Taxonomy of Finfish (1+2)

4.2.3 Squamata Snakes and Lizards

Kingdom         : Animalia

Phylum            : Chordata

Subphylum      : Vertebrata

Class                : Reptilia

Order               : Squamata

Suborder         : Serpentes

Superfamily     : Xenophidia (Colubrids, vipers, and relatives)

Family             : Hydrophiidae (sea snakes)

17 genera and 51 species of true sea snakes are under this family

Example: Aipysurus laevis (common sea snake)

Order : Squamata

• It includes lizards and snakes. 
• They are most successful living reptiles.
• Squamata are the reptiles in which the skull has lost both temporal vacuities. E.g.: snakes and some lizards. 
• Cloacal aperture is transverse.
• Ribs are single headed.
• Quadrate is movable.
  • Vertebrae are procoelous.

Characters of true sea snakes

• Have a flattened body
• A short oarlike tail,
• Valvular nostrils on top of the snout
• Elongated lungs that extend the entire length of the body.
• Very small scales, usually not overlapping (juxtaposed), abutting against one another like paving stones.
• Reduced belly scales in primitive species; absent in more advanced forms
• Advanced species cannot crawl and are thus helpless on land.
• When swimming, a keel is formed along part of the belly, increasing surface area and aiding propulsion, which occurs by lateral undulation.
• Sea snakes can remain submerged for several hours, possibly as much as eight or more. This remarkable feat is partly due to the fact that they can breathe through their skin.

 Family:  Colubridae: Freshwater snakes:

• Xenochrophis piscator is a common species of non-venomous fresh water snake found in India.
• They can be identified  by a  uniform chess-board pattern of black spots on its body  and has two tear-marks just below the eyes. 
• Feeds mainly on small fishes and water frogs.