Animal Kingdom.pdf

DR. Anand Mani
anand_mani16 https://www.anandmani.com/ https://discord.io/anandmani t.me/anandmani001
Animals are multicellular and heterotrophic organisms without cell wall and chlorophyll. Kingdom
Animalia includes 11 major phyla:
1) Porifera
2) Cnidaria
3) Ctenophora
4) Platyhelminthes
5) Aschelminthes
6) Annelida
7) Arthropoda
8) Mollusca
9) Echinodermata
10) Hemichordata
11) Chordata
BASIS OF CLASSIFICATION
1. Levels of organization
Based on this, animals are grouped into three levels:
Cellular level of organization: Here, the cells are arranged as loose cell aggregates. E.g. Porifera.
Tissue level of organization: Here, the cells are arranged into tissues. E.g. Cnidarians and
Ctenophores.
Organ level of organization: Here, tissues are arranged into organs and organs are associated to
organ system. Each system performs a specific physiological function. E.g. Higher animals
(Platyhelminthes to chordates).
Organ systems of different animals show complexities. E.g.
Digestive system is 2 types:
- Incomplete: It has only a single opening that acts as mouth & anus. Seen in Cnidaria and
Platyhelminthes.
- Complete: It has 2 openings (mouth & anus).
Circulatory system is 2 types: open & closed.
2. Body symmetry
It is the arrangement of similar body parts on 2 sides of main axis of the body. Based on
symmetry, animals are 2 types: Asymmetrical and Symmetrical.
Asymmetrical: Here, body cannot be divided into 2 equal halves. E.g. Most Poriferans, Snails etc.
Symmetrical: Here, body can be divided into 2 equal halves. It is 2 types.
- Radial symmetry: Here, body can be divided into 2 equal halves by any plane along centralaxis
(oral-aboral axis) of the body. E.g. some Poriferans, Cnidarians, Ctenophores and Echinoderms
(adult).
- Bilateral symmetry: Here, body can be divided into right & left halves in only one plane. E.g.
Platyhelminthes to Chordata (except adult Echinodermata).
The body of bilaterally symmetrical animal has a dorsal side (upper), a ventral side (lower), left &
right lateral sides, anterior (cephalic) side and posterior (anal or tail) side.
3. Germinal layers (Embryonic layers)
These are layers of embryo from which all the body organs are formed. Based on the number of
germ layers, animals are 2 types- Diploblastic and Triploblastic.
a) Diploblastic animals: 2 germ layers- outer ectoderm and inner endoderm. In between these
layers, an undifferentiated jelly-like layer called mesoglea is present. E.g. Porifera, Cnidaria &
Ctenophora.
b) Triploblastic animals: 3 germ layers- Outer ectoderm, middle mesoderm and inner endoderm.
E.g. Platyhelminthes to Chordata.

DR. Anand Mani
4. Coelom (body cavity)
It is the cavity lined by mesoderm. It is seen between
body wall and gut wall. Coelom separates the
muscles of gut and body wall.
Based on the nature of coelom,
animals are 3 types:
a) Acoelomate: No coelom. The space between
body wall and digestive cavity is filled with matrix
(parenchyma). E.g. Porifera to Platyhelminthes.
b) Pseudocoelomate: False coelom. Here, the body
cavity is not lined by mesoderm. Mesoderm is
scattered pouches. E.g. Aschelminthes.
c) Coelomate: True coelom. Here, the coelom arises from
the mesoderm. Coelom is lined by peritoneal layer and
filled with coelomic fluid. E.g. Annelida to Chordata.
Functions of coelom:
- It accommodates visceral organs.
- Coelomic fluid reduces friction between visceral organs.
- It acts as shock absorber.
Metamerism (segmentation)
It is the phenomenon in which the body or organs is externally and internally divided into
repeated segments (metameres). E.g. Annelids (earthworm etc.), Arthropods.
Notochord
It is a mesodermally derived supporting rod formed on the dorsal side during embryonic
development in some animals. Animals with notochord are called chordates and those without
notochord are called non-chordates.
(a) (b)
Ectoderm
Mesoglea
Endoderm
Mesoderm

DR. Anand Mani
COMPARISON OF DIFFERENT PHYLA (NONCHORDATES)
Features Porifera (Sponges) Cnidaria (Coelenterata)
Ctenophora (Comb
jellies or Sea walnuts)
Grades of
organization
Cellular Tissue Tissue
Symmetry Asymmetrical. Some areradial. Radial Radial
Germ layers Diploblastic Diploblastic Diploblastic
Coelom Acoelomate Acoelomate Acoelomate
Habit and
habitat
Aquatic (mostlymarine).
Sedentary.
Solitary/colonial.
Aquatic (mostly marine).
Sessile/free swimming.
Solitary/colonial.
Exclusively marine.
Solitary pelagic
Digestive
system
Absent.
Intracellular digestion.
Incomplete.
Intracellular extracellular digestion.
Incomplete.
Intracellular and
extracellular digestion.
Respiratory
system
Absent Absent Absent
Circulatory
system
Absent Absent Absent
Reproduction
Asexual (fragmentation)
Sexual.
Hermaphrodite.
Internal fertilization.
Development is indirect.
Polyp reproduces asexually (budding)
and medusa sexually.
Most are separatesexes.
External fertilization.
Only Sexual.
Hermaphrodite.
Unique
features
Water canal(water
transport) system.
Millions ofostia.
Spongocoel canals are lined
with choanocytes (collar cells).
Body is supported by spicules
and spongin fibres.
Tentacles with cnidoblasts.
A gastro-vascular cavity
(coelenteron) with an opening(mouth)
on hypostome.
Polyp Medusa forms are seen.
Some shows alternation of
generation.
Corals have skeleton (CaCO3).
Locomotion is by 8
vertical external rows of
ciliated comb plates.
Tentacles present.
Shows Bioluminescence.
Examples
Sycon (Scypha),
Spongilla (fresh water sponge),
Euspongia (Bath sponge)
Hydra, Obelia, Aurelia, Physalia
(Portugese man of war),Adamsia
(Sea-anemone), Pennatula (Seapen),
Gorgonia (Sea fan),
Meandrina (Brain coral)etc.
Ctenoplana,
Pleurobrachia
Water canal system: Here, water enters through minute pores (ostia) in the body wall into a
central cavity (spongocoel), from where it goes out through osculum. Canal system is used for
food gathering, gas exchange and removal of wastes.
Hermaphrodite: Male and female sex organs are seen in same individual.
Tentacles: Finger-like structures which surrounds the mouth of coelenterates. Used for food capture
defense.
Cnidoblasts (Cnidocytes): These are stinging cells (present on the tentacles and the body) with a
poison-filled capsule called nematocyst. Cnidoblast is used for anchorage, defense and to capture
prey.

DR. Anand Mani
Polyp Medusa: 2 types of body forms in cnidarians.
- Polyp is tubular attached asexual form, with upwardly directed mouth tentacles. E.g. Hydra,
Adamsia.
- Medusa is umbrella like, free-swimming sexual form, with downwardly directed mouth
tentacles. E.g. Aurelia (Jelly fish).
Alternation of generation (Metagenesis): The phenomenon in which polyps produce medusae
asexually and medusae form the polyps sexually. E.g. Obelia.
Bioluminescence: It is the property of some animals to emit light from the body.
Aschelminthes
(Roundworms)
Annelida
(Segmentedor
Ringedworms)
Arthropoda
(Jointlegged animals)
Triploblastic Triploblastic Triploblastic
Features
Platyhelminthes
(Flatworms)
Grades of
organization
Organ Organ system Organ system Organ system
Organ system
Symmetry Bilateral Bilateral Bilateral Bilateral
Germ layers Triploblastic
Coelom Acoelomate Pseudocoelomate Coelomate Coelomate
Habit and
habitat
Mainly aquatic.
Endoparasites.
Some are free-living.
Aquatic and terrestrial.
Free living or parasitic
in plants animals.
Terrestrial, fresh water
or marine.
Free living or parasitic.
Cosmopolitan
Digestive
system
Respiratory
system
Circulatory
system
Reproduction
Unique
features
Examples
Incomplete Complete Complete
Complete. Tubular
alimentary canal with
well-developed
muscular pharynx.
Absent
Absent Absent
Absent Cutaneous respiration.
Some have branchial
(gill) respiration.
Gills/ book gills/
trachea/book lungs
Closed type Open type
Asexual (fragmentation)
and Sexual.
Hermaphrodite.
Internal Fertilization.
Development is indirect
(many larval stages).
Dioecious.
Sexual reproduction.
Internal fertilization.
Development is direct
or indirect
Sexual.
Earthworms leeches
are monoecious.
Neries is dioecious.
Mostly dioecious.
Usually internal
fertilization.
Mostly oviparous.
Development is direct or
indirect.
Unsegmented, dorso-
ventrally flattened body
(except tape worms).
Excretion by Flame
cells (protonephridia).
Hooks suckers in
parasitic forms.
Some absorb nutrients
from the host through
their body surface.
Syncitial epidermis.
Thick cuticle.
An excretory tube to
remove body waste
through excretory pore.
Sexual dimorphism
(females are longer
than males)
True segmentation.
Longitudinal and
circular muscles help
in locomotion.
Locomotory organs are
setae (in earthworm) or
parapodia (in Neries).
Excretion by Nephridia.
Paired ganglia connected
by lateral nerves to a
double ventral nerve
cord.
Jointed appendages.
Body has 3 regions: head,
thorax abdomen.
Body is covered by
chitinous cuticle
(exoskeleton).
Excretion by Malpighian
tubules.
Sensory organs are
antennae, compound
simple eyes, statocysts
(balance organs).
Taenia solium
(Tape worm),
Fasciola (Liver fluke),
Planaria (shows high
regeneration capacity).
Ascaris (Roundworm),
Ancylostoma
(Hookworm),
Wuchereria
(Filarialworm).
Pheretima (earthworm),
Hirudinaria (blood
sucking Leech),
Neries.
Spider, Scorpion, Crab,
Prawn, Insects etc.
Economically important
insects:
Apis, Bombyx, Laccifer.
Vectors: Mosquitoes
(Anopheles, Culex
Aedes), Housefly etc.
Gregarious pest: Locusta.
Living fossil: Limulus
(King crab).

DR. Anand Mani
1) Dioecious: Sexes are separate.
2) Sexual dimorphism: Morphological differences between male and female.
3) Arthropoda is the largest phylum. Over two-thirds of all named species on earth are arthropods.
Features
Mollusca
(Soft-bodied animals)
Echinodermata
(Spiny-skinned animals)
Hemichordata
Grades of
organization
Organ system Organ system Organ system
Symmetry Bilateral Radial (Bilateral in larva) Bilateral
Germ layers Triploblastic Triploblastic Triploblastic
Coelom Coelomate Coelomate Coelomate
Habit and
habitat
Aquatic.
Few are terrestrial.
Exclusively marine. Marine
Digestive
system
Complete
Complete.
Ventral mouth and dorsalanus.
Complete
Respiratory
system
Gills in aq. forms and pulmonary
sac in terrestrialforms.
Dermal branchiae (skin gillsor
papulae) and tube feet.
Gills
Circulatory
system
Open type Reduced and open type. Open type
Reproduction
Dioecious.
Oviparous.
Dioecious.
Ciliated free-swimming larva.
Dioecious.
Development isindirect.
Unique
features
Body has head, visceralmass
(visceral hump) muscular foot.
Head has sensory tentacles.
Univalve or bivalve calcareous
shell. Feather-like gills for
respiration excretion. Mantle
radula are seen.
Body is covered with spines for
protection. Head absent.
Calcareous endoskeleton (ossicles)
present.
Water vascular system present.
Excretory system absent.
Shows autotomy regeneration.
Worm-like cylindrical body
composed of an anterior
proboscis, a collar and a long
trunk.
Excretion by Proboscis gland.
Examples
Pila (Apple Snail), Pinctada
(Pearl Oyster), Sepia (Cuttlefish),
Loligo (Squid), Octopus
(Devil fish), Aplysia (Sea Hare),
Dentalium (Tusk shell),
Chaetopleura (Chiton)
Asterias (Starfish),
Echinus (Sea Urchin),
Echinocardium, Antedon (Sea Lily),
Cucumaria (Sea Cucumber),
Ophiura (Brittle Star)
Balanoglossus (Tongue worm),
Saccoglossus.
1) Mollusca is the second largest phylum.
2) Radula: File-like rasping organ present in the mouth of mollusc s. It is used for feeding.
3) Mantle (Pallium): The membrane which covers visceral mass. Space between the hump and mantle is called mantle
cavity.
4) Water vascular (ambulacral) system: In this system, sea water enters through a porous plate called madreporite
and reaches the radiating canals and tube feet (podia). Its functions are locomotion, respiration, food capture
transport.

DR. Anand Mani
PHYLUM CHORDATA
It includes animals with notochord, dorsal tubular nerve cord and pharyngeal gill slits. Notochord
is a flexible rod located in the mid dorsal line between the alimentary canal and the nerve cord
in the embryo.
Differences between Chordata and NonChordata
Chordata Non-Chordata
1. Notochord is found in the embryonic stage Absent
2. Central nervous system is dorsal, hollow and single Ventral, solid and double
3. Pharyngeal gill slits present Absent
4. Ventral heart Dorsal heart (if present)
5. A post-anal part (tail) ispresent Absent
Phylum Chordata is classified into 3 subphyla: Urochordata, Cephalochordata Vertebrata.
PROTOCHORDATA (ACRANIATA)
VERTEBRATA (CRANIATA)
Urochordata (Tunicata) Cephalochordata
• Notochord present only in
larval tail.
• Body is covered by test made up
of tunicin.
• Exclusively marine.
• Hermaphrodite.
• E.g. Ascidia, Salpa, Doliolum.
• Notochord from head to tail region
and is persistent throughout thelife.
• Fish- Like body.
Exclusively marine.
Sexes are separate.
E.g. Branchiostoma (Amphioxus or
Lancelet).
Possess notochord during the
embryonic period.
• Notochord is replaced by a cartilaginous
or bony vertebral column in the adult.
• Ventral muscular heart.
• Kidneys for excretion osmoregulation
• Paired appendages (fins or limbs).
CLASSIFICATION OF VERTEBRATA
Vertebrata
Division
Agnatha
(lacks jaw)
Class
1. Cyclostomata
Gnathostomata
(bears jaw)
Super Class
Pisces
(bear fins)
Tetrapoda
(bear limbs)
Class
1. Amphibia
2. Reptilia
3. Aves
4. Mammals
Class
1. Chondrichthyes
2. Osteichthyes

DR. Anand Mani
CLASS CYCLOSTOMATA
- All are ectoparasites on some fishes.
- Elongated body without scales and paired fins.
- 6-15 pairs of gill slits for respiration.
- Sucking and circular mouth without jaws.
- Cartilaginous cranium and vertebral column.
- Circulation is closed type.
- Marine, but migrate for spawning to fresh water. After spawning, they die. Their larvae, after
metamorphosis, return to ocean.
E.g. Petromyzon (Lamprey) and Myxine (Hagfish).
SUPERCLASS PISCES(FISHES)
Class Chondricthyes Class Osteichthyes
Marine. Stream-lined body. Predaceous. Marine fresh water. Stream-lined body.
Cartilaginous endoskeleton.
Notochord is persistent throughoutlife.
Bony endoskeleton.
Ventral mouth. Terminal mouth.
Gill slits without operculum. Powerful jaws. 4 pairs of gills covered by operculum on each side.
Skin with placoid scales. Teeth are modified placoid
scales which are backwardlydirected.
Scales are Cycloid, ctenoid etc.
No air bladder. So, they have to swim constantly to
avoid sinking.
Air bladder forbuoyancy.
Poikilotherms (cold-blooded). Poikilotherms (cold-blooded).
Two-chambered heart (one auricle and oneventricle). Two-chambered heart (one auricle and oneventricle).
Sexes are separate. In males, pelvic fins bear claspers.
Internal fertilization. Many of them viviparous.
Sexes are separate. Fertilisation external. Mostly oviparous.
Development is direct.
Examples
Scoliodon (Dogfish), Pristis (Saw fish), Carcharodon
(Great white shark), Trygon (Sting ray- has poison sting),
Torpedo (Electric ray- has electric organ).
Examples
Marine: Exocoetus (flying fish), Hippocampus (seahorse)
Fresh water: Labeo (Rohu), Catla (Katla), Clarias (Magur).
Aquarium: Betta (Fighting fish), Pterophyllum (Angel fish).

DR. Anand Mani
Class Amphibia Class Reptilia Class Aves (Birds) Class Mammalia
They live in aquatic
terrestrial habitats and
need water for breeding.
Dry cornified skin,
epidermal scales orscutes.
Presence of feathers andbeak.
Forelimbs are modified into
wings.
Presence of m ammary
glands (milk producing
glands).
Body has head trunk.
Some have tail.
Moist skin without scales.
Most have 2 pairs of
limbs.
Snakes and lizards shed
their scales as skin cast.
Limbs- 2 pairs (if present).
Crawling mode of
locomotion.
Dry skin without glands except
the oil gland at the base of the
tail. Hind limbs have scales and
are modified for walking,
swimming or clasping tree
branches.
Long, hollow, pneumatic bones.
Skin with hair.
2 pairs of limbs for walking,
running, climbing,
burrowing, swimming or
flying.
Tympanum represents
ear.
Tympanum represents ear. Tympanum represents ear. External ear (Pinnae).
3-chambered heart
(2 auricles + 1 ventricle).
3-chambered heart (but a
septum partially separates
ventricle). Heart is 4-
chambered in crocodiles.
4-chambered heart. 4-chambered heart.
Poikilotherms Poikilotherms Homoiotherms Homoiotherms
Alimentary canal,
urinary reproductive
tracts open into a Cloaca
which opens toexterior.
Well-developed alimentary
canal.
Digestive tract has additional
chambers, the crop gizzard.
Well-developed alimentary
canal.
Dentition is Heterodont,
thecodont diphyodont.
Respiration is by gills (in
larva), lungs skin
Respiration by lungs.
Double respiration.
Air sacs connected to lungs.
Respiration by lungs.
Sexes are separate.
External fertilisation.
Oviparous.
Development isindirect.
Internal fertilisation.
Oviparous.
Development isdirect.
Internal fertilisation.
Oviparous.
Development is direct.
Sexes are separate. Internal
fertilisation. Viviparous
(except Echidna and
Platypus).
Development isdirect.
Examples
Bufo (Toad),
Rana(Frog),
Hyla (Tree frog),
Salamandra (Salamander),
Ichthyophis (Limbless
amphibia)
Examples Chelone
(Turtle), Testudo (Tortoise),
Chameleon (Tree lizard),
Calotes (Garden lizard),
Crocodilus (Crocodile),
Alligator, Hemidactylus
(Wall lizard). Poisonous snakes :
Naja (Cobra), Bangarus
(Krait), Vipera (Viper) etc.
Non-poisonous snakes:
Python etc.
Examples Examples
Corvus (Crow),
Columba (Pigeon),
Psittacula (Parrot),
Struthio (Ostrich),
Pavo (Peacock),
Gullus (Fowl),
Bubo (Owl),
Aptenodytes (Penguin),
Neophron (Vulture) etc.
Ornithorhynchus (Platypus ),
Macropus (Kangaroo),
Pteropus (flying fox),
Camelus (Camel),
Macaca (Monkey),
Rattus (Rat), Canis (dog),
Felis (Cat), Elephas
(Elephant), Equus (Horse),
Delphinus (Common dolphin),
Balaenoptera (blue whale),
Panthera tigris (Tiger),
Panthera leo (lion)
SUPERCLASS TETRAPODA
- Poik ilotherms (Cold-blooded animals): Animals that lack the capacity to regulate their body
temperature.
- Homoiotherms (warm-blooded animals): Animals having ability to maintain a constant body
temperature.

Echinodermata
PHYLUM-
ECHINODERMATA
. Organ system, Coelomate,
Radial Symmetry.
. Sping bodied.
. Endoskeleton of Calcareous
Ossicles.
. Water Vascular system
present.
Eg:- Starfish, Sea urchin etc.
PHYLUM-
HEMICHORDATA
Hemichordate
. Organ System, Coelomate,
Bilateral symmetry.
. Worm - like with proboscis,
collar and trunk.
. Excretory organ - proboscis
gland.
Eg:- Balanoglossus
Saccoglossus
PHYLUM-
CHORDATA
Chordata
. Organ system, Coelomate
Bilateral symmetry.
. dorsal hollow nerve Cord
present.
. Paired pharyngeal gill slits
present.
Sub – Phyla
. Urochordata/ Tunicata
. Cephalochordata.
. Vertebrata.
CLASSIFICATION OF ANIMALS VERTEBRATA [ Notochord replaced by bony/
cartilaginous Vertebral Column]
CYCLOSTOMATA
Class Cyclostomata
. Sucking Circular mouth without
jaws.
. Cartilaginous cranium Vertebral
Column.
. Gill Slits present.
Eg:- Lamprey Hagfish
CHONDRICHTHYES
Class Chondrichthyes
. Cartilaginous fishes.
. Gill slits without operculum.
. Placoid Scales on skin.
. Electric organ (Torpedo) (sting ray)
Poison sting present.
. po
Eg:- Dog fish, Saw fish, etc.
OSTEICHTHYES
AMPHIBIA
. Bony Fishes.
. Gill slits covered by operculum.
. Air bladder present.
Eg:- Flying fish, Rohu, Sea
horse, etc.
Class Amphibia
. Live in aquatic terrestrial
habitats.
. Body divided into head trunk.
. Heart- 3 Chambered.
. Poikilothermous.
Eg:- Toad, frog, Salamander
REPTILIA
Class Reptilia
. Body Covered with scales and
scutes.
. Heart – 3 chambered [except
crocodile].
. Poikilothermous.
Eg:- Cobra, Alligator,
Tortoise, etc.
AVES
Class Aves
. Presence of feathers, beak
wings.
. Bones long hollow- Pneumatic.
. Heart - 4 Chambered.
. Homoiotherms.
Eg:- Crow, Pigeon, Penguin,
etc.
MAMMALIA
Class Mammalia
. Mammary glands present.
. Skin have hair homoiothermous.
. External ear or pinnal present.
Eg:- Platypus (oviparous),
Kangaroo, Blue Whale,
Common Dolphin(Viviparous)
PHYLUM-
CTENOPHORA
Ctenophora
. Tissue level, Acoelomate,
Radial symmetry.
. Comb plates for
locomotion.
. Bioluminescence
Eg:- Pleurobrachia and
Ctenoplana.
PHYLUM-
CNIDARIA
Coelenterate/ Cnidaria
. Tissue Level, Acoelomate,
Radial Symmetry.
. cnidoblasts present.
. Two body forms- Polyp
and Medusa.
. Alternation of
generation,
metagenesis.
Eg:- Sea anemone,
Sea fan and Brain Coral.
PHYLUM-
PORIFERA
Porifera
. Cellular, Acoelomate,
Asymmetrical.
. Body with ostia, spicules
and choanocytes and
canals in walls.
. Hermaphrodite.
Eg:- Sycon, Spongilla
PHYLUM-
ARTHROPODA
Arthropoda
. Largest Phylum.
Bilateral.
. Respiratory organs present.
. Body divided into – head,
thorax and abdomen.
. Jointed appendages.
. Excretory organ - Malpighian
tubules.
Eg:- Scorpio, Butterfly, mosquito
Prawn,etc.
PHYLUM-
MOLLUSCA
Mollusca
. Second Largest phylum.
. Organ system, Coelomate
Bilateral symmetry.
. Body segmented having head,
muscular foot Visceral hump.
. Mouth has radula.
Eg:- Apples nail, Octopus, squid,
etc.
PHYLUM-
ANNEHDA
. Parapodia – Lateral
appendages.
. Nephridia for excretion and
osmoregulation.
Eg:- Earthworm and Leech.
Annelida
Bilateral symmetry.
. Body segmentation-
Metamers.
Aschelminths
PHYLUM-
ASCHELMINTHES
. Organ system,
Pseudocoelomate Bilateral
symmetry.
. Body round, dioecious.
. Digestive system Complete.
. Muscular pharynx.
Eg:- Round worm, Filaria
worm and hook worm.
PHYLUM-
PLATYHELMINTHES
Platyhelminthes
. Organ and organ system,
Acoelomate, Bilateral
symmetry.
. Flat body, hooks suckers.
Flame Cells.
Eg:- Liver fluke Tape
worm
(i) Cellular Level.
(ii) Tissue Level,
(iii) Organ Level/ Organ
system level
(i) Acoelomate.
(ii) Coelomate,
(iii) Pseudocoelomate
ANIMAL KINGDOM
Class Osteichthyes
Cells
Cellular level
Eqithelial
tissue
Layers of
smooth muscle
Organ level
( stomach )
Tissue level
( Eqithelium )
Levels of
Organisation
Symmetry
Diploblastic
and
Triploblastic
Organisation
Coelom
Segmentation
Notochord
Basis of
Classification

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1 ANIMAL KINGDOM (NON-CHORDATA)
Animal Kingdom (Non-Chordata)

 Animal Kingdom covers about 35 phyla, of which 11 are considered to be major phyla.
In major phyla, 10 are from non-chordates and 1 from the chordates.

HABITAT
 The place on the earth, where an animal finds optimum conditions for food and
shelter is called its habitat. Habitat can be defined as the physical and
geometrical space where an organism lives.
 The habitat may be water, soil or earth’s surface. On the basis of their habitat,
animals can be of following types:
1. Terrestrial habitat:
 Animals which live on land or dry earth’s surface, are said to have terrestrial
habitats.
 Terrestrial animals are adapted for following types of habitat modes:
a. Aerial or flying: These animals possess wings and therefore can fly. e.g.,
Birds, bats.
b. Arboreal: These animals mainly live on trees. e.g., Bat, Monkey.
c. Fussorial: These animals live in burrows or underground. e.g., Rabbits, rat,
earthworm etc.

d. Scansorial: These animals can climb on walls, rocks etc. e.g., Wall lizard, flying
squirrel.
e. Cursorial: These animals are adapted to run very fast.
e.g., Tiger, horse, dog etc.
2. Aquatic animals:
 These animals live in water. They may be fresh water or marine water.
 The aquatic animals may further be of following types:
a. Zooplanktons: The animals which flow passively, with water current, on the
surface of water, are called zooplanktons. e.g., many aquatic protozoans,
larvae, crustaceans etc.
b. Nektons: These animals can float actively in water body even against water
current. e.g., many fishes such as sharks, many skates and rays.
c. Benthos: These animals live at the bottom of the water body. e.g., Deep sea
fishes, many echinodermates, sponges and corals.
d. Pelagic: These animals usually live at the surface or water body. These include
both zooplanktons and Nektons.
3. Amphibian
 These animals living on land as well as in water.
HABITS
 Nature of living is called habit. Animals lead various types of life and on this
basis, they are of following types:
a. Solitary animals: Animals which have singly (not in groups). e.g., Taenia,
Earthworm etc.
b. colonial animals: Animals which live in groups and form colony. e.g., Volvox,
honeybee, termites, wasp etc.
c. Gregarious animals: Animals which live in groups, but do not interact with
each other. e.g., locust.
d. Free living animals: Animals, which do not depend on other organisms for food
and shelter and live independently. e.g., cat, dog etc.
e. Parasitic animals: Animals which depends on other living organisms for food
are called parasitic organisms. e.g., Entamoeba, Taenia, Fasciola, Ascaris,
Louse etc.
f. Saprophagous animals: Animals which obtain their food from dead and
decaying organisms and organic matter are called saprophagous animals. e.g.,
house fly etc.
g. Sanguivorous animals: Animals which feed on the blood of other organisms.
e.g., Mosquitoes, Leech etc.
h. Sessile (sedentary) animals: Animals which do not move here and there are
remain immotile, are called sessile organisms. e.g., Herdmania.

i. Motile animals: Animals, which have locomotory organs and can move here and
there, are called motile organisms. e.g., man horse etc.
j. Diurnal animals: Animals, which are active during day time for obtaining their
food, are called diurnal organisms. e.g., man, horse, dog etc.
k. Nocturnal animals: Animals, which are active at night for obtaining food are
called nocturnal animals. e.g., Cockroach etc.
l. Crepuscular animals: Animals which are active at dusk (evening) for obtaining
their food are called crepuscular animals. e.g., rabbit.
m. Vasperal animals: Animals which are active early morning. e.g., Birds.
n. Caprophagous animals: Animals which can eat their own faecal matter to re-
digest it. e.g., Rabbit.
METAZOA
 Animal groups are characterised by mobility and the presence of a sensory or a nervous
system. These systems receive stimuli from the environment and animals respond by
exhibiting some behaviour.
 The only exception is of poriferans (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 those which
swim about actively in sea are called Nektons.
 The multicellular eukaryotic organisms with holozoic mode of nutrition are called
metazoans. Based on complexity of organisation, metazoans are further sub-divided into
two sub-kingdoms, Parazoa and Eumetazoa.
(a) Parazoa: Parazoa include the sponges in which the cells are loosely aggregated and do
not form tissues or organs.
(b) Eumetazoa: Eumetazoa includes the rest of animals in which the cells are organised
into structural and functional units called tissues, organs and organ systems.

1. LEVELS OF ORGANISATION
A. Cellular Level:
 Though all members of Animalia are multicellular,
all of them do not exhibit the same pattern of
organisation of cells.
 For example, in sponges, the cells are arranged as
loose cell aggregates, i.e., they exhibit cellular level
of organisation.
 Some division of labour (activities) occurs among
the cells.
B. Tissue Level:
 In coelenterates and ctenophores, the
arrangement of cells is more complex.
 Here the cells performing the same function are
arranged into tissues, hence it is called tissue level
of organisation.
C. Organ Level:
 A still higher level of organisation, i.e., organ level
is exhibited by members of Platyhelminthes and
other higher phyla where tissues are grouped
together to form organs, each specialised for a
particular function.

D. Organ system level of organisation.
 In animals like Annelids, Arthropods, Molluscs, Echinoderms and Chordates,
organs have associated to form functional systems, each system concerned with a
specific physiological function.
 Organ systems in different groups of animals exhibit various patterns of
complexities.

2. Patterns of Complexities of Various Organ Systems
Organ and organ system levels began in lower animals like platyhelminthes and
aschelminthes but their complexity kept on increasing from lower to higher phyla. These
complexities are quite obvious and can be used as a basis of classification of animals.
(i) Digestive System: The digestive system of animals can be of two types on the basis of
complexity:
(a) Incomplete digestive system: When the digestive system has only a single opening to
the outside of the body that serves as both mouth and anus, it is called an incomplete
digestive system. e.g., Coelenterates, Ctenophores and Platyhelminthes.
(b) Complete digestive system: When the digestive system has two openings; mouth and
anus, it is called complete digestive system. Hence the entry of food and exit of
waste takes place from separate openings. e.g., Aschelminthes to chordates.
(ii) Circulatory System: Similarly, the circulatory system may be of two types:

(a) Open circulatory system: In open type the body cells and tissues are directly
bathed in the blood pumped out of the heart as the blood flows in open spaces. Hence
there is a direct contact and exchange of materials between the blood and body cells.
e.g., Arthropods, non cephalopod molluscs, hemichordates and tunicates.
(b) Closed circulatory system: In this system, the blood circulates through a series of
the blood vessels of varying diameters, i.e., arteries, veins and capillaries without
ever coming in direct contact with the body cells. A series of these vessels maintain
the continuous flow of blood. The exchange of materials between blood and body cells
takes place in the capillaries. e.g., Annelids, Cephalopod molluscs, Chordates.
(iii) Reproductive system: Lower animals like sponges, coelenterates undergo asexual
reproduction along with the sexual reproduction while in higher animals, sexual
reproduction becomes the predominating mode of reproduction.
3. BODY SYMMETRY
The animals can be categorised on the basis of their body symmetry:

(i) Radial symmetry: When any plane passing through the central axis of the body
divides the organism into two identical halves, it is called radial symmetry. The
animals with radial symmetry are put in the group Radiata. For example,
cnidarians (hydra and jelly fish). Biradial symmetry is present in sea anemone,
ctenophores.
(ii) Bilateral symmetry: The animals with bilateral symmetry are put in group
Bilateria. The body can be divided into identical right and left halves in only one
plane. For example, platyhelminthes, annelids, arthropods etc. (platyhelminthes to
chordates).
(iii) Asymmetry: Asymmetric organisms cannot be divided along any plane to produce
two equivalent halves. Sponges are mostly asymmetrical.
4. GERM LAYERS
 Germ layers give rise to all the tissues/organs
of the fully formed individuals. On the basis
of number of germ layers animals can be
(i) Diploblastic: In diploblastic animals, the body
cells are arranged in two layers-an outer
ectoderm and an inner endoderm with an
intervening undifferentiated mesoglea. e.g.
Coelenterates.

(ii) Triploblastic: If the body wall in animals is made of three germ layers i.e.
ectoderm, mesoderm and endoderm, they are called triploblastic animals. e.g.,
Platyhelminthes to chordates.
5. BODY PLAN Though diverse in shape and size, animals have body that fits in one of
the three basic plans:
(i) Cell aggregate type of body plan is present in sponges. They are clusters of cells
with a rudimentary division of labour among them. There are no tissues, or organs.
(ii) Blind sac: Blind sac type of body plan is present in platyhelminthes 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, Echinodermata and Chordata. The
digestive system is a continuous tube with an opening at both end.
6. BODY CAVITY OR COELOM
Presence or absence of cavity between the body wall and the gut wall is very important
for classification.
(i) Acoelomate: The animals in which the coelom is absent are called acoelomates, for
example poriferans, coelenterates, ctenophores, flatworms. In flatworms, the spaces
between various organs are filled with special tissue called parenchyma.
(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 pseudocoelom e.g. in 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 coelomic
epithelium or peritoneum, to the cavity. The coelom is filled with coelomic fluid secreted by the
peritoneum. True coelom is found in annelids, echinoderms and chordates. True coelom is of two
types:
(a) Schizocoelom develops by the splitting up of mesoderm. It is found in annelids,
arthropods and molluscs. Body cavity of arthropods and non-cephalopod molluscs is called
haemocoel.
(b) Enterocoelom: The mesoderm arises from the wall of the embryonic gut or enteron as
hollow outgrowths or enterocoelomic pouches. It occurs in echinoderms and chordates.

7. 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.
 Metameric segmentation is present in annelids only.
8. NOTOCHORD
 Notochord is a mesodermally derived rod-like structure formed on the dorsal
side during embryonic development in some animals. Animals with notochord are
called chordates and those animals which do not have this structure are called
non-chordates, e.g., porifera to echinoderms.

TABLE: Salient Features of Different Phyla in the Animal Kingdom
Phylum Level of
organi-
sation
Symme-
try
Coelom Segmen-
tation
Digestive
System
Circu-
latory
System
Respi-
ratoery
System
Distinctive Features
Porifera Cellular Many Absent Absent Absent Absent Absent Body with pores and canals
in walls.
Coelent-
erata
(Cnidaria)
Tissue Radial Absent Absent Incomplete Absent Absent Cnidoblasts present.
Cteno-
phora
Tissue Radial Absent Absent Incomplete Absent Absent Comb plates for
locomotion.
Platyhel-
minthes
Organ
Organ
system
Bilateral Absent Absent Incomplete Absent Absent Flat body, suckers.
Aschel-
minthes
Organ
system
Bilateral Pseudocoel
omate
Absent Complete Absent Absent Often worm shaped
elongated.
Annelida Organ
system
Bilateral Coelomate Present Complete Present Present Body segmentation like
rings.
Arthro-
poda
Organ
system
Bilateral Coelomate Present Complete Present Present Exoskeleton of cuticle,
jointed appendages.
Mollusca Organ
system
Bilateral Coelomate Absent Complete Present Present External skeleton shell
usually present.
Echino-
dermata
Organ
system
Radial Coelomate Absent Complete Present Present Water vascular system,
radial symmetry.
Hemi-
chordata
Organ
system
Bilateral Coelomate Absent Complete Present Present Worm-like with proboscis,
collar and trunk.
Chordata Organ
system
Bilateral Coelomate Present Complete Present Present Notochord, dorsal hollow
nerve cord, gill slits with
limbs or fins
*Note: Whittekar removed protozoa from animal kingdom kept in kingdom protista.
It is progenator of all metazoans.

1. PHYLUM: PROTOZOA (Unicellular Protists)
 There are about 15,000 species of protozoans known to exist in the world.
 They are microscopic heterotrophic organisms in which a single cell performs all
the vital activities. For this reason, protozoans are also referred to as acellular
organisms.
 They are aquatic (fresh water and marine) and cosmopolitan in distribution. Some
forms are predators and some parasitic.
 The protozoan cell body is either naked, for example, Amoeba, or surrounded by
a non-rigid pellicle. Cellulose is absent in pellicle.
 Some protozoans secrete shells of various inorganic compounds as external
covers (foraminiferans).
 Different types of locomotory structures are found in protozoans. They may
bear flagella (flagellates), cilia (ciliates) or pseudopodia (sarcodines).
 Locomotory structures are absent in the parasitic forms (Sporozoa).
 In them, neurofibrils and contractile myofibrils are present underneath the cell
surface. Most protozoans are free-living and aquatic.

 They are holozoic and feed largely on bacteria, microscopic algae and minute
animals such as rotifers or on other protozoans including members of their own
species.
 Some protozoans are holophytic; they contain chlorophyll and prepare their own
food by photosynthesis (e.g., Euglena). The parasitic protozoans feed on materials
obtained from the hosts (e.g., Monocystis).
 Contractile vacuole is found in almost all fresh-water protozoans for
maintenance of osmotic concentration of cell body. This phenomenon is known
as osmoregulation.
 Contractile vacuole also helps in excretion. Many sporozoan parasites are
relatively harmless, but some are harmful also.
 For instance, Plasmodium vivax and Plasmodium falciparum cause malaria in
humans. Protozoans are generally uninucleate, but all ciliates and many amoeboid
types are multinucleate.
 The pattern of reproduction is also very specialised in different protozoans.
Most sarcodines, flagellates and ciliates show asexual reproduction by binary
fission, multiple fission or even budding.
 Some ciliates, for example, Paramecium reproduces by sexual means in which two
individuals come close to each other and interchange genetic information by a
process known as conjugation.
 There is no gamete formation in such a process. In sporozoa, some stages of life
cycle show formation of gametes, which are morphologically distinct.
Examples: Free living - Euglena, Amoeba, Paramecium, Elphidium etc.
Parasitic - Monocystis, Entamoeba, Plasmodium, Trypanosoma, Giardia etc.
Trypanosoma

2. PHYLUM: PORIFERA (Sponges)
 These are primitive, multicellular, asymmetrical (except Leucosolenia, Scypha) organisms
having cellular level of organisation.
 Most of them are marine and remain attached to rocks (sessile). A few live in fresh
water e.g., Spongilla. Entire body with pores i.e. numerous mouthlets Ostia and one
opening for exit Osculum.
Important characters of phylum porifera:
1. Body wall: The body wall of a common sponge consists of following layers:
(a) Pinacoderm (dermal layer) :
 It is outer cellular layer which consists of
(i) flattened pinacocytes
(ii) oval porocytes.
(b) Choanoderm (gastral layer) :
 It is inner cellular layer which consists of highly specialized flagellated cells called
choanocytes (collar cells).
 They are the characteristic cells of this phylum responsible for ingestion of food,
secretion of mesohyal and differentiation of sex cells.
(c) Mesohyl layer (mesenchyme) :
 Basically, it is a noncellular layer found between pinacoderm and choanoderm. It has fine
dispersed spongin fibres and numerous spicules.
 It also contains amoebocytes (amoeba-like cells) of both pinacoderm and choanoderm.
 Amoebocytes are modified into the following types :
(i) Archaeocytes. They may be converted into other types of cells and are also called
undifferentiated totipotent cells.
(ii) Trophocytes. They provide food to developing cells and are called nurse cells.
(iii)Thesocytes. They store food granules.
(iv) Gland cells. They secrete a slimy substance.
(v) Spongioblasts. They secrete spongin fibres of the mesohyl layer.
(vi) Scleroblasts. They secrete spicules. In calcareous sponges, they are called calcoblasts

and in silicious sponges, they are called silicoblasts.
(vii) Collencytes. They secrete collagen fibers and form connective tissue.
(viii) Myocytes. They form a circular ring around the osculum and help in closing and opening
of the osculum.
(ix) Germ cells They form sperms and ova and develop during breeding season.
(x) Chromocytes. They contain pigment granules and excretory substances.
(xi) Phagocytes. They collect food from choanocytes through their pseudopodia and also
engulf excreta and damaged tissues.
2. The central body cavity of a sponge is called spongocoel or paragastric cavity.
3. The continuous water current flowing through the canal system is very important for the
life of a sponge. It brings in food and oxygen and carries away carbon dioxide,
nitrogenous wastes and reproductive bodies. Thus, the canal system helps the sponge
in nutrition, respiration, excretion and reproduction.
4. Skeleton: Almost all sponges possess an internal skeleton. It may consist of calcareous
or siliceous spicules or of fine spongin fibres or both, located in the mesohyl layer.
5. Digestion: It is intracellular and takes place inside food vacuoles as in protozoans.
6. Circulation: Distribution of food from the ingesting cells to others is brought about by
wandering amoebocytes of mesohyl layer.
7. Respiration: Exchange of gases occurs by diffusion through the plasma membranes of
the cells as in protozoans.
8. Excretion: Removal of metabolic wastes also occurs by diffusion through the plasma
membranes of the cells as in protozoans. Ammonia is chief excretory waste.
9. Nervous System: This is the only phylum in animal kingdom without any nerve cells.
10. Reproduction: They are hermaphrodite and show internal fertilization.
Both asexual and sexual reproduction occur in sponges:
(A) Asexual reproduction: It occurs by fragmentation / budding in unfavourable
condition. Endogenous budding of asexual reproduction in sponge is known as
gemmulation (Special cell mass Gemmules contain Archaeocytes).

(B) Sexual reproduction: They are hermaphrodite, fertilization-internal and cross
(Protogynous condition). After fertilisation, the zygote develops into a flagellated
larva which swims, settles in a new place and grows into a sponge.
11. Development: Zygote undergoes holoblastic cleavage (complete division). The
development is indirect and includes a free-swimming larva, the amphiblastula (in Sycon)
or parenchymula (in Leucosolenia and other Porifers) for dispersal of the species.
CLASSIFICATION - Based on the type of skeleton, Porifera is divided into 3 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
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)
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)
1. Spongin fibres are elongated protein fibres which form a fibrous network.
2. Regeneration in sponges was demonstrated by H.V.Wilson (1907). It is brought about by
archaeocyte cells.
3. Sponge cells, seperated by straining pieces of sponge through a fine net, can reaggregate and
grow into a sponge. So, a sponge is a republic of cells which identify one another, aggregate and
grow together.
4. Proterospongia is a connecting link between protozoa and porifera.
5. Amphiblastula is the hollow larva of Sycon etc. whereas parenchymula is the solid larva of most of
sponges, e.g., Leucosolenia.
Concept Builder

3. PHYLUM: CNIDARIA (Coelenterata)
The phylum Cnidaria (the old name is Coelenterata)
includes about 9,000 species, mainly marine. They are
sessile, free swimming, radially symmetrical
invertebrates and more complex than sponges.
General characters of this phylum are as follows:
1. Cnidarians exhibit a blind sac body plan and are
radially symmetric. They are more advanced than
sponges in having true tissues. They are,
however, acoelomate.
2. Body wall consists of only two cell layers, the
ectoderm and the endoderm, separated by a jelly-
like mesoglea. These animals are therefore
diploblastic, that is, arising from two
embryonic cell layers.
3. Body wall in coelenterates (with reference to Hydra).
They are diploblastic animals i.e., they are derived from two layers-ectoderm and
endoderm. These germ layers form the epidermis and gastrodermis.
(A) Epidermis: The various epidermal cells are:
(a) Epithelio-muscular cells: Each cell has two functional parts, the outer epithelial
part, extending to the body surface and the basal muscular part drawn out into two
muscle processes along the longitudinal axis of the body. The muscle processes
contain a contractile fibril myoneme.
(b) Glandulo-muscular cells: The epithelio-muscle cells, chiefly in the region of the
pedal disc, are especially modified to secrete sticky material for attachment of
animal to substratum.
(c) Interstitial cells: They are totipotent cells which give rise to all the different cells
of the body.
(d) Sensory cells: They are scattered throughout the epidermis. They are most
numerous on the tentacles, hypostome and basal disc. They receive and transmit
impulses.

(e) Nerve cells: They occur for the first time in coelentrates. They are present at the
base of epithelio-muscle cells. They conduct impulses in all the directions.
(f) Germ cells: They remain in restricted regions. They proliferate to form gonads.
They are ectodermal in hydrozoa and endodermal in Scyphozoa and Anthozoa.
(g) Cnidoblasts: Many of the interstitial cells of the epidermis become specialized to
form the stinging cells, called the cnidoblasts. They migrate to the tentacles
through the mesoglea by means of amoeboid movements. Projecting cnidoblasts act as
organs for offence and defence.
(B) Gastrodermis: It is the inner layer of the body. The cells are of following types:
(a) Endothelio-muscle or nutritive muscle cells: They help in contraction of the body
and nutrition.
(b) Endothelio-gland cells: They secrete digestive enzymes in coelenteron. In the region
of hypostome and mouth are found mucous gland cells. Gland cells are absent in the
tentacles and basal disc.
(c) It also contains interstitial cells, sensory cells and nerve cells but no cnidoblasts.
4. Digestion is intra and extracellular. The body of coelenterates enclose a gastrovascular
cavity (coelenteron), having single opening hypostome.
5. Some of the cnidarians possess hard exoskeleton composed of calcium carbonate
(CaCO3).
 The cytoplasm of a cnidoblast contains a
conspicuous nucleus lying to one side, and
a peculiar oval or pyriform sac filled
with a poisonous fluid, hypnotoxin. The
sac is a part of stinging apparatus,
known as the nematocyst (stinging
structure).
 The nematocysts occur scattered mostly
singly, throughout the epidermis of the
body but remain absent on the basal
disc.
 They are abundant in the epidermis of the oral region and the tentacles where they
cluster as wart-like nematocyst batteries.
6. Body forms:
Metagenesis and Polymorphism
 These members shows polymorphism most common is polyp medusa forms.
Polyp 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
Concept Builder

 In the life-cycle there is an alternation of the asexual polyp phase and the sexual
medusa phase and it is termed as Metagenesis.
 During sexual reproduction, medusae liberate gametes into water. Following
fertilization, the zygote forms a ciliated larva called Planula, which swims, settles
and grows into a sessile polyp. (Some cnidarians, like Hydra, do not have a medusa
stage. Hydra has no larval form, no metagenesis).
 Polyps reproduce asexually by budding where as, medusa liberates gametes into
water during 'Sexual reproduction. Both asexual and sexual forms are free living.

CLASSIFICATION
Chiefly on the basis of the dominance of medusoid or polypoid phase in the life
cycle, the phylum Cnidaria is divided into three classes.
Coelenterata is classified into three classes
Hydrozoa Scyphozoa Anthozoa (Actinozoa)
– Fresh water as well as marine
– Polyp medusa often show
polymorphism metagenesis.
– Mesoglea is Acellular
– Gastrovascular cavity undivided.
– Gonads are Ectodermal and shed
gametes directly in to the
surrounding water.
– Cnidoblast is present only in
epidermis
e.g. Hydra - Fresh water polyp
Physalia - the Portuguese man-
of-war. (Neurotoxic, gas gland
present)
– Exclusively marine
– Medusa form is more common
– Mesogloea is thick, gelatinous and
contains cells.
– Gastrovascular cavity undivided.
– Gonads are Endodermal and shed
the gametes into the digestive
tract when escape through the
mouth.
– Cnidoblast is present in epidermis
Gastrodermis
e.g. Aurelia - the Jelly fish, Moon
jally,
Larva - Ephyra
– Exclusively marine
– Only polyp form
– Mesogloea contains cells fibres
– Gastrovascular cavity have
compartment i.e. mesenteries
– Gonads -Endoermal and shed
gametes into the digestive tract
escape via mouth
– Cnidoblast is present in epidermis
Gastrodermis
e.g. This class has two types of animal
(1) Anemones - Skeleton absent
Adamsia - sea anemone
(2) Coral - CaCO3 Skeleton
Pennatula - the sea pen
Gorgonia - the sea fan
4. PHYLUM: CTENOPHORA / SEA WALNUT / COMB JELLIES
These are purely marine, solitary, free swimming
or pelagic, very active animals with transparent
and flat or oval body shape and have following
important characters:
1. Body soft, delicate, transparent and gelatinous
without segmentation.
2. Polyp phase is absent in their life cycle, shape is
typically spherical, pear shaped or cylindrical,
flat in some.
3. They are radially symmetrical, diploblastic, tissue
level of organisation and devoid of cnidoblast
cells.
4. Tentacles may be present or absent. When
present, the number of tentacles is 2. They are
solid and possess adhesive cells called colloblasts
(lasso cells). Digestion is both extracellular and
intracellular. Bioluminescence (the property of a
living organism to emit light) is well-marked in ctenophores.
5. The animals move by cilia, which join together to form comb plates. There are

eight median combplates forming locomotor organs, hence organisms are called
comb-jellies or sea-walnuts.
6. Gastrovascular cavity is branched and opens to the exterior by stomodaeum.
7. They are diploblastic animals but the mesoglea is different from that of cnidaria;
it contains amoebocytes and smooth muscle cells and is comparable to a loose
layer of cells. From this viewpoint, ctenophores may be considered as
triploblastic.
8. Skeletal, circulatory, respiratory and excretory systems are absent. Nervous
system is diffuse type.
9. The presence of a special sense organ 'Statocyst' at the opposite end of the
mouth (aboral end) is the characteristic of the members of this phylum.
10. All are hermaphrodite. Testes and ovary formed side by side from endoderm of
digestive canals.
11. Asexual reproduction doesn't occur. They reproduce only by sexual means.
Fertilization is external. Development is indirect and an immature ciliated stage
called 'cydippid larva' is found in some forms.
Examples: Tentaculata Class: Hormiphora (The sea walnut), Pleurobrachia (The
sea gooseberry), Ctenoplana, Cestum (The venus girdle)
Nuda class : Bereo
Word roots and Origins :
(a) Colloblasts from the Greek kolla meaning glue and blastos meaning bud.
(b) Ctenophore from the Greek ktene meaning comb and phors meaning bearing.
Concept Builder

5. PHYLUM: PLATYHELMINTHES (Flatworms)
 Phylum Platyhelminthes contains about 13,000 species, mostly parasites that live
in other animals including man.
 The important characters of this phylum are:
1. The flat worms are mostly parasites but some are free living
e.g., Planaria.
2. They are acoelomate, triploblastic, bilaterally symmetrical
and dorsoventrally flattened animals.
3. They have organ system level of organisation.
4. Body is not segmented except in class Cestoda (false
segmentation).
5. Body is covered with a cellular, syncytial, one layered, partly
ciliated epidermis; while in parasitic trematodes and
cestodes, epidermis is lacking and the body is covered with
cuticle.
6. Exoskeleton and Endoskeleton are completely absent. However hooks, spines,
suckers (in parasitic form), teeth or thorns may be present which act as adhesive
organs.
7. The space between the body wall, alimentary canal and other organs is filled with
a peculiar connective tissue called the parenchyma. It helps in transportation
of food materials.
8. Digestive system is totally absent in tapeworms, so they absorb food directly
through body surface. In Trematoda and Turbellaria, it consists of mouth,
pharynx and blind intestine (anus absent).
9. Respiratory and circulatory systems are absent.
10. Excretory system consists of single or
paired protonephridium with flame
cells.
11. Nervous system is primitive. The
main nervous system consists of a pair
of cerebral ganglia or brain and one to
three pairs of longitudinal nerve cords
connected to each other by transverse
commissures. This type of nervous
system is called ladder like nervous

system e.g., Planaria (Dugesia).
12. Sense organs are of common occurrence in Turbellaria but these are greatly
reduced in parasitic forms.
13. Sexes are united, i.e., hermaphrodite with very few exceptions like Schistosoma
(Blood fluke).
14. Asexual reproduction by fission occurs in many fresh water forms like
Turbellarians.
15. In majority of forms, eggs are devoid of yolk but provided with special yolk cells
and are covered by egg shell.
16. Cross fertilization in trematodes and turbelleria and self-fertilization in
cestodes is very common. Fertilization is internal. Development indirect with
many larval stages.
17. Life cycle complicated, involves one or more hosts.
18. Regeneration. It is well marked in some flat worms like Planaria.
• Fasciola (Liver Fluke) : Found in bile ducts of liver of sheep goat. Causes Liver rot or
Cirrhosis.
Primary Host: Sheep Goat
Secondary Host: Garden snail (Planorbis ; Limnea ; Bulinus)
Larval stage : Miracidium, Sporocyst, Redia, Cercaria and Metacercaria
Infective stage for primary host : Metacercaria
Infective stafe for secondary host : Miracidium
• Taenia solium: Cause Cysticercosis or Taeniasis
Primary host : Man
Secondary host : Pig
• Larval stage : Onchosphere, Hexacanth,Bladderworm,Cysteicercus.
Infective stage for primary host : Cysticercus
Infective stafe for secondary host : Onchosphere
Concept Builder
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CLASSIFICATION
 Phylum platyhelminthes is 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),
Microstomum, Macrostomum,
Icthyophaga
– 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)
Schistosoma (blood liver fluke)
Paragonimus - Lung fluke worm
– 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). Alimentary
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
Taenia saginata - Beef tapeworm
Echinococcus - Dog tapeworm

6. PHYLUM: NEMATHELMINTHES OR ASCHELMINTHES
 The phylum includes bilaterally symmetrical, triploblastic, pseudocoelomate
animals with organ system grade of organisation. They are circular in cross-
section.
 They are free living, aquatic or terrestrial or parasitic
(on plants or animals).
 They have tube-within tube type of body plan evolved along Protostomic
evolutionary line.
• Body wall consist of
(1) Cuticle - Firm, non living, resistant to digestive enzymes of host.
(2) Epidermis- Without cilia. Syncytial i.e. a continuous layer of cytoplasm having
scattered nuclei.
(3) Muscle layer - Longitudinal.
• Body cavity is there between body wall and digestive tract. Which is not lined by
mesothelium i.e. Pseudocoel (developed from blastocoel) and contain
Pseudocoelomic fluid.
• Skeleton is not mineralized. High fluid pressure in the pseudocoelom maintains
body shape. It is called Hydroskeleton.
• Digestive tract is complete differentiated into mouth, pharynx, intestine Anus.
Mouth is surrounded by 3 - lips.
Pharynx is muscular. It is used to suck food. Intestine is non muscular.
• 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 involves an excretory cell (a large giant H-shaped cell) called

Renette cell (multinucleated).
 Sexes separate, show sexual dimorphism, fertilisation internal, development
direct or indirect.
CLASSIFICATION- On the basis of caudal receptor or phasmids, Aschelminthes can
be divided into 2 classes-
Aschelminthes
Aphasmidia Phasmidia
Class
Class–Aphasmidia
(i) Members of this class lack phasmid.
(ii) Many types of amphids are found.
(iii) One pairs of excretory canal are present.
(iv) Caudal adhesive glands are found.
Ex. Desmoscolex
Class–Phasmidia
(i) Phasmid is present.
(ii) Caudal adhesive glands are not
found.
Ex. : Ascaris, Entrobious,
Wuchereria

7. PHYLUM: ANNELIDA
 The phylum includes over 9,000 species of metamerically segmented animals
with a true coelom called the Schizocoelom.
• First Protostomous eucoelomate animals.
General characters of Phylum Annelida
1. The organisms are triploblastic, bilaterally symmetrical, coelomates with organ
system level of body organization and are metamerically segmented.
2. Body wall has an epidermis of columnar epithelium coated
externally by moist albuminous cuticle and with circular
and longitudinal muscle fibres.
3. Chitinous setae, aiding in locomotion, may or may not be
present on fleshy parapodia; absent in leech.
4. Annelids are the first animals to have a true schizocoelic
coelom. Coelom is divided by septa into compartments.
5. The coelomic fluid act as a hydrostatic skeleton.
6. Digestive system is complete and digestion is extracellular.
7. Respiration by moist skin (cutaneous respiration) or
through gills (Branchial respiration).
8. Blood vascular system is usually closed. Respiratory
pigments, either haemoglobin or erythrocruorin, are
dissolved in blood plasma. Free amoeboid blood corpuscles are present, but there
are no RBCs. In leech, there is no true blood vascular system.
9. Nephridia are the excretory organs. Ammonia is chief excretory waste.
10. The nervous system consists of a nerve ring and a solid, double, mid-ventral nerve
cord with ganglia and lateral nerves in each segment.

11. Sensory organs include tactile organs, taste buds, statocysts, photoreceptor cells
and eyes with lenses.
12. The sexes may be separate (e.g., Nereis) or united (e.g., earthworm, leech).
13. Development is mostly direct (e.g., Earthworm). There is indirect development in
Nereis. Larva, when present is trochophore.
CLASSIFICATION OF ANNELIDA
Based on presence or absence/of Parapodia, Setae and Sense organs
Polychaeta Oligochaeta Hirudinea Archiannelida
1. Almost all are marine
2. Cephalisation is more
distinct.
3. Setae numerous
4. Clitellum absent
e.g.
Nereis – Sand worm/
clamworm
1. Most of the members
are terrestrial, but
some are aquatic.
2. Cephalisation absent.
3. Number of seatae is
limited
4. Clitellum is present
e.g.
Pheretima
1. Aquatic, terrestrial,
ectoparasite and
sanguivorous.
3. Parapodia and seatae
are absent.
4. Clitellum develop only
in breeding season.
e.g.
Hirudinaria –
Fresh water leech
1. All Marine
3. Parapodia and seatae are
absent.
4. Clitellum absent.
e.gPolygordius –Connecting-link
between Annelida Mollusca
(living fossil) Larva known as
Loven's Larva

NEREIS
Inhabits in sea - shore between tide mark, burrower, nocturnal,
carnivorous, gregarious, fertilization - in sea.
Parapodia in each segment except first last. During breeding
body divides in two parts. Anterior asexual part - Atoke and
posterior sexual portion Epitoke. This change is known as epitoky.
8. PHYLUM. ARTHROPODA
 It is the largest phylum in the animal kingdom, including 900,000 species. The
largest class is insecta with 750,000 species.
 General chacters are:
1. They are triploblastic, coelomate bilaterally symmetrical animals. Body cavity is full of
haemolymph (blood) it's known as haemocoel. The true coelom is restricted to gonads.
2. The body is covered by chitinous cuticle, which forms the exoskeleton which is shed at
intervals i.e., undergo moulting/ecdysis.
3. They have a segmented body, each
segment bearing a pair of jointed
appendages covered by a jointed
exoskeleton. Chitinous exoskeleton is secreted by the underlying epidermis.
Concept Builder
MILLIPEDE HONEYBEE DRAGON FLY

4. 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.
5. Respiration is through body surface or special structure such as gills (e.g. Prawn),
Trachea (e.g Insects), Book-lungs (e.g. Scorpion), Book-gills (e.g. King crabs). Trachea
carry oxygen direct to the cells.
6. Excretion takes place through green glands or malpighian tubules since nephridia are
absent.
7. Sensory structures in arthropods are antennae for perceiving odour, eyes, statocysts or
balance organs and sound receptors (in chirping crickets and cicadas). Eyes are simple or
compound. In honey bees, butterflies, moths and some other insects, the gustatory
receptors are present on their feet.
8. The heart is dorsal and circulatory system is open.
9. The central nervous system consists of paired pre-oral ganglia connected by
commissures to a solid double ventral nerve cord.
10. In land arthropods, the fertilization is always internal.
11. Arthropods are mostly dioecious, oviparous. In some like the scorpion, the eggs
hatch within the female body. They bring forth the young ones alive. They are
viviparous. Development is direct or indirect.

Advancement Over Annelida
1. Distinct-head in all species.
2. Jointed appendages serving a variety of functions.
3. Jointed exoskeleton for protection and muscle attachment.
4. Striped muscles arranged in bundles for moving particular body parts.
5. Special respiratory organs such as gills, trachea, book lungs in majority of cases.
6. Well developed sense organs such as compound eyes, statocysts, auditory organs, taste
receptors etc.
7. Endocrine glands and pheromone secretion for communication.
1. Peripatus is considered as connecting link between annelida and arthropoda as it has unjointed legs and
breathes by trachea.
2.Larvae of different Arthropods
(a) Bombyx(Silkworm) 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
3.Terga are dorsal plates whereas sterna are ventral plates of exoskeleton.
4.Arthrodial membranes join the different sclerites.
5.Halters are drumstick shaped, second pair of reduced wings of housefly and mosquito which helps
in balancing.
6.Eggs of Culex are cigar shaped; they are laid vertically on the surface of water in clusters; airfloats
are absent; whereas in Anopheles eggs are boat shaped, laid singly and horizontally; they have
airfloat.
7.Larva of Culex is bottom feeder whereas larva of Anopheles is surface feeder.
8.Adult of Culex lies parallel to the surface and both ends of body deflexed whereas in Anopheles, the
body is inclined at an angle of 45° to the surface. So, they can be distinguished with the help of
sitting posture.
9.In Spider, Spinnerets are present anterior to the terminal anus. They produce silken thread.
10. Von Frisch described the process of communication of food source in honey bees.
11. Insecticides sprayed over the mosquitoes desensitize their nervous system as well as
chemoreceptors and mechanoreceptors of the antennae.
12. Johnston's organs are present on antennae of mosquitoes.
13. The life cycle is generally accompanied with metamorphosis. Larvae and adults may show different
feeding habits and occupy different habitats.
14. Insects like bees, wasps, beetles, moths and butterflies are good pollinators for important crops.
15. Ants, termites and locusts are eaten by Chinese and Indians; Eggs of aquatic bugs are used as
food by Mexicans; Ox-warbles are eaten by Red Indians.
16. Dragon flies feed on the larvae of mosquitoes
17. Glow worm (Firefly) shows bioluminescence.
18. Adult Culex and Anopheles can be distinguished with the help of Sitting posture.
19. The insects may be divided into five groups on the basis of their mode of development.
1. Ametabola insects – metamorphosis absent. The young ones resemble adult.
Eggs ⎯→
⎯ Young ⎯→
⎯ Adult
ex. Lepisma (Silver fish)
2. Paurometabola insects – gradual metamorphosis
Eggs ⎯→
⎯ Nymph ⎯→
⎯ Adult
Concept Builder

ex. Cockroach, Grasshopper, Locusts etc.
3. Hemimetabola insects – incomplete metamorphosis. Habitat of young ones is different from
adults.
Eggs ⎯→
⎯ Naiads ⎯→
⎯ Adult
ex. Dragon flies (Naiads aquatic but adults aerial)
4. Holometabola insects – complete metamorphosis
Eggs ⎯→
⎯ Larva ⎯→
⎯ Pupa ⎯→
⎯ Adult
ex. House flies, Butterflies, Mosquitoes etc.
5. Hypermetabola insects – various forms of larvae
Eggs ⎯→
⎯ Larva(1) ⎯→
⎯ Larva(2) ⎯→
⎯ — ⎯→
⎯ Pupa ⎯→
⎯ Adult
ex. Blister beetle.
9. PHYLUM – MOLLUSCA
Phylum mollusca is the second largest phylum in animal kingdom which includes over
60,000 species. General characters are :
 Molluscs are terrestrial, aquatic (fresh water or marine) triploblastic, bilaterally
symmetrical, schizocoelic and unsegmented animals.
 Most molluscs secrete a shell of calcium carbonate that protects and supports
their soft tissues.

 The body is organised into three general regions: head, foot and visceral hump.
 The visceral hump contains the digestive tract and other visceral organs.
 The body is covered by a soft and spongy skin fold called mantle which
secretes the shell.
 The space between the hump and the mantle is called mantle cavity in which
feather like gills are present.
 Molluscs typically employ a feeding organ called radula which is armed with
rows of chitinous teeth. The radula is protruded from the mouth and worked
back and forth to rasp the food into fine particles.
 Circulatory system is mainly of open type but some reduced sinuses are present.
Respiratory pigment is haemocyanin.
 Respiration occurs by feather like gills, pulmonary sac or both, or through
general body surface.
 Excretion occurs by paired Organ of Bojanus. Another excretory organ called
Keber's organ (Pericardial gland) is also present in Unio along with paired organ
of Bojanus. It pours the waste into pericardium from where the waste is carried
to the organ of Bojanus that opens out through mantle cavity.
 Sense organs include eyes, statocysts and osphradia (chemoreceptor to test
chemical nature of water).
 Reproduction sexual, adults can be dioecious
(unisexual) or monoecious (bisexual or
hermaphrodite) Fertilization is generally
external, development is direct or through
free larval forms like trochophore, veliger
(in Pila), glochidium (in Unio) -an
ectoparasite on fishes.
CLASSIFICATION
Molluscs' classification is mainly on the basis of shell and foot.
Cephalopoda
-
Marine
Body
-
Bilateral
head

foot
combined
cephalopoda
Shell-Internal
and
reduced
it
may
be
external
(Nautilus)
or
absent
(Octopus)
Radula
-
Present
Foot
-
Modified
into
a
funnel
and
partly
into
8
or
10
sucker
bearing
arms
that
surround
the
mouth
Locomotion
is
by
expelling
water
in
jet
through
siphon
(Jet
propulsion).
Ink
glands
in
some
squids
for
offense
and
defense.
When
the
squid
is
attacked,
it
emits
a
cloud
of
inky
fluid
through
its
siphon.
This
'smoke
screen'
interferes
with
the
vision
and
chemoreceptors
of
the
predator
and
thereby
helps
the
squid
to
escape.
-
Closed
blood
circulation.
-
Hectocotyle
for
Pelecypoda
Bivalvia
or
Lamellibranchiata
-
Marine/fresh
water
Body-Bilateral
and
flat
Head-Absent
Shell-Consist
of
two
valves
Movably
hinged
dorsally.
Radula-Absent
Foot-Plough
or
Wedge
shaped
for
burrowing
Larva-Glochidium,
Trochophore
e.g.
Unio-Mussel
(fresh
water)
Pinctada-Pearl
oysters.

Gastropoda
-
Marine/fresh
water
/moist
soil.
largest
class.
Body-Symmetrical
embryo
grows
into
an
asymmetrical
adult
due
to
twisting/torsion
of
visceral
mass
during
development.
mouth

anus
lie
on
same
side.
Head-With
eyes

tentacles.
Shell
-
Spirally
coiled
Radula
–
Present
Foot
-
Large

flat
Larva
-
Trochophore
or
Veliger.
e.g.
Pila-Apple-snail
(Shell
used
in
but-
tons)
Scaphopoda
-
Marine
Body
-
Bilateral
Head
-
absent.
Shell-Tubular,
open
at
both
end.
Radula-Present
Foot
-
Conical
and
use
for
digging
Larva
-
Trochophore
e.g.
Dentalium-Tusk-shell.
(Respire
by
mantle)
Polyplacophora/
Amphineura
-
Marine
Body
-
Bilateral
Head
-
reduced
without
eyes
and
tentacles.
Shell
-
Present
or
absent.
8
dorsal
plates
present.
(Multivalved)
Radula
–
Present
Foot
-
Reduced/absent.
Larva-Trochophore
e.g.
Chiton-The
coat
of
mail
shell
(Sea-mica)
Chaetopleura-
Aplacophora
-
Marine,
Worm
like
Body-Small
covered
by
thick
mantle
Head-Small
without
eyes

tentacles
Shell
-
Absent.
Radula
-
Present
Foot-
Reduce/absent.
Larva-Trochophore
e.g.
Neomenia
Monoplacophora
-
Marine,
common
character
of
Annelida
and
Arthropoda.
Body
-
Bilaterally
symmetrical
and
segmented.
Head
-
Indistinct
Shell
-
Dome-shaped
with
mantle.
Radula
-
Present
Foot
-
Flat
muscular
Larva
-
Trochophore
e.g.
-
Neopilina
Living
fossils
Connecting
link
of
Annelida
and
Mollusca
and
only
segmented
molluscs
with
nephridia.
(i) Architeuthis (Giant AtJantic squid) is the largest and heaviest among
invertebrates, 55 feet length.
(ii) Nautilus is the only cephalopod with external shell, so ink glands are absent.
(iii) The colour change in cephalopods occurs due to chromatophores.
Concept Builder

10. PHYLUM: ECHINODERMATA
 They are exclusively present in marine water and there are no parasitic
forms. Similarities with chordates:
(i) They have tube within tube type of body plan which has evolved along
deuterostomic evolutionary line.
(ii) They possess a true coelom called enterocoelom.
(iii) They have mesodermal skeleton made of calcareous plates or ossicles.
 All these characters make the echinoderms closer to chordates. The other
characters are:
1. The symmetry is bilateral in larvae but pentamerous radial in adults.
2. Many echinoderms bear a number of calcareous spines on their body surfaces
called tubercles. Between the spines, there are pincer like structures called
pedicellariae to keep the surface clean. Pedicellariae are made of three
calcareous plates. Two calcareous valve like structures in the form of jaws
resting upon a basal calcareous plate.
3. Between the spines, there are finger like processes called dermal branchiae
which help in respiration.
4. Mouth is on ventral/oral side and aniss is on dorsal or aboral side.
5. There is no distinct anterior and posterior end i.e., no cephalisation.
6. Haemal and Perihaemal Systems: Instead of blood vascular system, there are
present haemal and perihaemal systems which are of coelomic origin. Thus the so
called circulatory system is open type. The so called blood is often without a
respiratory pigment. There is no heart.
7. Respiratory Organs: Gaseous exchange occurs by dermal branchiae or papulae
in star fishes, peristominal gills in sea urchins, genital bursae in brittle stars
and cloacal respiratory trees in holothurians. Exchange of gases also takes place
through tube feet.
8. Excretory organs: Specialized excretory organs are absent. Nitrogenous wastes

are diffused out via gills or dermal branchiae. Ammonia is chief excretory
matter.
9. Sexes are separate. Reproduction is sexual. Fertilization is usually external.
Development is indirect with free-swimming larva.
A unique water filled ambulacral or water vascular system with tube feet to help in locomotion.
Capture and transport of food and respiration. A perforated plate madreporite permits entry of
water into ambulacral system which also help in capturing food and gas transport system.
Structures like Pollian vesicle, tiedmann body or recemose, stone canal are also found in water
vascular system.
Divided
into
Five
classes
Crinoidea
Body
form
-
Plant
like
fixed
with
cirri.
Arms
-
Highly
branched
Spines
-
Absent
Pedicellariae
-
Absent
Ambulacral
groove
-
Oral
and
ciliated
Madreporite
-
Absent
Anus
–
Oral
Viscera
-
Extend
upto
arms
Respiration
-
Tube
feet
Suckers
–
Absent
Larva
-
Doliolaria
Antedon
-
Sea
lilly
(most
primitive)
Holothuroidea
Body
form-Long

cylindrical
Arms
-
Absent
Spines
Absent
Padicellariae
-
Absent
Ambulacral
groove
–
Absent
Madreporite
-
Internal
Anus
–
Aboral
Viscera
-
No
Viscera
into
arms.
Respiration-
Cloacal
tree
Suckers
–
Present
Larva
-
Auricularia
Cucumaria
-
Sea
Cucumber
Echinoidea
Body
form
-
Globular/disc
like.
Arms
-
Absent
Spines
-
Present
Pedicellariae
-
Present
Ambulacral
groove
–
Absent
Madreporite
-
Aboral
Anus
–
Aboral
Viscera
-
No
Viscera
into
arms.
Respiration
-
Peristomium
gills
Suckers
–
Present
Larva
-
Pluteus
Mouth
-
with
biting

chewing
tooth
apparatus
Aristotle's
lantern
(Masticating
apparatus
with
5
teeth)
Echinus-sea
urchin
Concept Builder

Ophiuroidea
Body
form
-
Flat

star
like
Arms
-
Five
or
multiple
of
five.
Sharply
marked
with
the
central
disc
Spines
-
Present
Pedicellariae
-
Absent
Ambulacral
groove
-
Not
visible
Madreporite
-
Oral
Anus
-
Absent
Viscera
-
No
Viscera
into
arms.
Respiration
-
Genital
bursae
Suckers
–
Absent
Larva
-
Ophiopluteus
Ophiura
(Brittle
star)
1. The starfish uses the suction cup-like ends of the tube feet of one arm to hold on to
rocks, as it moves the other arms. It can open bivalves (molluscs) by attaching two arms
to either sides of a bivalve and pulling them apart. The bivalve opens out, the stomach of
starfish is then everted through its mouth and introduced into the open mollusc which is
partly digested before being ingested. Echinoderms predate on coral polyps also.
2. Word roots and origin : ampulla from Latin meaning ''flask''.
10. PHYLUM: HEMICHORDATA / STOMOCHORDATA
 Hemichordata was earlier considered as a sub-phylum under chordata. But now it
is placed as a separate phylum under non-chordata.
 The phylum consists of a small group of worms like
marine animals with organ system level of
organisation.
 Its characteristics are :
(i) True notochord is absent. gill slits are present but
they are dorso lateral in position. They are worm
like. bilaterally symmetrical. triploblastic and
entero-coelomate animals.
(ii) Stomochord is a hollow outgrowth arising from the
roof of the buccal cavity, also called 'buccal
diverticulum'. It is present in the proboscis.
(iii) Dorsal heart, ventral hollow nerve cord, no
respiratory pigments. Circulatory system is open.
Respiration by gills.
(iv) Development is mostly indirect through a free swimming tornaria larva. e.g.
Balanoglossus (acorn, tongue worm), Glossobalanus. Sexes are separate.
Concept Builder

Fertilization is external.
(v) Believed to be connecting link between non-chordates and chordates.
(vi) Due to the absence of true notochord in hemichordata, many taxonomists do not
consider these animals as chordates.
(vii) Excretory organ is proboscis gland.
(viii) The body is cylindrical and is composed of an anterior proboscis, a collar and a
long trunk.
Examples : Balanoglossus, Saccoglossus
SUMMARY
1. The basic fundamental features such as level of organisation, symmetry, cell
organisation, coelom, segmentation, notochord, etc., have enabled us to broadly
classify the animal kingdom. Besides the fundamental features, there are many
other distinctive characters which are specific for each phyla or class.
2. Porifera includes multicellular animals which exhibit cellular level of organisation
and have characteristic flagellated choanocytes. Ostia present all over the body,
with a Single opening osculum on top. Sponges have a characteristic canal system.
They are hermaphrodite. Skeleton made up of calcareous or siliceous spicules or
spongin fibres.
3. Coelenterates have tentacles and bear Cnidoblasts. They are mostly aquatic,
sessile or freefloating. They show radial symmetry, are acoelomate, diploblastic
with gastrovascular cavity. Some cnidarians show metagenesis.
4. Ctenophores are exclusively marine, diploblastic acoelomate with radial
symmetry. They lack cnidoblasts have colloblasts. Locomotion by comb plates.
5. Platyhelminthes are first triploblastic animals. They are acoelomate, with
bitateral symmetry and blind sac body plan. They are generally hermaphrodite.
They are mostly parasites and show distinct suckers and hooks for attachment.
6. Aschelminthes are triploblastic, unsegmented and show bilateral symmetry. They
are pseudocoelomate with complete alimentary canal. They are generally
dioecious.
7. Annelids are first to acquire metameric segmentation and true coelom. Body
bears appendages for locomotion in the form of chitinous setae or parapodia.
8. Arthropods are the most abundant group of animals characterised by the
presence of jointed appandages. They are triploblastic, coelomates with
metamerically segmented body and open circulatory system. Exoskeleton is
Chitinous.
9. Molluscs, they have soft unsegmented body covered by a hard calcareous shell
secreted by a fold of skin mantle covering the visceral mass.

10. Echinoderms are exclusively marine and possess spiny skin. Their most distinctive
feature is the presence of water vascular system. Larva has bilateral symmetry
but the adult has radial symmetry.
11. The Hemichordates are small group of worm like marine animals. They have a
cylindn'cal body with proboscis, collar and trunk.
EXERCISE – 1
Section – A
Q.1 Sponges in which the calls are loosely aggregated and do not form tissues or organs are
grouped under which sub-kingdom?
(1) Metazoa (2) Eumetazoa (3) Parazoa (4) Bilateria
Q.2 Level of organization in coelentrates is
(1) Acellular (2) Cellular (3) Tissue (4) Organ system
Q.3 Blind sac body plan is found in
(1) Sponges (2) Annelids (3) Coelentrates (4) Round wonns
Q.4 Annelids possess
(1) Cell aggregate plan (2) Blind sac plan
(3) Tube within a tube plan (4) Hollow sac plan
Q.5 'Tube within a tube' plan is not exhibited by one of the following phyla
(1) Coelenterata (3) Annelida (2) Aschelminthes (4) Arthropoda
Q.6 An animal having triploblastic acoelomic condition is
(1) Ascaris (2) Periplaneta (3) Planaria (4) Sycon
Q.7 Animals which are triploblastic with tube within tube type of body plan and embryonic
blastopore forms anus (deuterostomia) are
(1) Annelids (2) Molluscs (3) Platyhelminthes (4) Echinoderms
Q.8 Echinoderms and chordates have
(1) Pseudocoel (2) Shizocoelom (3) Enterocoelom (4) Haemocoel
Q.9 Body cavity of arthropods is called
(1) Coelom (2) Haemocoel (3) Pseudocoel (4) Gastrovascular cavity
Q.10 A deuterostomic animal is
(1) Star fish (2) Sea Anemone (3) Pearl oyster (4) Octopus
Q.11 True segmentation (metameric) occurred for the first time in
(1) Platyhelminthes (2) Aschelminthes (3) Annelids (4) Arthropods
Q.12 Animals possessing pseudocoelom are
(1) Flatworms (2) Round worms (3) Annelids (4) Molluscs
Q.13 True coelom appeared fjrst in the course of evolution in
(1) Echinodermata (2) Annelida (3) Chordata (4) Aschelminthes
Q.14 Biradial symmetry is found in
(1) Obelia (2) Sea Anemone (3) Hydra (4) Aurelia
Q.15 Which is the only phylum in the animal kingdom without any nerve cell?
(1) Porifera (2) Coelenterata (3) Annelida (4) Eumelazoa
Q.16 The basis of classification of protozoa is
(1) Mode of nutrition (2) Mode of reproduction
(3) Mode of locomotion (4) Mode of respiration
Q.17 Dum-dum fever is caused by
(1) Leishmania donovan (2) Glossina palpalis

(3) Giardia intestinalis (4) Trypanosoma gambiens
Q.18 The relationship between Lophomonas and wood cockroach is of
(1) Parasitism (2) Commensalism (3) Symbiosis (4) Ammensalism
Q.19 Oriental sore disease in man is caused by which one of the following?
(1) Leishmania tropica (2) L. donovani
(3) L. brasiliensis (4) Phlebotomus intermedius
Q.20 Trypanosoma gambiense causes
(1) Sleeping sickness (2) Yellow fever (3) Kala-azar (4) Oriental sore
Q.21 The vector of Trypanosoma gambiense is
(1) Sand fly (2) Fruit fly (3) Tse-Tse fly (4) House fly
Q.22 A sarcodine causing dysentry is
(1) Giardia (2) Entamoeba (3) Amoeba (4) Tryponosoma
Q.23 Silica shells mayor may not occur in one of the following
(1) Amoeboids (2) Heliozoans (3) Radiolarians (4) Foraminiferans
Q.24 Time period from the initial infection to first appearence of symptoms is known as
(1) Pre-patent period (2) Incubation period
(3) Pre-erythrocytic period (4) Exo-erythrocytic period
Q.25 Tetranucleated cyst stage Is found in
(1) Entamoeba coli (2) Entamoeba histolytica
(3) Leishmania (4) Trypanosoma
Q.26 Which of the following organisms is known to form abscesses in human liver, lungs, brain
etc.?
(1) Entamoeba histolytica (2) Monocystis
(3) Plasmodium (4) Fasciola hepatica
Q.27 Which one of the following constitutes the reserve food material in the cyst of Entamoeba
histolytica?
(1) Volutin granules (2) Starch granules
(3) Glycogen granules (4) Fat droplets
Q.28 Slipper animalcule is the name of
(1) Pelomyxa (2) Actinophrys (3) Euglena (4) Paramecium
Q.29 Organelle concerned with offence and defence in Paramecium is
(1) Tnchocyst (2) Radial canals (3) Kappa particles (4) Peristome
Q.30 Conjugation in Paramecium is by
(1) Exchange of micronucleus (2) Exchange of macronucleus
(3) Exchange of + and – nuclei (4) Exchange of nuclei
Q.31 The function of cytopyge in Paramecium is to
(1) Fitter food particles
(2) Form the bolus of the food malerial
(3) Segregate debris from useful food material
(4) Egest the indigestible waste
Q.32 Contractile vacuoles of Paramecium are analogous to
(1) Sweat glands of mammals (2) Uriniferous tubules
(3) Gastrovascular cavity of Hydra (4) Typhlosole of Earthworm
Q.33 Removal of micronucleus in Paramecium witt impair the function of
(1) Reproduction (2) Excretion (3) Osmoregulation (4) Locomotion
Q.34 Locomotion in sporozoans occur by
(1) Flagella (2) Cilia (3) Pseudopodia (4) Wriggling movement
Q.35 The most important characteristic of phylum porifera is
(1) They are acellular

(2) They possess blind sac type of body plan
(3) They possess canal system and choanocytes
(4) They possess water vascular system
Q.36 Most of the sponges are marine and remain attached to rocks (sessile). The fresh water
sponge is
(1) Sycon (2) Spongilla (3) Cliona (4) Euplectella
Q.37 Path of water in a sponge is
(1) Dermal ostia → gastral ostia → osculum
(2) Dermal ostia → gastral ostia → spongocoel → osculum
(3) Osculum → spongocoel → choanocytes → ostia
(4) Pinacocytes → choanocytes → enteron → osculum
Q.38 The movement of water in syconoid type of canal system is
(1) Dermal ostia → canal → spongocoel → osculum
(2) Dermal ostia → incurrent canal Prosopyle
⎯⎯⎯⎯
→ radial canal Apopyle
⎯⎯⎯⎯
→ spongocoel →
osculum
(3) Dermal ostia → incurrent canal Prosopyle
⎯⎯⎯⎯
→ flagellated chamber Apopyle
⎯⎯⎯⎯
→ excurrent
canal → spongocoel → osculum
(4) Pinacocytes → choanocytes → enteron → osculum
Q.39 Which one of the following cells are totipotent and are responsible for regenerative capacity
in sponges?
(1) Pinacocytes (2) Thesocytes (3) Archaeocytes (4) Scleroblast
Q.40 The skeleton of bath sponge, Euspongia, is made of
(1) Spongin fibres (2) Siliceous spicules
(3) Calcareous spicules (4) Spongin fibres and siliceous spicules
Q.41 A sponge harmful to oyster industry is
(1) Spongilla (2) Euspongia (3) Hyalonema (4) Cliona
Q.42 Which of the following lives in commensal relationship with Shrimps and is called as 'Venus
Flower Basket'?
(1) Leucosolenia (2) Euplectella (3) Euspongia (4) Sycon
Q.43 Larva of Leucosolenia is
(1) Parenchymula (2) Amphiblastula (3) Planula (4) Trochophore
Q.44 Mode of digestion in sponges is
(1) Intracellular (2) Intercellular
(3) Intracellular and Intercellular (4) None of these
Q.45 The spongocoel of sponges is homologous to the
(1) True coelom of earthworm (2) Haemocoel of cockroach
(3) Pseudocoelom of Ascaris (4) None of these
Q.46 In the absence of a closed vascular system, how do sponges manage to distribute the
nutritive substances from choanocytes to rest of the cells?
(1) Through cell to cell diffussion
(2) Through mesoglea which acts as the food reservoir and distribution system
(3) Through the wandering cells, amoebocytes
(4) Through cell to cell diffusion and amoebocytes
Q.47 Hydra and Obelia are
(1) Diploblastic, blind sac body plan, radial symmetry, acoelomate
(2) Diploblastic, bilaterally symmetrical and acoelomate
(3) Triploblastic , radially symmetrical and coelomate
(4) Triploblastic, bilaterally symmetrical and coelomate

Q.48 The most important characteristic of phylum Cnidaria is
(1) Cnidoblasts (2) Choanocytes (3) Thesocytes (4) Archaeocytes
Q.49 Digestion in Hydra is
(1) Extracellular (2) Intracellular
(3) Extracellular and intracellular (4) Holozoic
Q.50 Metagenesis is found in
(1) Physalia (Portuguese man of war) (2) Hydra
(3) Obelia (4) Both (1) (3)
Q.51 Which of the following statement is incorrect about metagenesis?
(1) Alternation of asexual and sexual phases in the life cycle of Obelia is called metagenesis
(2) Metagenesis is similar to alternation of generations as found in plants
(3) Both the medusa and polyp are diploid
(4) Medusa is the sexual phase and polyp is the asexual phase
Q.52 Jelly fish belongs to class
(1) Hydrozoa (2) Scyphozoa (3) Anthozoa (4) None of these
Q.53 Sea anemone belongs to
(1) Anthozoa (2) Hydraozoa (3) Scyphozoa (4) Coelenterata
Q.54 Which one of the following is coelenterate?
(1) Sea pen (2) Sea horse (3) Sea urchin (4) Sea cucumber
Q.55 Tick mark the incorrect match
(1) Obelia Planula larva (2) Aurelia Ephyra larva
(3) Nereis Trochophore (4) Hydra Hydrula larva
Q.56 The hypnotoxin is produced by
(1) Penetrant (2) Volvent (3) Large glutinant (4) Small glutinant
Q.57 During discharge of nematocyst the function of lasso is to
(1) Press and squeeze out the thread tube
(2) Trigger the stimulus
(3) Prevent the detachment of nematocyst from nematoblast
(4) None of these
Q.58 A piece of Hydra will regenerate into a full Hydra if it contains a part of
(1) Epidermis
(2) Epidermis, gastrodermis and interstitial cells
(3) Basal disc
(4) Epidermis, gastrodermis and tentacles
Q.59 Which one of the following (cell types) contains the symbiotic Zoochlorellae in Hydra?
(1) Epithelio muscular cells of epidermis
(2) Endothelio muscular cells of gastrodermis
(3) Interstitial cells
(4) Algae embedded in the mesoglea
Q.60 If the body stalk of Hydra is cut transversely into several segments, then in these fragments,
tentacles would regenerate
(1) At the end that was close to the hypostome
(2) At the end that was cl'ose to the basal disc
(3) Randomly at either ends of the cut segments
(4) In none of the segments
Q.61 Main function of interstitial cells is
(1) Replacement of lost cells (2) Excretion
(3) Digestion (4) Defence
Q.62 Organ pipe coral is

(1) Tubipora (2) Gorgonia (3) Pennatula (4) Meandrina
Q.63 Which animal has been placed in wrong habitat?
(1) Hydra vulgaris -sea water (2) Hydra gangetica -fresh water
(3) Obelia -sea water (4) Physalia -sea water
Q.64 Which of the following belong to phylum ctenophora?
(1) Hormiphora (2) Cestum (3) Beroe (4) All of these
Q.65 Which of the following are triploblastic, acoelomate with blind sac type of body plan and
parenchyma cells originating from mesoderm fill up the cavities of the body?
(1) Cnidarians (2) Platyhelminthes (3) Annelids (4) Arthropoda
Q.66 In platyhelminthes, the excretory organs are
(1) Nephridia (2) Nephrons (3) Flame cells (4) Archeocytes
Q.67 Tapeworm is placed in a class
(1) Cestoda (2) Trematoda (3) Sporozoa (4) Turbellaria
Q.68 Which one of the following stages in the life history of liver fluke infects the sheep?
(1) Miracidium (2) Redia (3) Cercaria (4) Metacercaria
Q.69 The correct sequence of various larvae in liver fluke is
(1) Miracidium, sporocyst, cercaria, redia, metacercaria
(2) Miracidium, sporocyst, redia, cercaria, metacercaria
(3) Sporocyst, redia, miracidium, cercaria, metacercaria
(4) Cercaria, sporocyst, redia, miracidium, metacercaria
Q.70 Branched uterus containing fertilized capsules can be seen in tapeworm in
(1) Immature proglottid (2) Mature proglottid
(3) Gravid proglottid (4) Immediately below neck
Q.71 The mature proglottids having fertilized eggs in uterus of tapeworm are regularly detached.
This process is known as
(1) Apolysis (2) Proliferation (3) Strobilation (4) Topolysis
Q.72 Taenia saginata differs from Taenia solium in
(1) Absence of scolex hooks
(2) Scolex devoid of hooks and difference in secondary host
(3) Absence of scolex hooks and presence of both male and female reproductive organs
(4) Presence of scolex hooks
Q.73 Fluke occuring in human beings is
(1) Fasciolopsis (2) Fasciola (3) Dugesis (4) Male Ascaris
Q.74 Schistosoma is known as
(1) Blood fluke (2) Chinese liver fluke
(3) Dog tapeworm (4) Lung fluke
Q.75 Ladder like nervous system, with ventral nerve chord is present in
(1) Cnidaria (2) Platyhelminthes (3) Annelida (4) Arthropoda
Q.76 The larva of Taenia solium is
(1) Cysticercus (2) Megascolex (3) Planula (4) Ephyra
Q.77 Alimentary canal is absent in
(1) Planaria (2) Tapeworm (3) Blood fluke (4) Liver fluke
Q.78 Male Ascaris differs from female in having
(1) Lips (2) Amphids (3) Pineal spicules (4) Tail
Q.79 The epidermis of Ascaris is
(1) Multicellular (2) Syncytial (3) Columnar (4) Cuboidal
Q.80 A free living roundworm is
(1) Enterobius (2) Rhabditis (3) Dracunculus (4) Trichinella
Q.81 The commonest worm in children is

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