Write short note on Reptilia.

Explanation

The class name refers to their creeping or crawling mode of locomotion (Latin, repere or reptum, to creep or crawl).
They are mostly terrestrial animals and their body is covered by dry and cornified skin, epidermal scales or scutes.
They do not have external ear openings.
Tympanum represents ear.
Limbs, when present, are two pairs.
Heart is usually three-chambered, but four-chambered in crocodiles.
Reptiles are poikilotherms.
Snakes and lizards shed their scales as skin cast.
Sexes are separate.
Fertilisation is internal.
They are oviparous and development is direct.
Examples : Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Calotes (Garden lizard), Crocodilus (Crocodile), Alligator Alligator). Hemidactylus (Wall lizard), Poisonous snakes - Naja (Cobra), Bangarus (Krait), Vipera (Viper)
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