath

er

R

enil

la -

Sea

pan

sy

T

ub

ipo

ra -

Org

an -

pip

e co

ral

A

lcy

on

ium

- D

ead

man

's f

inger

(S

oft

c

ora

l)

C

ora

lliu

m -

Red

co

ral

(Mo

ong

a)

*

Mea

nd

rin

a -

Bra

in c

ora

l

M

ad

rep

ora

- S

tag

-Horn

co

ral

F

un

gia

- M

ush

room

co

ral

Scy

ph

ozo

a

Ex

clu

siv

ely

mar

ine

M

edu

sa f

orm

is

mo

re c

om

mon

P

oly

p f

orm

red

uce

d o

r ab

sen

t an

d

hav

e

smal

l m

anu

bri

um

V

elu

m a

bse

nt.

[A

cras

ped

ote

]

M

esoglo

ea is

thic

k, g

elat

inous

and c

onta

ins

cells.

Gas

tro

vas

cula

r ca

vit

y u

nd

ivid

ed.

Go

nad

s ar

e E

nd

od

erm

al

and

sh

ed

the

gam

etes

in

to

the

dig

esti

ve

trac

t w

hen

esca

pe

thro

ug

h

the

mo

uth

.

C

nid

ob

last

is

pre

sen

t in

ep

ider

mis

&

Gas

tro

der

mis

e.g*

Au

reli

a

- th

e Je

lly

fi

sh,

Mo

on

ja

lly

,

Lar

va

- E

ph

yra

Rh

izo

sto

ma

- M

any

mo

uth

(P

oly

sto

mu

m)

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an

ea -

Su

n J

elly

Hy

dro

zoa

Fre

sh w

ater

as

wel

l as

mar

ine

Po

lyp

& m

edu

sa o

ften

show

po

lym

orp

his

m

& m

etag

enes

is.

Po

lyp

s w

ith

man

ubri

um

M

edu

sa h

ave

a v

elu

m (

Cra

sped

ote

)

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eso

glo

ea i

s A

cell

ula

r

G

astr

ov

ascu

lar

cav

ity

un

div

ided

.

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onad

s ar

e E

ctoder

mal

an

d sh

ed gam

etes

dir

ectly

in

to th

e su

rroundin

g w

ater

.

C

nid

ob

last

is

pre

sen

t o

nly

in

ep

ider

mis

e.

g.*

Hy

dra

- F

resh

wat

er p

oly

p

*

Ob

elia

- t

he

sea

fur,

(P

oly

p,

Bla

sto

sty

les,

Med

usa

sh

ow

s m

etag

enes

is)

*

Ph

ysa

lia-

the

Port

ugues

e m

an-o

f-w

ar.

(Neu

roto

xic

,

gas

gla

nd

pre

sen

t)

Bo

ug

ain

vil

lea

Vel

lela

- L

ittl

e sa

il

Mil

lip

ora

(S

tin

g c

ora

l)


23

PHYLUM CTENOPHORA :

Ctenophora name was given by Eschescboltz. Commonly called Sea-gooseberries or Comb-

jellies or Sea-walnuts .

Nematoblasts are absent, so they are also called acnidaria

Exclusively marine and pelagic (float on sea surface) and show Bioluminescence.

Body form may be spherical, cylindrical or Pear-shaped.

Body is soft transparent jelly like having

Biradial symmetry with tissue grade body organization.

Triploblastic Mesoglea contains amoeboid mesodermal cells called Colloblast, Amoeboid cells and

smooth muscle cell.

Locomotion takes place by the presence of 8 ciliary comb plates on the body surface.

Special sensory structure statocyst at the opposite end (absoral end) of the mouth is present.

Tentacles may be present or absent. When present, the number of tentacles are 2. They are solid and

possess adhesive cells called as colloblasts (lasso cells).

Digestion is both extracellular and intracellular. These are carnivorous animals

The animals move by cilia, which join together to form comb plates,

there are eight median comb plates forming locomotory organs.

Resp. system, skeletal, circulatory & excretory system are absent.

Nervous system is diffuse type.

All animals are Bisexual. Complex type of sexual reproduction is

found. Metagenesis is absent.

Gonads = endodermal, Fertilization is external.

Regeneration is normally found.

Development is of indirect type. Life cycle involves a free living

Cydippid larval stage.

Cleavage is Holoblastic determinate and unequal.

Asexual reproduction is absent.

Regeneration & paedogenesis is normally found.

Ctenophora is divided into two classes on the basis of presence or absence of tentacles

TENTACULATA (Tentacles present) NUDA (Tentacles absent)

e.g. *Pleurobrachia Beroe - Swimming eye of cat.

Velamen

Cestum Venus's girdle

*Ctenoplana Commensal with Alcyonium.

Hormiphora

Euchlora rubra with cnidoblast (Exception)

Figure : Pleurobrachia


24

PHYLUM PLATYHELMINTHES :

Gagenbaur suggested the name Platyhelminthes. Includes flat worms, free living (terrestrial, fresh

water or marine) or parasitic.

Study of worms causing parasitic infestation in human is Helminthology. Most members of this phylum

are the parasites of vertebrate. Some are found in aquatic habitat.

Body organisation is of organ and organ system level of organisation.

Body is Triploblastic.

Body is Bilaterally symmetrical. Ist bilateral animals.

Anterior and posterior parts are clear. (Ist phylum to have cephalization).

Locomotary organs are absent in these animals but adhesive organs are present like suckers, hook etc.

Epidermis is syncytial and is some times ciliated. On the body wall of parasitic animals a thick cuticle

is present which protects from the digestive-enzymes of the host. It is secreted by Epidermis.

Muscles in the body-wall are mesodermal. Below the epidermis longitudinal, circular and oblique muscles

are present.

Nervous system is Primitive and ladder like having brain ring and 1-3 paired longitudinal nerves

connected at intervals by transverse commissures. Sense organs occur in free living form.

These are acoelomate. In between various organs a solid, loose mesodermal tissue called Mesenchyma

or Parenchyma is present, which helps in transportation of food material.

In Turbellaria and Trematoda classes an incomplete (Blind sac body plan and without anus) digestive

system is present. In animals of class Cestoda, digestive system is completely absent.

Skeleton and circulatory systems are absent. Turgidity of the fluid in the parenchymal meshes

maintains the form of the body (Hydroskeleton)

Animal respire through body surface. Anaerobic respiration in internal parasite like Taenia.


25

Excretory organs are protonephridia or flame-cells. Flame - cells are also termed as the Solenocytes.

They also help in osmoregulation.

All animals of this phylum are Bisexual except Schistosoma (blood fluke). Reproductive system is

complex and well-developed.

Fertilization may be self or cross and internal. Cleavage is spiral & determinate.

Development may be direct or indirect. In indirect development, larva may be one or of more types. In

these animals yolk/vitelline glands are present which provide nutrition to the eggs.

(a) (b)

Figure Platyhelminthes : (a) Tape worm (b) Liver fluke


26

Divided into three classes

Turbellaria Trematoda Cestoda

Free living fresh water or

marine known as Planarians or

Eddy worm.

Body is unsegmented and leaf

like covered by delicate ciliated

epidermis.Rod shaped Rhabdites

in epidermis.

Mouth is often ventral and anus

absent. Alimentary canal is

present. (Branched)

Reproduction - asexual sexual

and shows good power of

regeneration, no larva.

Suckers - absent

e.g.

* Dugesia (Planaria) - fresh water,

Nocturnal, Cannibalism, slow

creeping omnivorous. Sexual

as well as asexual (Transverse

Binary fission), good power of

regeneration. Pharynx can be

everted. Reproduction

Microstomum - Enemy of

Hydra

Gunda

Convoluta - Symbiont on

Zoochlorella and Diatoms, algae.

Endo-Parasite, known as flukes,

or flat worms.

Body-Unsegmented and leaf

like, covered by tegument,

(Fine spines) No epidermis in

adult.

Mouth - anterior & anus is

absent. Alimentary canal-

branched.

Life history - includes larval

stage & involve, more than

one host.

Suckers - for attachment in the

host

e.g.

*Fasciola (Sheep liver flukes)

Cause liver rot disease

Prim. Host - Sheep & Goat

Sec. host Snail (Planorbis ;

Limnea ; Bulinus)

Show polyembryony , Life-

cycle involves, Micacidium,

Sporocyst, Redia, Cercaria and

Metacercaria larval form

Miracidium (free-swimming

larva).

Schistosoma (the blood flukes)

Paragonimus (Lung fluke

worm) (In lungs of man and

pig)

Diplozoon - Ectoparasite on

the gills of fish. (Monogenetic)

Opisthorchis - Human liver

fluk or chinese liver fluk

Endo-Parasite Intestinal parasite,

known as tape worms

Body-Ribbon like, covered by

tegument. No epidermis in

adult

Mouth and Anus absent (food

from body surface). Alimen

tary canal absent.

Life history - includes larval

stage & involve, more than

one host. Each proglottids has

one or two sets of male &

female reproductive organ.

Scolex has suckers & hooks

for attachment

Body divided into scolex, neck

and strobilla of few to

numerous proglottids. No true

segments

*Taenia solium - Pork tapeworm

Prim. Host = Man (cysticercus

in the infective stage)

Sec. Host = Pig (Concosphere is

the infective stage)

Shows multiplication in larva

stage namely

Oncosphere, Hexacanth,

Bladderworm and Cysticercus.

Causes disease Taemiasis or

Cysticercosis.

Taenia saginata - Beef tapeworm

Echinococcus - Dog tapeworm

Hymenolepis - Smallest tapeworm

in man's intestine - 10 cm, 200

proglottids (Monogenetic)

Moniezea - Endoparisite of

ruminates


27

PHYLUM - ASCHELMINTHES (NEMATHELMINTHES OR NEMATODA) :

Grobben gave the name = Aschelminthes

Gagenbaur nameditas as Phylum Nemathelminthes. Phylum includes round worms.

Aquatic, tarrestrial, free-living or parasites.

Animal of this phylum are Cylindrical, tapering at both end without segmentation.

Bilaterally Symmetrical - Triploblastic, Organ-system level and having tube within tube plan.

Anterior end does not show distinct head.

No appendage.

Body wall consist of

Cuticle - Firm, non living, resistant to digestive enzymes of host.

Moult (changed) many times during growth period (usually four times).

Epidermis - Syncytial

Muscle layer - Longitudinal fibres divided into four quadrants. (each with 150 muscle cells)

Body cavity is Pseudocoel (developed from blastocoel) and contain Pseudocoelomic fluid.

High fluid pressure in the pseudocoelom maintains body shape. It is called Hydroskeleton.

Digestive tract is complete and differentiated into mouth, pharynx, intestine & Anus.

Mouth is surrounded by 3 - lips having sensory papillae and amphids. Pharynx is muscular. It is used to

suck food. Intestine is non muscular.


28

Respiration is through body surface by diffusion.

Circulatory system is undeveloped

Nervous system comprises of circum pharyngeal ring (Brain).

Sense organs like Papillae (Tangoreceptors), Amphids (chemoreceptor) are present on lip.

Paired unicellular Phasmids (chemoreceptor) are found near hind end of body.

Excretory system is H-shaped formed by single cell called Renette cell.

Excretory substance is ammonia.

Reproductive system is developed and sexes are generally separate.

Sexual dimorphism is present.

Male is smaller than female and curved from its caudal end.

Male has penial spicule for copulation. Genital tract joins digestive tract to form cloaca.

Female is larger than male and straight. Genital tract open independently. Female lays numerous eggs

with Chitinous shell.

Fertilization is internal and development is mostly direct.

Cleavage is Holoblsatic spiral and determinate type.

Number of cells are fixed from larva to adult such development is known as Eutely.

CLASSIFICATION :

On the basis of caudal receptor or phasmids, Aschelminthes can be divided into 2 classes-

Aschelminthes

Aphasmidia Phasmidia

Class


29

Class Aphasmidia

Members of this class lack phasmid.

Many types of amphids are found.

One pairs of excretory canal are present.

Caudal adhesive glands are found.

Ex.

Enoplus , Desmoscolex , Trilobus , Lapillaria

Class Phasmidia

(i) Phasmid is present.

(ii) Caudal adhesive glands are not found.

(A) Male, (B) Female

Ex Ascaris*

It is parasite of small intestine.

It is also called roundworm.

Rhabditiform larva exists in the life cycle of Ascaris.

Ascaris leads to disease called Ascariasis.

Infective stage of Ascaris to man is embryonated egg with 2 stage juvenile.

Trichinella spiralis (Trichinia worm) : occur in voluntary muscles cause trichinosis.


30

Trichuris trichiura

It is also called whipworm.

It is parasite of large intestine of man.

No larval stage in the life cycle.

It leads to anaemia and Diarrhoea.

Enterobius

It is also called pinworm or seatworm.

It is parasite of human intestine.

It causes enterobiasis.

No intermediate host.

*Ancyclostoma

Cause - Ancyclostomiasis.

It is also called hookworm.

Its larva penetrate through sole of the person.

Live in intestine and suck tissue fluid.

*Wuchereria

It is also filaria worm.

Its life cycle gets completed in two hosts. Man is the primary host, while female culex/Aedes mosquito

is the secondary host.

It leads to a disease called Elephantiasis.

Adult worm blocks lymph duct this leads to swelling of limbs.

Females are ovoviviparous. Female lays juvenile microfilaria.

Infective stage to man is microfilarae.

Dracunculus

They are also called Guinea worm and also referred to as fiery serpent .

They are digenetic, man is the primary host while waterflea (Cyclops) is the secondary host.

Completely eradicated from India (eye worm)

Loa-loa (eye worm)

Found in subdermal connective tissues. Some times they pass across eye ball.

Tabanas fly act as vector.


31

PHYLUM ANNELIDA :

Lamarck coined the term Annelida.

Free living found in moist soil, fresh water, sea or few are parasite.

Body is Soft, elongated, cylindrical or flattened divided into segments or metameres by ring like, grooves

called Annuli.

Symmetry Bilateral, Triploblstic, Organ-system level having tube within tube plan, metamerically

segmented.

Anterior end forms a distinct head with sense organ in few annelids.

Appendages are simple unjointed, and locomotory having Chitinous Setae and Parapodia with setae.

Body wall consist of

(i) Cuticle Thin moist albuminoid cutical allow free exchange of gas.

(ii) Epidermis Single layered epidermis made up of supporting cell, sensory and glandular cell.

(iii) Muscle layer (1) Circular layer, (2) Longitudinal layer. Muscle are smooth/unstriated.

Body wall may have minute chitinous setae.

Locomotion by means of setae or parapodia or both. Absent in leeches

First Protostomi animals.

Body cavity is true coelom lined by mesodermal coelomic epithelium (Schizocoel.)

It is divided by transverse septa into compartment. It is filled with coelomic fluid that contains cells.

As such there is no Skeleton. Fluid filled coelom serves as a hydrostatic skeleton.

Digestive tract is complete, straight and extends through entire body. The gut has both circular and

longitudinal muscles. Few annelids are sanguivorous. Digestive gland are developed for the first time

in Annelida.

Respiration is through moist skin i.e. Cutaneous respiration. Some have gills (branchial respiration).

Circulatory system is closed. Some blood vessels enlarge to act as pumping heart.

(Heart appear first time in annelids)

The blood is red with haemoglobin dissolved in plasma (Erythrocruarin). It has amoeboid corpuscles only.

Few Annelids like Sabella have Chlorocruarin as a respiratory pigment.

Hirudinaria has circulatory system with haemocoelomic system.

Excretory organ is Nephridia. Coiled tubules also helps in osmoregulation.

Exonephric Endonephric

Integumentary

Nephridia

Pharyngeal nephridia

Septal Nephridia

NEPHRIDIA

Excretory matter (1) Ammonia in aquatic form (2) Urea in land form


32

Nervous system consist of a circumentric nerve ring, double, midventral, nerve cord with ganglia.

Sense organ chemoreceptor, photoreceptor & tentacle, palp, eyes may be present.

Sexes may be separate or united. Asexual reproduction by budding or fission. In some cases. Atoke

(asexual), Epitoke (sexual) phenomenon also found (Nereis).

Cleavage is spiral and determinate unequal & holoblastic. Regeneration is usually found. Life history

includes a trochophore larva in few annelids.

Nereis

Inhabits in sea - shore between tide mark, burrower, nocturnal, carnivorous, gregarious, fertilization -

in sea.

Parapodia in each segment except first & last. During breading body divides in two parts.

Anterior asexual part - Atoke and posterior sexual portion Epitoke. This change is known as epitoky.

Annelida


33

Based on presence or absence/of Parapodia, Setae and Sense organs

Polychaeta

1. Almost all are marine

2. Cephalisation is more

distinct. Head with

well developed eyes,

tentacles and olfactory

palps.

3. Setae numerous and are p

parapodia helps in

locomotion and also

in respiration. Suckers

are absent.

4. Clitellum absent

5. Animals unisexual

and gonads are formed

only during breeding

season.

6. Development is

indirect. Larval stage is

called Trochophore.

e.g.*Nereis Sand

worm/clamworm

Aphrodite - Sea

mouse

Arenicola - Lug

worm

Seballa - Peacock

worm

Chaetopterus -

paddle worm

Shows bio-

florescence,

great power of

regeneration.

Eunice - Palalo

worm

Polynoe - Scale

worm

Terebella -

respire by gills

Glycera Smooth

blood worm

Oligochaeta

1. Most of the members

are terrestrial, but

some are aquatic.

2. Cephalisation absent.

No distinct head,

eyes, tentacles and

olfactory palps.

3. Setae for locomotion.

Number of seate is

limited and situated

in setal sac present

in body wall, a

single setae is present

in a bag. Parapodia

& sucker are absent.

4. Clitelium is present

permanently for

cocoon formation.

Fertilization is external

and is held in cocoon.

5. Bisexual or

hermaphrodite

cross fertilisation &

external.

6. Development is

direct. No larva.

e.g.

*Pheretima

Eutyphaeus

Lumbricus European earthworm

Dravida

Megascolex

Largest earth worm

(S. India)

Dero Fresh watered

Nais Fresh watered

Tubifex Blood worm

(Fresh water)

Indicator of organic

loading

Hirudinea

1. Aqatic, terrestrial,

ectoparasite and

sanguivorous.

2. Cephalisation absent.

No distinct head,

eyes, tentacles and

olfactory palps.

3. Parapodia and seate

are absnt. Suckers at

both the ends.

4. Clitellum

(9-11 segments)

develop only in

breeding season.

5. Animals of this class

are bisexual. Fertili-

zation is external.

6. Development is

direct.

Number of segments

are fixed ie. 33

segments. Each

segment subdivided

into numberous

rings. called

''Secondary external

annulation''

Anticoagulant

Hirudin in the saliva

Saw like chitinous

teeth in buccal cavity

Circulation with

haemo-coelomic

system.

Coelom is divide in

tubes having coelomic

fluid and haemoglobin.

A special mesodermal

tissue Botryoidal tissue

made up of adipose

tisssue for fat storage /

supposed to be excretory.

Archiannelida

1. All Marine

2. Cephalistion absent.

No distinct head,

eyes, tentacle present

and olfactory palps.

3. Parapodia and setae

are absent.

4. Clitellum absent.

5. Animals are unisexual

6. Development is

indirect. Larval stage

is called Trochophore.

Segmentation is

Mainly intermal

e.g Polygordius

Connecting-link

between Annelida

& Mollusca (living

fossil) Larva known

as Loven's Larva

Protodrillus

Dinophilus

Nerilla

Echiuridia

without external and

internal segmentation.

Seate are rare and

usually have long

prostomium

or proboscis.

e.g., Bonelia, Echiuris


34

e.g.*Hirudinaria Fresh

water leech

Pontobdella Skate

sucker.

Hirudo Medicinal

leech (Highly

modified)

Glossiphonia

Fresh water leech

Haemadipsa

Terrestrial leech

Haemopis Horse leech

Acanthobdella

Extroparasite with

setae connecting-link

between oligochaeta

Hirudinea

PHYLUM ARTHROPODA :


35

It is the largest phylum in the animal kingdom, including 900,000 species. The largest class is insecta

with 750,000 species. General characters are

They are triploblastic coelomate and bilaterally symmetrical animals.

The body cavity is full of haemolymph (blood) and it's known as haemocoel. The true coelom is restricted to

gonals.

The body is covered by chitinous cuticle, which forms the exoskeleton. Strengthen by deposition of

minerals (Cal. Phosphate & Carbonate).

They have a segmented body, each segement bearing a pair of jointed appendages covered by a jointed

exoskeleton.

Exoskeleton is made of chitinous cuticle that is shed at intervals.

The process of casting off of skin or integument is known as ecdysis or moulting. Chitnnous exoskeleton is

secreted by the underlying epidermis.

The body is divided into head, thorax and abdomen. In some cases the head and thorax is fused to

form cephalothorax.

In insects the thoracic segments have legs and wings, the abdomen has no legs in insects.

Muscles are striated.

Respiratory organs are gills, book gills, book 1st time developed in Arthropoda. lungs or tracheal

system.

Excretion takes place through green glands or malpighan tubules coxal gland.

Excretory matter = Ammonia (Aquatic) ; Uric Acid (Terrestrial) Nephridia (Perpatus)

Sensory structures in arthropods are antennae for perceiving odour, eyes, statocysts or balance organs

and sound receptors (in chirping crickets and cicadas). Eyes are compound. In honey bees, butterflies

and months and insects, the gustatory receptors are present on their feet.

The heart is dorsal pulsatile, many chambered and the circulatory system is open (Haemocoel). Blood

haemolymph colourless.

The central nervous system consists of a circumentric ring formed by paired pre-oral ganglia connected

by commissures to a solid, dorsal ganglionated, ventral nerve chord.

In land arthropods, the fertilization is always internal. Few aquatic has external fert.

Arthropods are oviparous. In some like the scorpion, the eggs hatch within the female body. They bring

forth the young ones alive. They are viviparous.

Advancement Over Annelida

Distinct-head in all species.

Jointed appendages serving a variety of functions.

Jointed exoskeleton for protection and muscle attachment.

Striped muscles arranged in bundles for moving particular parts.

Special respiratory organs such as gills, trachea, book lungs in majority of cases.

Well developed sense organs such as compound eyes, statocysts auditory organs, taste receptors etc.


36

Endocrine glands and pheromone secretion for communication

CLASSIFICATION :

The phylum arthropoda is divided into five classes.

Class 1. Crustacea

The body is divisible into cephalothorax (head + thorax) and abdomen.

Dorsally, the cephalothorax is covered by a thick exoskeletal carapace.

There are present two pairs of anternnae and a pair of stalked compound eyes.

Respiration is carried out either by body surface or by gills.

Excretion takes place usually by antennary glands ( = green glands) Sexes are usually separate. Sexual dimorphism is also seen.

Development is usually indirect

Examples : Palaemon (Prawn), Macrobrachium (Prawn), Atacus (Cray fish), Palinurus

(Lobster), cancer (Crab), Lucifer (Shrimp), Eupagurus (Hermit crab), Oniscus (wood

louse), Daphnia (Water-flea), Cyclops, Balanus (barnacle). Tiny crustaceans such as

Daphnia and Cyclops act as zooplankton which form important link in the food chain in water.

Class 2. Chilopoda

Body is long and segemented, which is divisible in to head and trunk.

Each trunk segment bears a pair of legs. The first pair of legs are modified in to poison claws.

There is a single pair of antennae and ocelli.

There are present many legs.

Respiration occurs by tracheae.

Excretion takes place by Malpighian tubules.

Development is direct

Examples : Scolopendra (Centipede)

Class 3. Diplopoda

Body is divisible into head, thorax and abdomen.

There is a single pair of antennae and ocelli.

Except first thoracic segment, (It does not have legs) each thoracic segment bears a pair of

legs, however each abdominal segment has two pairs of legs

Respiration occurs by tracheae

Excretion takes place by Malpighian tubules

Development is generally direct e.g. julus (Millipede)


37

Class 4. Insecta (Hexapoda) [Largest number of species]

Body is divisible into head, thorax and abdomen.

There is a pair of antennae, and a pair of compound eyes.

The thorax consists of three segments with three pairs of legs and usually two pairs of

wings. Mesothorax has thick and leathery false wings called as tegmina and membranous

metathoracic wings.

The abdomen may consists of ten segments.

Respiration usually takes places by tracheae. (No respiratory pigments).

Heart is tubular and divided into chambers

Malpighian tubules are the excretory organs. Uric acid is chief excretory waste.

Sexes are separate.

Development may be direct or indirect e.g. silverfish, cockroach, bedbug, locust, termites,

butter flies, rat flea, beetle , wasp, aphid, glow worm etc.

Maggot is the larva of Housefly

Insects communicate with each other by ectohormone called as Pheromones. Pheromones

are chemicals secreted to the outside of the body and perceived (as by smell by other

individuals of same species). They help in communication amongst the organisms of same

species.

Ex. Musa domestica House fly

Tachardia lacca (Lacifer) Lac Insect

Dactylopis Cochineal bug

Lytta Blister Beetle

Apis Honey bee

Bombyx Silkworm

Anopheles

Culex

Aedes

Locusta (Locust)


38

The insects may be divided into four groups on the basis of their mode of development.

Insects without Metamorphosis (Ametabolous Development). Certain insects, such as silver fish, does

not undergo metamorphosis. These insects are most primitive and wingless.

There are present three stages in the life history; egg, young and imago (adult)

Insects with gradual Metamorphosis (Paurometabolous Development). In this type of metamaophosis,

the life history includes egg, nymph (young) and imago (adult). The nymph resembles the adult in its

mode of life but differs in structure, the young being without wings. Gradual metamorphosis. Occurs in

cockroaches, grasshoppers, locusts, termites, stick insects, praying mantis, bed bug and lice.

Insects with incomplete Metamorphosis (Hemimetabolous Development). In this type of

metamorphosis the life history includes egg, naiad (young) and imago (adult). The naiad differs from

the adult in both mode of life and structure. Incomplete metamorphosis occurs in dragon flies and may

flies.

Insects Complete Metamorphosis (Holometabolous Development). In this type of metamorphosis the

life history includes egg, larva, pupa and imago (adult). Complete metamorphosis occurs in butterflies,

moth, beetles, house flies, mosquitoes, fleas, honey bees, ants , wasps. The larvae of butterflies and

moths is called caterpillar. The larva of houseflies is known as maggot. The larva of beetles is termed

grub and the larva of mosquito is called wriggler. The young one formed after every moulting is called

as instar. The period between two molting is stadium.

Hypermetabolous. Each larval stage differs from the others in habits, food and mode of living e.g.

Blisterbeetle

Type of Mouthparts in insects

Generally mouth parts of an insect are one labrum, one labium, one hypopharynx, two mandibles and

two maxillae. Following type of mouth parts are found is insects.

Biting and chewing type e.g., Grass-hooppers, cockroaches and crickets.

Piercing and sucking type.e.g. mosquitoes, bedgugs

Chewing and lapping type. Lap means to drink by scooping with tongue and lapper is that which laps

liquid e.g. honey bees.

Sponging type. eg. House fly. (Musca domestica.) It lacks mandibles. Feeds on sugar by dissolving in

saliva and sucking.

Siphoning type e.g. Butterflies and moth. Here the proboscises formed by the modification of

maxilla.

Lac Insect

Lac is produced commercially by an insect Tachardia lacca (Laccifer lacca).

Lac is actually secreted for its protection and not for the food of the insect.

Male insects are winged and structurally complete, but females are degenerated.

Lac or shellac is an exuviate (secretion) of mainly female.

Lac is resinous substance


39

Cochineal Bug

Dactylopis cocccus lives upon cactus. Dead and dried bodies are used for making a dye called cochineal dye.

Blister Beetle

Lytta is a genus of blister beetle. The drug cantheridine is prepared from its blood.

Cantheridine is widely used for healthy growth of hair

Red Ants

Red ants are used for the production of formic acid.

Glow worm

Wingless female and larva of certain beetles like Lymphyris notiluca which emits greenish light. Also yields

luciferin

Honey Bee : A hive consists of a vertical sheet of wax with a number of hexagonal cells for rearing young

bees (brood cells), storing food (storage cells), royal chamber and chamber of themselves.

Bee is a social, polymorphic and colonial insect. It has three main castes queen, drones and workers.

Queen is the only fertile female of the colony which continues to lay eggs for 2 5 years.

Drones are male honey bees. They develop from unfertilized eggs. Drones and virgin queens take part in

nuptial flight. After copulation the drones are not allowed to come back into hive.

Workers are sterile females.


40

Scout bees search for food and intimate the same to worker bees by dances-round dance for less than 75m

and tail wagging dance for longer distances.

Prof. karl von Frisch got Nobel prize 1973 for decoding the language of bee dances. Workers have pollen

collecting apparatus, honey storing mechanism and wax secreting glands.

Young workers secrete royal jelly. Royal jelly is given to queen or potential queens.

Honey contain simple sugars (fructose and levulose), Vitamins and minerals. It is a tonic, laxative and

sweetening agent. True product of honey bee is bees wax.

Class 5. Arachnida

The body is usually divisible into cephalothorax and abdomen.

The cphalothorax bears simple eyes and six pairs of appendages (One pair of chelicerae,

one pair pedipalpi and four pairs of legs)

Antennae are absent.

Respiratory organs are book lungs or trachea or both

Excretion takes place by Malpighian tubules or coxal glands or both

Development is generally direct.

Examples : Scorpion, spider, Tick, Mite, Aranaeus (garden spinder), Palamneus (Scorpion), Buthus

(Scorpion)

Spiders spins the web by means of a secrection of abdominal glands.


41

There are two more classes in the phylum Arthropods. These classes are Onychophora and Merostomata.

Peripatus is an important examples of the class Onychophora, which has characters of Phylum

Annelida and Arthopoda. Hence it is called "connecting link" between annelida and arthropoda . It

breathes by trachea.

*Limulus. (the king crab or horseshoe crab) is good example of class Merostomata which respires with

book gills. The king crab are called "living fossils". A living fossil is a living animal of ancient origin

with many primitive characters.

Larvae of different Arthropods

(a) Bombyx (Slikworm) Caterpillar / Silkworm

(b) Beetles, honey bee Grub

(c) Musca (Housefly) Maggot

(d) Culex, Anopheles Wriggler

(e) Pennaeus (Marine prawn) Mysis, nauplius, protozoea

(f) Cancer (Crab) Megalopa metanauplius, zoea

Arthopoda is the biggest phylum. About 9,00, 000 species are there . Largest class is insecta.

Von Siebold established phylum Arthoropoda.

Arthopods are Aquatic (Freshater/marine), Terrestrial, burrower, parasitic.


42

PHYLUM MOLLUSCA :

It is second largest Phylum.

Mollusca (Soft bodied) are marine or fresh water or terrestrial.

Johnston coined the name Mollusca.

Study of this phylum is known as Malacology & study of shells of molluscan is known as Conchology.

Body is unsegmented with variety of shapes. Neopilina is exceptionally segmented. (connecting link).

Molluscs are usually bilateral. Few are secondarily asymmetrical (snail) due to twisting (Torsion)

during growth.

Triploblastic with Organ system level.

Body wall includes one layered epidermis (usually cilited) with unstripped muscles found in bundles.

Body parts consist of

(i) Head with sense organ. Head is absent in Pelecypoda & Scaphopoda.

(ii) Dorsal visceral mass containing organ system.

(iii) Ventral foot for locomotion.

(iv) Thin fleshy fold or outgrowth of dorsal body wall covers the body. This fold is called mantle or

pallium. It encloses a space mantle or pallial cavity between itself and the body. The mantle

usually secretes an external limy shell. Shell is made up of Calcium carbonate and Concheolin

protein.

Shell may also be internal (Cuttle fish), reduced and even absent (Octopus)

Coelom is greatly reduced. It is represented by cavities in the pericardium, kidneys and gonads.

Space among the viscera contain blood and form haemocoel.

Digestive tract is complete. Buccal cavity contain a rasping organ the Radula, with transverse row of teeth.

Anus opens into the mantle cavity.

Digestive glands are known as hepatopancreas.

Respiration is usually by gills i.e., Ctenidia. But respiration may takes place by body surface also.

Dentalium respire by Mantle.

Pila respire by pulmonary sac on land and by gills in water.

Circulatory system is open. It includes dorsal pulsatile heart and a few arteries that open into sinuses.

Cephalopoda has closed type of circulatory system

Blood has a copper containing, blue respiratory pigment Haemocyanin. Blood is colourless with

amoebocytes.

Excretory system includes 1 or 2 pairs of sac like kidneys, which open into the mantle cavity. Kidney

of molluscans are Metanephridia known as Kaber's organs or Organ of Bojanus. Excretory matter is

ammonia or uric acid.


43

Nervous system comprises three paired ganglia

(1) Cerebral (above the mouth) (2) Pedal (In the foot) (3) Visceral (in visceral mass)

These are inter connected by (1) Commissure (Joins similar ganglia)

(2) Connectives (Joins dissimilar ganglia)

Senses organ includes (1) Eye - Present over a stalk called ommatophore (Gastropoda).

(2) Statocyst/Lithocyst - For equilibrium in foot

(3) Osphradia - Chemoreceptor/Olfactory as well as for testing chemical &

physical nature of water.

Sexes usually separate (snail has ovotestis). Gonads have ducts.

Fertilization may be external or internal.

Cleavage is spiral, determinate, unequal and holoblastic.

Development is - Direct or indirect.

Trochophore is very common larva of Mollusca phylum.

Larva - Glochidium (Fresh water mussel) and Veliger (Pila)

Precious pearl of the size of tennis - ball is made by a mollusk - Tridekna

Nacre layer is called Mother of Pearl . This layer is made up of CaCO3 and choncheolin protein.

Father of pearl industry - Kokichi Mikimoto


44

Molluscs are classified on the basis of shell, Foot, Nervous system and Gills into seven classes


45

Cep

ha

lop

od

a

- M

arin

e

Sh

ell-

Inte

rnal

and r

educe

d it

may

be

exte

rnal

(N

auti

lus)

or

abse

nt

(Oct

op

us)

Red

ula

- P

rese

nt

Foot

- M

odif

ied into

a f

unnel

and

par

tly into

8 o

r 10 s

uck

er

bea

rin

g a

rms

that

su

rro

und

the

mo

uth

Lo

com

oti

on

is

by

exp

elli

ng

wat

er i

n j

et t

hro

ugh

sip

hon

(Jet

pro

pu

lsio

n).

Ink

gla

nd

s in

so

me

squid

s

for

off

ense

an

d d

efen

se.

Wh

en t

he

squid

is

atta

cked

,

it e

mit

s a

cloud

of

ink

y f

luid

thro

ugh

its

sip

ho

n.

This

'sm

ok

e sc

reen

' inte

rfer

es

wit

h t

he

vis

ion

and

chem

ore

cep

tors

of

the

pre

dat

or

and t

her

eby

hel

ps

the

squid

to

esc

ape.

- C

lose

d b

loo

d

ci

rcula

tion

.

- H

ecto

coty

le f

or

sp

erm

tra

nsf

er

- L

arva

abse

nt

e.g.

Sep

ia-C

utt

le f

ish*

10 a

rms

hav

ing

Ch

rom

atoph

ore

s.

Tet

hy

s -

Sea

-fly

Loli

go -

Sq

uid

(Rad

ula

ab

sent)

*O

cto

pu

s -

Dev

il

fish

8 a

rms

Na

uti

lus

- T

iger

shel

l

Pel

ecy

po

da

Biv

alv

ia o

r

La

mel

lib

ran

ch

iata

- M

arin

e/fr

esh

wat

er

Hea

d-A

bse

nt

Sh

ell-

Con

sist

of

two

val

ves

Mo

vab

ly h

ing

ed d

ors

ally

. R

edu

la-A

bse

nt

Fo

ot-

Plo

ugh

or

Wed

ge

shap

ed f

or

bu

rro

win

g

Red

ula

-ab

sent

Larv

a-G

loch

idiu

m

Tro

choph

ore

e.

g.

Un

io-M

uss

el (

fres

h w

ater

)

My

tilu

s-M

uss

el (

mar

ine)

Lam

elli

den

s-m

uss

el

Ost

rea

Ter

edo

-Sh

ip w

orm

.

*P

inct

ad

a-P

earl

oy

ster

s.

Pte

ria

- In

dia

n p

earl

oy

ster

.

Tri

dek

na-H

ighes

t e

conom

ic

val

ue

Pec

ten

- S

call

op

Ga

stro

po

da

- M

arin

e/fr

esh

wat

er

/m

ois

t so

il.

la

rges

t cl

ass.

- em

bry

o g

row

s in

to a

n

asy

mm

etri

cal

adult

du

e

to

twis

tin

g/t

ors

ion

o

f

vis

cera

l m

ass

du

rin

g

dev

elop

men

t. m

outh

&

anu

s li

e on

sam

e si

de.

Hea

d-W

ith

ey

es

&

ten

tacl

es.

Sh

ell

- S

pir

ally

co

iled

R

ad

ula

P

rese

nt

Foo

t -

Lar

ge

& f

lat

Larv

a -

Tro

chop

ho

re

or

Vel

iger

.

e.g. *

Pil

a-A

pple

-sn

ail

(Sh

ell

use

d i

n b

ut-

ton

s)

Cy

pra

ea-O

ld c

urr

ency

Lim

ex-S

lug

(sh

ell

less

)

Hel

ix

Tu

rbin

ella

-Sh

ankh

Do

ris-

Sea

lem

on

Ap

lysi

a-

Sea

har

e*

Pla

no

rbis

-Lan

d s

nai

l

Lym

nea

-Lan

d s

nai

l

Sca

ph

op

od

a

- M

arin

e

Hea

d -

ab

sen

t.

Sh

ell-

Tu

bu

lar,

op

en a

t

both

end

.

Red

ula

-Pre

sent

Foo

t -

Con

ical

and

use

for

dig

gin

g

Larv

a -

Tro

chop

ho

re

e.g.

*D

enta

liu

m-T

usk s

hell.

(R

espir

e by m

antle)

Po

lyp

laco

ph

ora

/

Am

ph

ineu

ra

- M

arin

e

Hea

d -

red

uce

d w

ithou

t

eyes

and

ten

tacl

es.

Sh

ell

- P

rese

nt

or

abse

nt.

8

do

rsal

pla

tes

pre

sent.

(Mult

ival

ved

)

Ra

du

la

Pre

sent

Foo

t -

Red

uce

d/a

bse

nt.

Larv

a-T

roch

oph

ore

e.g.

Ch

iton

-The

coat

of

mai

l sh

ell

(Sea

-mic

a)

C

haet

op

leu

ra-*

Ap

laco

ph

ora

- M

arin

e, W

orm

lik

e

Hea

d-S

mal

l w

itho

ut

eyes

& t

enta

cles

Sh

ell

- A

bse

nt.

Red

ula

- P

rese

nt

Foo

t-R

educe

/ab

sen

t.

Larv

a-T

roch

oph

ore

e.g.

- N

eom

enia

Mo

no

pla

cop

ho

ra

-

M

arin

e, c

om

mon

ch

arac

ter

of

Annel

ida

an

d A

rth

ropod

a.

Hea

d -

Indis

tinct

Sh

ell

- D

om

e-sh

aped

w

ith

man

tle.

Ra

du

la -

Pre

sent

F

oo

t -

Fla

t m

usc

ula

r

Larv

a -

Tro

chop

ho

re

e.g.

- N

eop

ilin

a

L

ivin

g f

oss

ils

C

on

nec

tin

g l

ink

of

A

nn

elid

a an

d

M

oll

usc

a an

d o

nly

s

egm

ente

d m

oll

usk

w

ith n

eph

ridia

.


46

PHYLUM ECHINODERMATA :

Name Echinodermata was given by Jacob Klein.

All are Marine except Synapta similis.

Generally live at bottom and slow moving.

Body shape is star like, cylindrical like, melon-like, disc-like, flower like.

Body unsegmented with bilateral symmetry in larva and radial pentamerous (arranged in five or

multiple) in adult.

Echinoderms are triploblastic with organ - system level of organization

Echinoderms do not have head.

Tube feet (podia) which comes out through radial area i.e. Ambulacral used for locomotion. They are

extended and retracted by variation in hydraulic pressure of fluid in them and by contraction of their

muscle.

Body wall of echinoderms consists of

(i) Epidermis - Single layered & ciliated.

(ii) Dermis - Below the epidermis thick dermis having mesodermal endoskeleton of calcareous plate

(Ossicles). It has spines.

(iii) Muscles - Smooth and lie below dermis.

Minute pincerlike structure pedicellariae comes out through skin. They keep body surface clear of

debris by opening & closing. These are made up of three calcareous plates.

Echinoderms have true Coelom lined by ciliated mesothelium. Enterocoelous contain fluids with free

amoeboid cells called coelomocytes.

Coelom is divided into many tubes and sinuses, which together form 3 systems.


47

(i) A unique water filled ambulacral or water vascular system with tube feet to help in locomotion.

A perforated plate madreporite permits entry of water into ambulacral system which also help in

food and gas transport system. Structures like Pollian vesicle, tiedmann body or recemose, stone

canal are also found in water vascular system.

(ii) Haemal system.

(iii) Perihaemal system.

Respiration takes place by gills called dermal branchiae or papulae in most of Echinoderms like

Starfish, genital bursae in Brittle star, cloacal respiratory trees Sea- Cucumber, Peristomial gills -

Sea urchin. tube - feets also helps in respiration in all Echinoderms

Digestive tract is complete, (incomplete -brittle star).

Circulation system is reduced and open type called haemal system /Perihaemal system. No heart or

pumping vessel.

There is no specialised excretory organ system. Nitrogenous waste (ammonia) diffuses out via gills,

bursae, respiratory tree and tube feet. Amoeboid cells in coelomic fluid also perform excretory

function by absorbing excretory matter.

Nervous system is simple and primitive type includes a Nerve ring and radial nerve cord with simple

sense organ. (No brain)

Echinoderms resemble chordates in early embryonic development.

Echinoderms have separate sexes.

Fertilization is external (no copulation). Life history includes ciliated, bilaterally symmetrical larva

that undergoes metamorphosis and change into a adult (Deuterostome).

Larva

Star fish Bipinnaria, Brittle star Ophiopluteus

Sea urchin Echinopluteus, Sea cucumber Auricularia

Feather star Doliolaria,

Few echinoderms (star fish) have great power of regeneration. They break off their arms for defence

purpose. This phenomenon is known as Autotomy

Echinoderms in angry or frightened state vomits out viscera (internal organ). This phenomenon is

known as Evisceration.

Heart urchin has lophophore (Ciliary structure)


48

Div

ided

in

to F

ive

class

es

Cri

no

idea

Body f

orm

- P

lant li

ke

fixed

wit

h c

irri

.

Arm

s -

Hig

hly

bra

nch

ed

Sp

ines

- A

bse

nt

Ped

icel

lari

ae -

Ab

sen

t

Am

bula

cral

gro

ov

e -

Ora

l an

d c

ilia

ted

Mad

rep

ori

te -

Abse

nt

An

us

Ora

l

Vis

cera

- E

xte

nd

up

to a

rms

Res

pir

atio

n -

Tub

e fe

et

Su

cker

s A

bse

nt

Lar

va

- D

oli

ola

ria

*A

nte

do

n -

Sea

lil

ly

(mo

st p

rim

itiv

e)

Ho

lop

us

Neo

met

ra -

Fea

ther

sta

r

Neo

met

ra -

Fea

ther

sta

r

Ho

loth

uro

idea

Body

fo

rm-L

on

g &

cyli

nd

rica

l

Arm

s -

Ab

sen

t

Sp

ines

Ab

sent

Pad

icel

lari

ae -

Ab

sen

t

Am

bula

cral

gro

ov

e A

bse

nt

Mad

rep

ori

te -

Inte

rnal

An

us

Abo

ral

Vis

cera

- N

o V

isce

ra i

nto

arm

s.

Res

pir

atio

n-C

loac

al t

ree

Su

cker

s P

rese

nt

Lar

va

- A

uri

cula

ria

*C

ucu

ma

ria

- S

ea c

ucu

mb

er

Ho

loth

uri

a

Sy

na

pta

Ech

ino

idea

Body

fo

rm -

Glo

bula

r/d

isc

lik

e.

Arm

s -

Ab

sen

t

Sp

ines

- P

rese

nt

Ped

icel

lari

ae -

Pre

sent

Am

bula

cral

gro

ov

e A

bse

nt

Mad

rep

ori

te -

Abo

ral

An

us

Abo

ral

Vis

cera

- N

o V

isce

ra i

nto

arm

s.

Res

pir

atio

n -

Per

isto

miu

m g

ills

Su

cker

s P

rese

nt

Lar

va

- P

lute

us

Mouth

- w

ith

bit

ing

& c

hew

ing

too

th

app

arat

us

Ari

sto

tle'

s

lan

tern

(M

asti

cati

ng

ap

par

atu

s

wit

h 5

tee

th)

*E

chin

us-

sea

urc

hin

Cly

pea

ster

- C

ake

urc

hin

Ech

ina

rach

inu

s-sa

nd d

oll

ar

Ech

ino

card

ium

-hea

rt u

rch

in

Sa

lmaci

s

Op

hiu

roid

ea

Body

fo

rm -

Fla

t &

sta

r li

ke

Arm

s -

Fiv

e o

r m

ult

iple

of

fiv

e.

Sh

arply

mar

ked

wit

h t

he

cen

tral

dis

c

Sp

ines

- P

rese

nt

Ped

icel

lari

ae -

Ab

sen

t

Am

bula

cral

gro

ov

e -

Not

vis

ible

Mad

rep

ori

te -

Ora

l

An

us

- A

bse

nt

Vis

cera

- N

o V

isce

ra i

nto

arm

s.

Res

pir

atio

n -

Gen

ital

bu

rsae

Su

cker

s A

bse

nt

Lar

va

- O

phio

plu

teu

s

Op

hio

thri

x (

Bri

ttle

sta

r)

*O

ph

iura

Ast

ero

idea

Body

Fla

t &

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49


50

PROTOZOA - HEMICHORDATA

The term Hmichordata was given by Bateson.

Animals of this phylum are all fossorial, and their tunnels are U - shaped.

Body worm like, and soft.

Body is divided into three parts.

A - proboscis B - Collar C - Trunk

Body wall has single layered epidermis. No dermis

Body cavity is enterocoelus, that is divided into Protocoel, Mesocoel and Metacoel.

Mostly ciliary feeders. Complete alimentary canal is present in digestive system. This is straight or

U - shaped.

Circulatory system is open type. Blood is colourless with ameoboid corpuscles.

Heart is dorsal.

Skeletal tissue is absent.

True notochord is absent.

A notochord like structure is found in their buccal cavity, that is called Buccal diverticulum or

Stomochord (a hollow out-growth arises from roof of buccal cavity).


51

Post anal tail is Absent.

Dorsal heart, ventral nerve cord, no respiratory pigment.

Respiration by gills.

Excretion is done by a single glomerulus. This single glomerulus is situated in the proboscis known as

Proboscis gland.

Central nervous system is just like non chordates. Brain is present in the form of nerve - ring.

Mostly animals are unisexual and reproductin is sexual.

Fertilization is external. Cleavage holoblastic.

Development is direct or indirect because some animals have tornaria larva just like bipinnaria

larva or echinodermata in their developmental stages.

Hemichordata is divided into two Classes

(1) Enteropneusta (2) Pterobranchia

e.g. e.g.

*Balanoglossus. (Tongue worm or Acorn worm) Rhabdopleura

*Saccoglossus

Earlies included Hemichordata in Chordata phylum. Hyman (1959) kept in separate phylum

Hemichordata in invertebrates.

Hemichordata is connecting link between Non-Chordata & Chordata.


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ANIMAL DIVERSITY-I (THEORY) by Rus Education · 2020. 5. 27. · ± Animal groups are characterized by mobility, and the presence of a sensory or a nervous system. These systems receive