Phylum Chordata

Phylum Chordata

» Notochord is present in it.
» All the chordates are triploblastic, coelomate and bilaterally symmetrical.
» A dorsal hollow tubular nerve cord and paired pharyngeal gill slits are other features of chordates.

According to classification there are two subphyla in Chordata.
(a) Protochordates
(b) Vertebrata

Some main groups of phylum Chordata

1. Pisces

» Aquatic life
» All these are cold blooded animals.
» Its heart pumps only impure blood and have two chamber
» Respiration takes place through gills.
Example - Hippopotamus, Scoliodon, Torpedo etc.

2. Amphibia

» Found both on land & water
» All these creatures are amphibian.
» All these are cold-blooded.
» Respiration takes place through gill, skin and lungs Heart have three chamber two auricles and one ventricle.
Example - Frog, Necturus, Toad etc. Icthyophis, Salamander.

3. Reptilia

» Crawlling animal
» Land vertebrate, cold-booded, terrestrial or aquatic vertebrates.
» It contains two pair of limbs.
» The skeleton is completely flexible.
» Respiration takes place through lungs.
» Its eggs are covered with shell made up of Calcium carbonate.
Example - Lizard, snake, tortoise, crocodile, turtle, sphenodon etc.

1. Mesozoic era is called the era of reptiles.
2. Cobra is the only snake which makes nests.
3. Cobra emits their venom through fangs.
4. Heloderma is the only poisonous lizard.
5. Sea snake which is called Hydrophis is the world's most poisonous snake.

4. Aves

» Warm blooded tetrapod vertebrates with flight adaptation.
» Its fore-feet modified into wings to fly.
» Boat shaped body is divisible into head, neck, trunk and tail.
» Its respiratory organ is lungs.
» Birds have no teeth. Beak help in feeding.
» Beak is formed by jaw.
Example - crow, peacock, parrot etc.
1. Flightless Birds - Kiwi and Emus.
2. Largest alive bird is Ostrich.
3. Smallest bird is Humming-bird.
4. Largest zoo in India is Alipur (Kolkata) and the largest zoo of the world is Cruiser National Park in South Africa.

5. Mammalia

» Sweat glands and oil glands are found on skin.
» All these animals are warm blooded.
» Its hearts are divided into four chamber.
» Tooth comes twice in these animals (Diphyodont).
» There is no nucleus in its red blood cells (except in camel and lama).
» Skin of mammal have hair.
» External ear (Pinna) is present in mammal.
» Pinna is present in mammal.

Mammals are divided into three sub-classes :
1. Prototheria - It lays eggs ( Echidna ) .
2. Metatheria It bears the immature child ( Kangaroo ) .
3. Eutheria - It bears the well developed child ( Human )