Animal classification

Phylum: Protozoa
Phylum : Porifera
Sedentary, aquatic mostly marine, solitary or colonial
Radially symmetrical or assymetrical organisms
Porous body permeated with pores, canals and chambers
through which water current flows, with one to many internal
cavities lined with collar cells
Skeleton made up of Calcerous or siliceous or horny fibers
Body without definite organs, systems , mouth and nervous
Posses great power of regeneration
Both hermaphrodite and unisexual forms exist.
Phylum: Coelenterata
Characteristic of Phylum:
Body multicellular, with a definite form, generally radial
May be polymorphic, generally polyp and Medusa.
Body wall of two layers - ectoderm and endoderm.
Respiratory, excretory and vascular system absent.
Nervous system made up of a network of nerve cells and
Reproduction both asexually( by budding) and sexually
Sea Anemone
Phylum: Platyhelminthes
Characteristic of Phylum:
They have a dorsoventrally flattened body.
They include free living as well as parasitic forms.
The free-living flatworms live in springs, sands, streams or in
bodies of salt water.
Show Bilateral symetery
Body is covered with a cuticle in parasitic forms and with ciliated
epithelium in free living forms and also in free-living larval stages
of parasitic forms.
Excretory organs are protonephridia.
Digestive system may or may not be present.
Blood and skeletal system absent
Tape worm
Tape worm
It has an elongate, dorsoventrally flattened (hence
platyhelminthes), ribbon-like or tape-like body with many
segments called proglottids, hence the name cestoda. Body is
divided into three distinct regions: Head or scolex, neck and
The head or scolex is a minute, round knob-like structure about
the size of a pinhead. It bears hooks and suckers.
The neck is situated just behind the scolex. It is narrow, short,
unsegmented and represents an area of proliferation.
Characteristics of Phylum:
They are round worms showing bilateral symmetery, mostly
microscopic in size, but complex in organisation, possesing all
major physiological systems of higher animals except respiratory
and circulatory system.
They are cylindrical and slender tapering towards the end
The digestive system is tubular made up of three main regions
Oesophagus, intestine and rectum.
The excretory system opens to the exterior by a pore that is located
ventrally above the level of the nerve ring.
The nervous system consists of the nerve ring surrounds the
Ascaris lumbricoides
Ascaris lumbricoides
Commonly known as roundworm, and is a parasite occurring in
man, especially among children. The chief structural features are as
It has an elongate, cylindrical, unsegmented wormiform body
(Hence nematoda) yellowish brown body covered with a smooth
and tough elastic cuticle, which shows transverse striations at
frequent intervals.
There are four well-marked longitudinal lines, the dorsal and ventral
lines are thin and whitish in colour, while the two lateral lines are
thick and brownish in colour.
The mouth is situated at the anterior end and is guarded by three
lips, one mid-dorsal and two ventro-laterals.
The sexes are separate and there is a clear sexual dimorphism.
Phylum: Annelida
Characteristics of Phylum:
Bilaterally symmetrical and vermiform.
Body has more than two cell layers, tissues and organs.
Body cavity is a true coelom, often divided by internal septa.
Body possesses a true gut with mouth and anus.
Body possesses 3 separate sections, a prosomium, a trunk and a
Has a nervous system with an anterior nerve ring, ganglia and a
ventral nerve chord.
Has a true closed circulatory system.
Has no true respiratory organs.
Reproduction normally sexual and hermaphoditic.
The important characteristic features are as follows:
The body is metamerically divided into 33 segments.
There are two suckers, an anterior sucker and a posterior
sucker formed by the fusion of last seven segments. They are
the organs of adhesion.
The triradiate mouth is situated in the centre of the cup-like
cavity of the anterior sucker, and the anus is situated at the base
of-the-posterior sucker on the dorsal surface.
Phylum: Arthropoda
Charactersictics of Phylum:
The body segmented, the segments usually grouped in two or
three rather distinct regions
Paired segmented appendages
Bilateral symmetry
A chitinous exoskeleton, which is periodically shed and
renewed as the animal grows
A tubular alimentary canal, with mouth and anus
An open circulatory system
Excretion usually by means of tubes (the Malpighian tubules)
that empty into the alimentary canal, the excreted material
passing to the outside by way of the anus
Respiration by means of gills, or tracheae and spiracles
No cilia or nephridia
The sexes nearly always separate
The body is elongated, dark greenish-brown in colour,
dorsoventrally flattened and is divided into a distinct head and a
long, segmented trunk or body.
Head segments are closely fused. Head appendages are long
antennae, reduced maxillae and mandibles.
Body segments have 21 pairs of walking legs. The first pair of legs
is curved, clawed and forwardly directed to form maxillipedes or
poison claws, while the rest of walking legs have 7 joints. All
walking legs are similar, hence the name myriapoda.
Phyllum: Mollusca
Characteristic of Phylum:
Aquatic animals, mostly marine, a few freshwater and some
Adult body – plan is sharply defined and represents the tissue –
organ grade of body organisation.
The body is soft, unsegmented without jointed appendages
and made of 4 parts- the visceral mass, the head, the foot and
Fundamentally bilateral symmeterical.
The alimentary canal is simple and straight, often U shaped or
The respiratory organs consists of one to many comb- like gills
or ctenidia , at the base of which is usually present an olfactory
organ called osphradium.
The excretory system comprises one to six pairs of sac like
Characteristics of the Phylum:
Exclusively marine
Gergarious, mostly free living and creeping slowly on the sea
Body is triploblastic, coelomate and without segmentation.
Radial symmetry in adults and biradial symmetery in larvae
Shape of the body is star shape, spherical, globular, discoidal or
Echinoderms possess a unique water vascular system or
called Ambulacral system
They have a simple radial nervous system that consists of a
modified nerve - net — interconnected neurons with no central
Reproduction is entirely sexual. Sexes are separate.
Characteristics of Chordates
➢ Notochord
➢ Dorsal
nerve cord
➢ Pharyngeal pouches or gill slits
➢ Postanal tail
Phylum – chordata
Characterisistics of phylum:
Notochord or a rod of vacuolated cells, encased by a
firm sheath that lies ventral to the neural tube in
vertebrate embryos and some adults.
Hollow nerve cord that lies dorsal to the notochord
Pharyngeal pouches
➢ Ventral
Heart – heart located ventrally
Higher Classification of Chordata
➢ Phylum
Subphylum Urochordata – tunicates, sea squirts
Subphylum Cephalachordata – lancelets
Subphlum Vertebrata- vertebrates
: Chondrichthyes
Characterisistics of class:
Jaws with calcified teeth
Serially arranged vertebrae
Pectoral and pelvic girdles support paired fins
Skeleton composed of cartilage (no bone)
Placoid scales
Claspers on male pelvic fins
Body is divisible into head, trunk and tail.
Head is dorsoventrally compressed.
Tail fin is heterocereal.
The mouth is ventrally located and is crescent shaped
supported by jaws bearing teeth.
5 pairs of gill slits are present laterally between the mouth and
the pectoral fins (hence the name elasmobranchi).
There are two unpaired dorsal fins and a ventral fin present.
Class : Amphibia
Characteristics of class:
They are ectothermic vertebrates
Their skin is usually smooth and lacks scales, hair, and
They are dependent upon moisture and subject to desiccation
their skin must remain moist to aid in breathing.
They have three-chambered hearts.
Salamander is commonly known as European fire-salamander
and terrestrial in habit, lives in Moist areas.
For breeding needs water, hence the name Amphibia.
Body is lizard-like in appearance covered with slimy mucous
rich skin without scales.
The colour is black with yellow spots.
Limbs are well developed and strong.
Tail is cylindrical.
Gills are absent.
Eye-lids are movable.
Class : Reptilia
Characteristics of class:
Presence of lungs
Direct development without larval forms as in amphibians
a dry skin with scales but not feathers or hair
an amniote egg; internal fertilization
a three or four-chambered heart; two aortic arches (blood
vessels) carrying blood from the heart to the body.
metanephric kidney
Twelve pairs of cranial nerves
skeletal features such as limbs with usually five clawed fingers
or toes,
and an incomplete or complete partition along the roof of the
mouth, separating the food and air passageways so that
breathing can continue while food is being chewed
Naja naja is commonly called Indian cobra or nag.
Body is elongated measuring one and a half to two meters in length,
without limbs.
The colour of the body is brown or blackish.
Body is covered with smooth oblique scales and is arranged in 1525 rows (hence it is a reptilian).
Head is not differentiated from the neck. Neck is dilatable
laterally into a hood by cervical ribs.
The dorsal surface of the hood bears a biocellate mark
The lower surface of the hood bears two black patches.
Eyes are very small and with round pupils.
Poison fangs are followed by 1-3 small teeth.
Tail is cylindrical and tapering posteriorly.
: Aves
Fore limbs modified for flying
Hindlimbs adapted for walking, swimming or perching.
Epidermal feathers on the body
Endothermic (warm blooded)
Epidermal scales on legs and feet
Light weight bony skeleton with air cavities in some bones
Four chambered heart
Digestive system has a crop and a gizzard.
Syrnix ( voice box) is capable of producing two pure tones
Excellent vision
No bladder present, kidney produces uric acid
Salt gland present above the eyes.
Elaborate courtship rituals, internal fertilization and oviparous
The ducks are aquatic birds. Body is covered by feathers
(hence it belongs to Aves) coated with oil.
Beak is broad and depressed or flat (hence it belongs to Aves).
The upper and lower jaws are provided with lamellae, which
serve as sifting apparatus.
Toes are webbed.
Tongue is muscular.
: Mammalia
Characteristics of class:
Possess hair which is made of keratin.
4 chambered heart.
Mammary glands are used to produce milk to nourish their young.
The diaphragm is a muscle that separates the thoracic cavity from
the abdominal cavity.
7 cervical vertebrae (neck bones) are present in most mammals.
Most are viviparous though some are oviparous.
Teeth are embedded in the jaw bone and come in a variety of forms.
Well developed brain.
It is small in size and the body is covered with soft fur (hence it
belongs to mammalia).
Snout is short with or without nose leaf.
The wings are outgrowths of the body and support of the forelimbs.
The main part of the wing is called patagium.
Pinna is large and often provided with flags, serving as tactile
organs and also in making the power of hearing more acute.
Eyes are small and the vision is weak.
Tail is included in the inter-femoral membrane provided with a
distinct flap.
Only the thumb or first digit is clawed in the forelimbs. Hind limbs
are weak and have five clawed digits.
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