Classification of Trionyx (Soft River Terrapin)
- Phylum :- Chordata (Dorsal tubular nerve cord, notochord and gill-slits present.)
- Group :- Craniata (Definite head, Cranium with brain present.)
- Sub phylum :- Vertebrata (Vertebral column present.)
- Division :- Gnathostomata (Jaws and paired appendages present.)
- Super Class :- Tetrapoda (Paired limbs, lungs, cornified skin and bony skeleton.)
- Class :- Reptilia (Scaly vertebrates. Right and left aortic arches present. Single condyle. Pulmonary respiration. Embryo with amnion and allantois.)
- Sub Class :- Anapsida (Primitive reptiles. Skull completely roofed over.)
- Order :- Chelonia (Turtles, tortoises and terrapins.)
- Family :- Trionychoidae (Soft shelled turtles.)
- Genus :- Trionyx (Soft River Terrapin)
Geographical distribution
Trionyx is widely distributed in India, North America, Africa, Asia and Malayasia Archipelago. Cretaceous to Recent
Habit and habitat
Trionyx gangeticum is a common fresh-water and pond terrapin
General Characteristics of Trionyx (Soft River Terrapin)
- Commonly called as torto or soft river terrapin.
- Body is flat, oval and encased in bony shell.
- Skin is smooth and leathery.
- Body divided into head, neck, trunk and tail. Head is pointed with greenish or blackish longitudinal streaks.
- Lips are fleshy. Head contains, eyes, mouth and nostrils.
- Behind eyes are external ear opening. Dorsal surface is olive above and yellowish below.
- Carapace is fused with vertebral column and ribs.
- Carapace consists of 9 median vertebral plates corresponding to trunk vertebrae and fused with the flattened neural spines of corresponding vertebrae. To these a median nuchal and 2 precaudals are added.
- Lateral parts of carapace are composed of 8 costal plates. Marginal plates are added to costal and precaudals.
- Plastron best seen in inner surface consists of a pair of epiplastron, a median entoplastron and paired hyo, hypo and xiphiplastron.
- Only neck and tail vertebrae are movable. Feet are broadly webbed and only three inner digits are clawed.
Special Features
Oviparous. Eggs are laid outside water. Because of rigid shell the breathing movements are produced by protrusion of the head, movements of girdles, limbs and pumping action of hyoid.
Identification
Since this terrapin contains clawed digits, webbed feet and longitudinal streaks over head and above features, hence it is Trionyx.
