Kingdom Animalia 11th std

Kingdom Animalia
Biren Daftary
8/24/2016 BIREN DAFTARY

Introduction
• Animals classified into chordates & non-chordates
• Chordates have a ‘notochord’
• Non-chordates do not have a ‘notochord’
• Notochord is a rod like structure made up of tightly packed vacuolated
cells which run along the mid dorsal line
• Animals showing a vertebral column are called vertebrates
• Animals not having a vertebral column are called as invertebrates
• There are 1.2 million species which show a great diversity of life

CRITERIA FOR ANIMAL CLASSIFICATION

1. Number of germ layers
• Every multicellular organism begins life as a single cell called ‘zygote’
• The zygote divides many times to form a mass of cells
• These mass of cells get arranged into 2-3 layers called as germinal layers
• Diploblastic animal: 2 layers, outer ectoderm & inner endoderm separated
by mesoglea. Example: phylum Cnidaria
• Triploblastic animal: 3 layers, outer ectoderm, middle mesoderm & inner
endoderm. Example: phylum Platyhelminthes onwards

Mesoglea

2. Animal body plan
1. Cell aggregate plan:
• Includes simplest of animal types like sponges
• Animal is made up of aggregation or collection of cells
• Tissues & organs are absent
• There is no nervous co-ordination
• Example: Phylum Porifera
2. Blind sac body plan:
• Shown by slightly complex animals
• Digestive system having a single opening which acts as mouth &
anus. Hence ingestion & egestion is done through that opening
• Example: Phylum Cnidaria

3. Tube within tube body plan:
• Shown by advanced & evolved animals
• Complete digestive system with 2 separate openings for mouth &
anus
• Example: Phylum Annelida onwards

3. Body symmetry
• Symmetry means similarity in shape, size & number of parts on opposite
sides of a median line
• Median line is the plane through which animal can be cut into 2 equal
halves
1. Asymmetrical animals:
• Animals whose body cannot be divided into 2 equal parts through any
plane.
• Example: Some sponges & snails
2. Radially symmetrical animals:
• Animal whose body can be cut into 2 similar halves in many planes
• All the cuts pass through the centre & appear like radii.
• Example: Hydra, starfish, sea anemone

3. Bilaterally symmetrical animals:
• The animal can be divided into 2 equal halves by one 1 single
median plane
• Example: Fish, frog, goat

4. Body cavity or Coelom
• Body cavity is the space between the body wall & the alimentary canal
which is produced by the splitting of the mesoderm during embryonic
development
1. Acoelomates:
• Animals which do not have any body cavity
• The space between body wall & alimentary canal is filled with parenchyma
• Example: Phylum Platyhelminthes
2. Pseudocoelomates:
• These animals show a false body cavity which is lined by patches of
mesodermal cells
• The false cavity is called as ‘pseudocoel’
• Example: Phylum Aschelminthes

3. Coelomates:
• Animals having a true body cavity
• Present in triploblastic animals
• The mesoderm splits into 2 layers enclosing a body cavity called coelom
• The cavity is filled with ‘coelomic fluid’
• In some animals like cockroach, coelom is filled with blood, hence it is
called as ‘haemocoel’

5. Body segmentation
• It is also called as ‘metamerism’ (true segmentation)
• It is a series of segments arranged along the body of the animal
• When the external segmentation matches with the internal
segmentation, such animals are called as ‘metamerically segmented
animals’
• Example: Earthworm

6. Body Support
• The internal or external framework which provides support to the
body is called as skeleton
• It is of 2 types. Exoskeleton (outside) & endoskeleton (inside)
• Lower animals have only exoskeleton for protection. Example:
cockroach
• Higher developed animals have both exoskeleton & endoskeleton
for their protection. Example: fish, cobra, parrot, man, etc

ANIMAL CLASSIFICATION

SALIENT FEATURES OF NON-CHORDATES

Phylum: Porifera (Pore bearing)
• Simplest pore bearing organisms
• May be solitary, colonial or sedentary
• Mostly marine, some are fresh water
• Vase shaped or cylindrical body
• Body shows cell aggregate plan, no tissues or organs
• Ostia are the small pores through which water enters the body &
osculum is the opening through which water exits the body

• Body cavity is called ‘spongocoel’
• ‘Choanocytes’ help in digestion (digestive system absent)
• Exoskeleton made up of silica, CaCO3 or protein spongin fibres
• Porifera feed on detritus material present in water (decaying)
• Asexual reproduction by budding, sexual reproduction by gametes
• Sponges have great power of regeneration
• Examples: Sycon & Euspongia

Phylum: Cnidaria (coelenterata)
• Colonial or solitary forms
• Sedentary or free living animals
• Most are marine but few may be found in fresh water (Hydra)
• Body is radially symmetrical
• Presence of specialized cells called as ‘cnidocytes’ which contain
stinging structures called as ‘nematocysts'

• Cnidocytes are present in tentacles help in capturing large prey as
their nematocysts discharge toxin into them
• Tissue level organization is seen for the first time in Cnidaria
• Due to blind sac body plan, mouth & anus are the same
• Body cavity called ‘coelenteron’ helps in digestion & circulation
• Two types of body forms: polyp & medusa
• Polyps are sedentary & cylindrical life forms

• Medusa are free swimming & umbrella shaped
• Mouth is surrounded by tentacles which help in locomotion &
capturing prey
• Poorly developed nervous system forming nerve net
• Asexual reproduction: budding, sexual reproduction: gametes
• Sea anemone are polyp type cnidarians, jelly fish are medusa type
• Corals are used in jewellery & they form coral reefs

Phylum: Ctenophora
• Exclusively marine animals
• Radially symmetrical body which is diploblastic
• Animals are called ‘comb jellies’
• Spherical body with external rows of cilia
• They exhibit bioluminescence (emission of light)
• Sexual reproduction with external fertilization
• Examples: Ctenoplana, Pleurobrachia

Phylum: Platyhelminthes (flat worms)
• Bilaterally symmetrical animals with blind sac body plan
• Most are endoparasites, few are free living
• Body is leaf like or ribbon like, unsegmented, dorso-ventrally flattened &
covered by ‘cuticle’
• Parasitic forms show ‘suckers’ or ‘hooks’ for attachment to the host
• In parasitic form digestive system is absent, if present it has only one
opening
• Excretory system is made up of flame cells

Hooks
Sucker

• Nervous system is in the form of nerve rings or nerve cords
• Reproductive system is well developed, animals are mostly
hermaphrodite (bisexual) as both male & female sex organs are
present on the same body
• Great power of regeneration
• Locomotory structures & sense organs are absent
• Examples: Tapeworm, liverfluke

Phylum: Aschelminthes (thread worms)
• Commonly called as ‘round worms’
• Most are parasitic living in body fluids of host
• Body is long & cylindrical which is thread like
• Bilaterally symmetrical animals which are pseudocoelomate
• These animals show ‘tube within a tube’ type body plan
• Body wall shows longitudinal muscles but no circular muscles
• Excretion takes place by protonephridia

• Nervous system has nerve rings & nerve
• Sexes are separate (unisexual) & animals show ‘sexual dimorphism’.
e.g. Male ascaris is shorter than the female
• Male ascaris has a curved posterior end with a pair of penial setae
for reproduction
• Female ascaris is longer with a relatively straight posterior
• Examples: Ascaris, Wuchereria & Dracunculus

Phylum: Annelida (Ring worms)
• Commonly called as ‘ring worms’
• Most are free living, few may be parasitic
• Some are burrowing & occur in moist soil
• These are bilaterally symmetrical & are first true ‘coelomates’
• Body is soft, elongated, cylindrical & metamerically segmented
• Complete digestive system
• Locomotion occurs with setae, parapodia or suckers

• Well developed longitudinal & circular muscles help in locomotion
• Respiration occurs through body surface
• Excretion occurs by ‘nephridia’
• Circulatory system is of the closed type
• Hb is dissolved in the plasma
• Nervous system is made up of nerve ring & ganglionated nerve cord
• Mostly bisexual but few may be unisexual
• Ectoparasites like leech suck vertebrate blood
• Examples: Nereis, earthworm (Pheretima), leech (Hirudinaria)

Pair of Ganglia

Phylum: Arthropoda (Jointed legs)
• Largest & most successful phylum
• Arthropods are solitary or colonial, most are free living
• They are omnipresent & bilaterally symmetrical
• Body covered by a tough ‘chitinous cuticle’
• Arthropods undergo ‘moulting’ to allow body growth
• Body is divided into head, thorax & abdomen
• In some animals head & thorax fuse to form ‘cephalothorax
• Arthropods possess legs for crawling, creeping, walking & wings for flying

• Digestive system is complete and divided into: foregut, midgut & hindgut
• Mouth parts are highly evolved & used for biting , chewing & sucking
• Circulatory system is of the open type, blood flows in open sinuses & bathes
the organs
• Respiratory organs are gills, trachea, book lungs & book gills
• Excretion takes place by green glands/ malphigian tubules
• Nervous system is formed by nerve ring & double ganglionated nerve cord
• Sense organs are well developed in the form of antennae, compound eyes &
taste receptors
• Sexes are separate showing sexual dimorphism
• Animals are ‘oviparous’ & fertilization is internal

• Development is direct or indirect (metamorphosis)
• In some arthropods like honey bees, individuals are produced by
parthenogenesis (without fertilization)
• Some arthropods are economically important like honey bees, silk worm,
lobsters, prawns, crabs, etc
• Some arthropods are harmful like mosquitoes, centipede, spiders,
cockroaches, etc
• Examples: Cockroach, butterfly, scorpion, centipede, crab, grasshopper, ants,
etc

Metamorphosis

Phylum: Mollusca (soft bodied)
• This phylum includes soft bodied animals
• They are free living or sedentary
• They are mostly marine while some are marshy
• They show ‘tube within tube’ body plan
• Most are bilaterally symmetrical but some are asymmetrical due to ‘torsion’ in
shells
• Body is divided into head, foot & visceral mass
• Visceral mass is enclosed in thick muscular fold of body wall called ‘mantle’

Torsion in molluscs

• Mantle secretes a hard calcareous shell which may be external, internal or
absent
• Molluscs feed on plant and animal matter
• Locomotion is by arms or foot. Foot is modified for burrowing & swimming
• Digestive system is well developed (intestine is U shaped because of torsion in
gastropods)
• Buccal cavity has a tongue like organ (rasping organ) called ‘radula’ which has
teeth
• Terrestrial molluscs may show lungs, aquatic molluscs show numerous gills
called ‘ctenidia’
• Circulatory system is of ‘open type’ (except in sepia)
• Blood contains blue coloured respiratory pigment called ‘haemocyanin’

Sepia & its internal shell

• Excretion occurs by kidneys, also called as ‘Organ of Bojanus’
• Nervous system is formed by 3 pairs of ganglia: cerebral ganglia in head,
pedal ganglia in foot & visceral ganglia in visceral mass
• Sense organs such as eyes, tentacles & osphradia (for testing purity of
water)
• Sexes are separate
• Animals are mostly oviparous
• Development is direct or indirect
• Examples: Chiton, octopus, Sepia, Pila

Chiton dorsal &
ventral surfaces

Phylum: Echinodermata (spiny skin)
• These are spiny skinned animals
• They are exclusively marine, solitary, sedentary or free living, colonial &
benthoic
• They have radial symmetry with ‘pentamerous symmetry’
• Bodies are spherical, elongated or star shaped
• Body does not have a well defined head
• Spiny exoskeleton present made up of calcareous plates
• Presence of a ‘water vascular system’ in the body for locomotion

• The water enters the water vascular system through an opening called as
‘madreporite’
• Echinoderms are carnivorous, and mainly feed on molluscans
• They move with their arms & tube feet (suckers present on arms)
• Respiration is by peristomial gills
• Circulatory system is greatly reduced, it is of open type & heart is absent
• Nervous system is simple with a ring around the mouth & radial nerves in the
arms
• Sexes are separate & fertilization external, development indirect
• They show a high power of regeneration
• Examples: Star fish, sea urchin, brittle star & sea cucumber

Phylum: Hemichordata (Half chordate)
• Exclusively marine animals usually living at the bottom of the sea
• Most are free living, some may be sedentary
• Body is soft, fragile, vermiform & unsegmented
• Body is divide into 3 parts: proboscis, collar & trunk
• Buccal cavity gives rise to a rod like structure which is considered as
notochord by some scientists
• They feed on microorganisms present in water

• Proboscis helps to make burrows while entire body brings about
movement
• Alimentary canal is complete, straight or ‘U’ shaped
• Respiration occurs by paired gills
• Gills open as gill slits
• Circulatory system is simple and closed type
• The blood is colourless
• Nervous system is embedded in epidermis on both dorsal and ventral
sides
• The sexes are separate

• Fertilization is external and development is indirect through free
swimming larva
• This phylum is the connecting link between non-chordates & chordates
• Examples: Balanoglossus, Saccoglossus

SALIENT FEATURES OF CHORDATES

Phylum: Chordata
• These animals show a the presence of cartilagenous notochord atleast in early
embryonic life
• Presence of gill slits in the pharyngeal region
• Presence of a hollow dorsal nerve cord running through the body length
• Animals which have a notochord but do not have a vertebral column are called
as ‘invertebrate chordates’
• These invertebrate chordates are a link between ‘non-chordates’ &
‘vertebrates’
• Invertebrate chordates are of 2 types: ‘Urochordata’ & ‘Cephalochordata’

• Phylum Chordata is divided into 3 sub-phylums
Phylum:
Chordata
Subphylum:
Urochordata
Subphylum:
Cephalochordata
Subphylum:
Vertebrata

Subphylum: Urochordata
• These animals are called ‘tunicates’
• Body is soft & covered by covering called as ‘test’ which is made up of
cellulose called ‘tunicine’
• Notochord is present only in the tail of the larva. It is lost during
metamorphosis
• Only marine animals
• Pharynx has many gill slits
• Examples: Herdmania, Salpa, Doliolum

Subphylum: Cephalochordata
• These are also called as ‘lancelets’
• They are small fish like animals that are not longer than 5cm in length
• They live partly buried in soft marine soil
• Notochord is present throughout the life and extends in length
• They show chordate characters such as presence of pharyngeal gill slits,
tail & dorsal nerve cord
• Examples: Amphioxus

Subphylum Vertebrata
• Notochord is replaced by vertebral column
• Subphylum vertebrata is divided into 2 divisions: ‘Agnatha’ (without jaws)
and ‘Gnathostomata’ (with jaws)
Division: Agnatha
• Includes the most primitive vertebrates without jaws
• Division Agnatha includes only one class i.e. Class Cyclostomata

Class Cyclostomata (circular mouth)
• Cyclostomes are jawless & ‘eel like’ animals
• Skin is soft, smooth containing unicellular mucous glands but no scales
• Median fins are present but paired fins are absent
• They are ‘ectoparasites’ which have sucking & circular mouth without jaws
• Endoskeleton is cartilagenous
• Digestive system lacks stomach
• Intestine is present with a fold call as ‘typhlosole’

• Respiration occurs by 5-16 pairs of gill slits
• Heart is 2 chambered
• Gonad is single & large without ‘gonoduct’
• Fertilization is external
• Examples: Petromyzon (lamprey) & Myxine (hagfish)

Division: Gnathostomata
• It is divided into 2 superclasses
1. Superclass: Pisces (bear fins)
2. Superclass: Tetrapoda (bear 4 limbs)

Superclass: Pisces
• These are aquatic animals
• ‘Poikilothermic’ or cold blooded animals (body temperature changes with the
surrounding temperature)
• They feed on detritus material, planktons, algae, molluscs & other aquatic
animals
• Locomotion is by body scales & fins
• ‘Caudal fin’ helps in steering
• Exoskeleton is made up of dermal scales
• Endoskeleton is either ‘bony’ or ‘cartilagenous’

• Body is streamlined & boat shaped
• Mouth is terminal or ventral in position
• Respiration is by gills
• Heart is 2 chambered & it shows single circulation which is closed
• Blood is red in colour due to red blood cells
• Pisces have a well developed brain with large ‘olfactory lobes’
• Sexes are separate
• Most fishes are oviparous & some are vivparous
• Superclass Pisces is divided into 2 classes

Superclass: Pisces
Class:
Chondrichthyes
Class:
Osteichthyes

Class: Chondrichthyes (cartilagenous fishes)
• Endoskeleton is in the form of a ‘cartilage’
• They are only marine
• Exoskeleton is made up of tiny ‘placoid scales’
• Mouth is ventral & there are 2 dorsal fins
• Male copulatory organ called ‘claspers’ are present
• Caudal fin is ‘heterocercal’ (asymmetrical)
• 5-7 pairs of gill slits are present. Operculum is absent

Placoid scales

• Fertilization is internal and these fishes are ‘viviparous’
• Examples: Shark (Scoliodon), electric ray, sting ray, hammerhead shark &
saw fish

Class: Osteichthyes (bony fishes)
• Endoskeleton is made up of bones
• These are found in fresh water & marine water
• Exoskeleton is made up of ‘cycloid’ or ‘ctenoid’ scales
• Mouth is terminal in position
• Single dorsal fin is present
• Claspers are absent
• Caudal fin is ‘homocercal’ (symmetrical)

• 4 pairs of gill slits are present covered by an operculum
• Fertilization is external & these fishes are ‘oviparous’
• Examples: Bombay duck, Pomphret, Catla, sea horse

Superclass: Tetrapoda (4 limbs)
• These animals bear 2 pairs of limbs or appendages
• Some animals like snakes are limbless
• Superclass tetrapoda includes 4 classes
Superclass:
Tetrapoda
Class:
Amphibia
Class:
Reptilia
Class: Aves
Class:
Mammalia

Class: Amphibia
• These animals live on land as well as water
• They are poikilothermic animals & carnivorous
• Body divided into head, trunk & tail (Sometimes tail is absent)
• 2 pairs of limbs arise from each from the pelvic girdle & pectoral girdle
• In frogs webs are present between digits which help to swim
• Skin is moist, glandular with mucous membrane
• Prominent ear drums or ‘tympanic membranes’ are present on the head

• Intestine & digestive glands are well developed
• Circulatory system is of closed type & heart is 3 chambered & ventral
• RBCs are biconvex & nucleated
• Respiration is through skin, lungs & bucco-pharynx
• Nervous system is well developed
• Sexes are separate, these are oviparous, fertilization is external
• Development occurs in water & and is indirect ( metamorphosis)
• Examples: Frog, toad, salamander, Ichthyophis

Metamorphosis
3 chambered heart

Class: Reptilia
• These are crawling animals like cobra, crocodile, turtle
• They are the first true terrestrial vertebrates, few may be aquatic or semi-
aquatic found in marshy areas
• Most of them are carnivorous
• Locomotion is by limbs which have well developed ‘pentadactyl digits &
claws’ which help the animal to creep or crawl
• Reptiles are poikilotherms (cold blooded)
• Skin is dry, non-glandular & covered by epidermal scales, scutes or plates

Pentadactyl
digits with claws
Scutes
Scales
Plates

• Heart is incompletely 4 chambered & ventral & circulatory system is of
closed type (crocodile has perfectly 4 chambered heart)
• Ear drum is depressed
• Respiration is through lungs
• Brain is well developed
• ‘Olfactory lobes’ & ‘cerebellum’ are better developed than amphibians
• Sexes are separate & show prominent sexual dimorphism
• Fertilization is internal, reptiles are oviparous, they lay shelled eggs& show
little parental care (viper is viviparous)

Reduced ears

Incompletely 4
chambered heart
Completely 4
chambered heart

Class: Aves
• It includes flightless birds & flying birds
• Forelimbs are modified into wings for flying
• Hind limbs are used for walking or running
• Aquatic birds have webs between toes
• Body differentiated into head, neck, trunk & tail
• They are homeotherms (warm blooded) i.e. body temp. remains constant
• Exoskeleton is made up of feathers

Webbed feet

• Scales are present on hind limbs
• Skin is thin, dry & non-glandular
• Bones are hollow
• Jaws form the beak & teeth are absent
• Special organs such as crop & gizzard are present
• Blood is red due to RBCs (biconvex & nucleated)
• Heart is ventral in position & 4 chambered showing double circulation
• Respiration is by lungs having air sacs for buoyancy

• Brain is enlarged with well formed cerebellum
• Optic lobes are well developed, olfactory lobes are poorly developed
• Unisexual, sexual dimorphism, oviparous, internal fertilization
• Birds lay shelled eggs with yolk & albumin
• Birds build nests on trees
• Most are herbivores & some are carnivores
• Parental care is well seen along with seasonal migration
• Urinary bladder is absent & females show only the presence of left ovary
& oviduct to reduce body weight during flying

Class: Mammalia
• Mammary glands are present for nourishment of young ones
• Mammals are terrestrial, aquatic, aerial & arboreal
• Most are herbivores, few are carnivores & some are omnivores
• Locomotion is by limbs
• Body divided into head, neck, trunk & tail
• They are homeotherms (warm blooded)
• Exoskeleton is in the form of skin, hair, fur, nails, hooves

• Skin is glandular having sweat glands & sebaceous glands
• Body cavity is divided into 2 parts: thoracic cavity & abdominal cavity by a
diaphragm
• Mammals show the presence of an external ear
• Teeth are of different types: I, C, M, PM
• Heart is completely 4 chambered with double circulation
• RBCs are biconcave & without a nucleus (except camel)
• Blood is red in colour
• Respiration is by lungs

• Brain is highly developed
• Cerebrum shows transverse band called as ‘corpus callosum’
• Optic lobes are better developed than olfactory lobes
• Few mammals are oviparous e.g. Duck billed platypus
• Some mammals have pouches for development of young ones. These
mammals are called as marsupials. e.g. Kangaroo
• Most mammals are placental & viviparous

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