Animal kingdom
Basis of classification
There are certain features which are
used as the basis for animal
classification.They are
1.Levels of organisation-cellular
level,tissue level,organ level & organ
system level.
2.Symmetry-asymmetrical,radial
symmetry,bilateral symmetry.
3.Diploblastic & triploblastic
organisation.
4.Coelom- coelomates,pseudocoelomates &
acoelomates.
5.Segmentation-presence(metamerism) or
absence.
6.Notochord –chordates & non chordates.
Based on these features,animals are
classified into different phylum
1.Phylum Porifera
2.Phylum Coelenterata(Cnidaria)
3.Phylum Ctenophora 8.Phylum Mollusca
4.Phylum Platyhelminthes 9. Phylum
5.Phylum Aschelminthes
Echinodermata
6.Phylum Annelida 10.Phylum hemichordata
7.Phylum Arthropoda 11.Phylum chordata
• Phylum Porifera
(e.g.sycon,Euspongia,Spongilla)
1.Commonly known as sponges.
2.Generally marine,asymmetrical & have
cellular level of organisation.
3.Water enters through minute pores in the
body wall called ostia into a central cavity
spongocoel & goes out through
osculum.Choanocytes or collar cells line
the spongocoel.
4.Digestion is intracellular.
5.Body supported by a skeleton made up of
spicules.
6.Sexes not seperate(hermaphrodite),eggs &
sperms are produced by the same
individual.Asexual reproductionfragmentation.Sexual reproductionformation of gametes.
7.Fertisation is internal & development
includes a larval stage.
• Phylum Coelenterata(Aurelia, Adamsia)
1.They are mostly marine,sessile or free
swimming,radially symmetrical animals.
2.Are diploblastic with tissue level of organisation.
3.Tentacles have cnidoblasts or cnidocytes which
contain stinging capsules or nematocytes.
4.Digestion is extracellular & intracellular.They have
a central gastrovascular cavity with a single
opening called hypostome.
5.Skeleton composed of calcium carbonate in case of
corals.
6.They exist in 2 body forms-polyp & medusa.
Polyp is a cylindrical & sessile form
e.g.Hydra,Adamsia.
Medusa is umbrella shaped & free swimming.
e.g. aurelia
Some exist in both forms exhibiting alternation of
generation(metagenesis), polyp undergo asexual
reproduction producing medusa & medusa sexually
produce polyp. e.g.Obelia
• PhylumCtenophora
(Pleurobrachia,Ctenoplana)
1.Commonly known as sea walnuts or comb
jellies.
2.They are marine,radially
symmetrical,diploblastic organisms with
tissue level of organisation.
3.The body bears 8 rows of ciliated comb
plates which help in locomotion.
4.Digestion is both extracellular &
intracellular.
5.Bioluminescence is well marked in
ctenophores.
6.Sexes are not separate.
7.Reproduction is sexual.
8.Fertilisation is external & indirect
development,
Phylum Platyhelminthes
(Teania,Fasciola)
1.They have dorsoventrally flattened
body,hence called flat worms.
2.They are mostly endoparasites found in
animals including human beings.
3.Flatworms are bilaterally
symmetrical,triploblastic & acoelomate
animals with organ level organisation.
4.Absorb nutrient from host.Hooks & suckers
present in parasitic forms.
5.There are specialised cells called Flame
cells which help in osmoregulation &
excretion.
6.Sexes not separate,fertilisation is internal
& development indirect.
• Phylum Aschelminthes
(Ascaris,Ancylostoma)
1.Body is circular in cross section & hence
called round worm.
2.They are free living,aquatic or terrestrial or
parasitic forms.
3.They are bilaterally
symmetrical,triploblastic,pseudocoelomate
animals with organ system level of body
organisation.
4.Alimentary canal is well developed with a
muscular pharynx.
5.There are excretory tubes which removes
waste through body pores.
6.Sexes separate,fertisation is internal &
development may be direct or indirect.
• Phylum Annelida
(Nereis,Pheretima,Hirudinaria)
1.They may be aquatic or
terrestrial,freeliving or parasitic.
2.Body is divided into segments or
metameres,hence the name annelida.
3.They are triploblastic,metamerically
segmented coelomate animals with
bilateral symmetry & organ system level of
body organisation.
4.Lateral appendages called parapodia which
help in swimming.
5.A closed circulatory system is present.
6.Osmoregulation & excretion is done with
the help of specialised structures called
nephridia.
7.Neural system well developed.
8.Dioecious or monoecious.Reproduction is
sexual.
• Phylum Arthropoda(Apis,Bombyx,Aedes)
1.They have jointed appendages,hence the name
arthropoda.
2.They are bilaterally
symmetrical,triploblastic,segmented,coelomate
animals with organ system level of organisation.
3. The body covered with exoskeleton is divided into 3
regions- head,thorax & abdomen.
4.Respiratory organs are gills,book lungs or trachea.
5.Circulatory system is open type.
6.Sensory organs are antennae,eyes.
7.Balance organs called statocysts are present.
8.Excretion through tubule like structures called
malpighian tubules.
9.Mostly dioecious.Fertilization is internal.Mostly
oviparous.Development is direct or indirect.
10.Largest phylum of animalia.
• Phylum Mollusca(Pila,Octopus)
1.They are terrestrial or aquatic,bilaterally
symmetrical,triploblastic,coelomate
animals with organ system level of
organisation.
2.Unsegmented body is covered by a
calcareous shell & is divided into
head,muscular foot & visceral hump.
3.A soft & spongy layer of skin forms a
mantle over the visceral hump.The space
between hump & mantle is called mantle
cavity.
4.Respiration & excretion is well developed.
5.The anterior head like structure have
sensory tentacles.Mouth has rasping organ
called radula.
6.Dioecious,oviparous& indirect
development.
• Phylum Echinodermata (Asterias,Ophiura)
1.These animals have spiny ossicles on their
body,hence the name echinodermata.
2.They are marine,radially
symmetrical(larvae bilaterally
symmetrical),triploblastic,coelomate
animals.
3.Digestive system is complete with mouth
on the lower side & anus on the upper side.
4.Presence of water vascular system which
helps in locomotion,respiration & capture
& transport of food.
5.Excretory system is absent.
6.Sexes separate.Reproduction
sexual.Fertilisation is
external.Development is indirect with free
swimming larva.
Phylum Hemichordata
(Balanoglossus,Saccoglossus)
1.They are worm like marine
animals,bilaterally
symmetrical,triploblastic,coelomate
animals with organ system level of
organisation.
2.The body is cylindrical & is composed of an
anterior proboscis,a collar & a long trunk.
3.Circulatory system is of open type.
4.Respiration takes place through gills.
5.Excretory organ is proboscis gland.
6.Sexes separate.Fertilisation
external.Development is indirect.
• Phylum Chordata
Chordates are characterised by
the presence of:
1.A notochord
2.A dorsal hollow nerve cord.
3.Paired pharyngeal gill slits.
• Class Cyclostomata
(Petromyzon,Myxine)
1.They are ectoparasites.
2.They have a elongated body bearing
6-15 pairs of gill slits for respiration.
3.Circular mouth without jawssucking in function.
4.Body is devoid of scales & fins.
5.Circulation is of closed type.
6.Cyclostomes are marine but for
spawning migrate to
freshwater,after spawning they
die.Larvae undergoes
metamorphosis & return to ocean.
Class Chondrichthyes(Scoliodon,Pristis)
1.They are marine animals with streamlined
body & cartilaginous endoskeleton.
2.Poikilothermic animals with persistent
notochord.
3.Mouth is located ventrally,gillslits
separate,operculum absent.
4.The skin is tough with placoid scales.
5.Jaws are very powerful.
6.Air bladder absent.
7.Heart is two chambered-one auricle & one
ventricle.
8.Some have electric organs-Torpedo &
some with poison sting-Trygon.
9.Sexes separate.Internal fertilisation.Mostly
viviparous.
• Class Osteichthyes
(Exocoetus,Hippocampus,Labeo,Catla)
1.Marine & fresh water fishes,stream lined
body with bony endoskeleton.
2.Poikilothermic animals.
3.Mouth is terminal,four pairs of gills covered
with operculum.
4.Skin is covered with cycloid or ctenoid
scales.
5.Air bladder is present regulating buoyancy.
6.Heart is two chambered.
7.Sexes separate.Fertilisation is
external.Mostly oviparous.
• Class Amphibia (Rana,Hyla,salamandra)
1.Poikilothermic animals ,aquatic as well as
terrestrial with two pairs of limbs.
2.Body divisible into head & trunk.Tail
present in some.
3.Skin without scales.
4.Eyes have eyelids.
5.Tympanum represents the ear.
6.Respiration is by gills,lungs & through skin.
7.Alimentary canal,urinary & reproductive
tracts open into a common chamber called
cloaca.
8.Respiration is by gills,buccal & through
skin.
9.The heart is three chambered-2 auricles &
1 ventricle.
10.Sexes separate.Fertilisation
external.Oviparous.Development indirect.
• Class Reptilia
(Chelone,Chameleon,Alligator)
1.Creeping or crawling mode of
locomotion & hence the name
characterised by two pairs of limbs.
2.Mostly terrestrial,body is covered by
dry & cornified skin-presence of
scales or scutes.
3.Tympanum represents the ear.
4.Heart is three chambered.One
exception is crocodile which is 4
chambered.
5.Sexes separate.Fertilisation
internal.Oviparous.Development
direct.
• Class Aves (Pavo,Psittacula,Struthio,Corvus)
1. Homeiothermic animals
characterised by the presence of feathers &
beaks,capable of flying.
2.The fore limbs are modified into wings & hind
limbs generally have scales & are modified for
walking,swimming or clasping the branches.
3.Skin is dry without glands except the glands at
the base of the tail.
4.Bony endoskeleton with air cavities-pneumatic
bones.
5.Heart is completely four chambered.
6.Air sacs are connected to lungs which also aid
in respiration.
7.Sexes separate.Fertilisation
internal.Oviparous.Development direct.
• Class Mammalia
(Pteropus,Ornithorhynchus,Macropus)
1.Characterised by the presence of
mammary glands by which the young ones
are nourished.
2.They have two pairs of limbs adapted for
walking,running,climbing,burrowing e.t.c.
3.Homeiothermic animals with hairs on their
skin.
4.External ears or pinnae is present.
5.Different types of teeth present.
6.Heart four chambered.
7.Respiration by lungs.
8.Sexes separate.Fertilisation
internal.Viviparous.Development direct.