Reptiles
The Reptiles class has about 6457 species and evolved from the primitive amphibians.
Birds and mammals have evolved from reptiles. Reptiles are the ectothermic animals and air breathing vertebrates.
Turtles are the most ancient reptiles and the snakes the most recent. Since the reptiles share many anatomical features with bird, both the reptile and birds are some times considered together in the single group entitled as “Sauropsida”.
Reptiles consists of chelonians, crocodiles, lizards, snakes etc. Reptiles are seen in all continents except Antarctica and on most islands.
Common Features of Reptiles
- Reptiles have no gills and lungs are present.
- Absence of no hair.
- Absence of feather.
- They either lay egg or give birth to young but in both instances the embryo, like that of a mammal is enclosed in an amnion.
- Whether hatched from an egg or born alive, the reptiles don’t pass through a larval stage or undergo metamorphosis as do amphibians.
- Reptiles are capable of growth through out the life.
- Dry water-proof skin with horny scales are present.
- Scales are not separated as seen in fish but they are folds of skin.
- Ecdysis is a common feature.
- Majority of the reptiles are carnivorous especially the snakes (Marine Green turtle and Green Iguana are herbivores).
Orders and Sub-Orders of Reptiles
Orders
There are three orders in reptilian group:
- Testudinata (Chelonia): This group comprises turtles, tortoises, terrapins and sea-turtles.
- Crocodilia: This group comprises crocodiles, caimans, alligators and gavials.
- Squamata: This group comprises lizards and snakes.
Sub-orders
- Amphisbaenia (Worm lizards)
- Sphenodontia (Tuatara in Newzealand)
- Serpentes (Ophidia) (Snakes)
- Lacertilia (Sauria) Lizards)
Distribution of Reptiles
Important Snakes
- Cobra (Naja naja naja)
- King cobra (Ophiophagus hannah)
- Krait (Bungarus caeruleus)
- Russell’s viper (Vipera russelli)
- Saw scaled viper (Echis carinatus)
- Indian Rock python (Python molurus)
- Reticulated python (Python reticulatus)
- Anaconda or South American Boa
- Sea snakes (Eg. Hook-nosed sea snake: Enhydrina schistosa)
Important Lizards
- Common Monitor (Varanus bengalensis)
- Water Monitor (Varanus salvator)
- Yellow Monitor (Varanus flavescens)
- Komodo dragon (Varanus komodoensis)
- Gila Monster (Heloderma suspectum)
- Beaded Lizard (Heloderma horridum)
- Worm Lizards (Bipes and Rhineura)
Important Crocodile, Ghavial, Caiman and Alligator
- Mugger or Marsh crocodile (Crocodylus palustris)
- Salt water crocodile or Estuarine crocodile or Indo-Pacific crocodile (Crocodylus porosus)
- Gharial or Ghavial (Gavialis gangeticus)
- Cayman (Caiman crocodilus)
- American alligator (Alligator mississippiensis)
- Chinese alligator (Alligator chinensis)
