Trionyx is identified by its soft leathery shell, pointed nose and long neck, there are many different species, including some from a different family found in Africa. Soft shells have long, highly mobile and flexible necks; they have an aggressive disposition: Holding and restraining a soft shell is somewhat dangerous as they can reach amazingly far back alongside the carapace to bite the hand that holds them.
Five of the more common species kept are :-
Trionyx spiniferous (Spiny soft shell) N, America and Canada, shell length reaching 36cms (14") females, (18cm), (7') males. This species gets its name from the conical projections along the front margin of the carapace, There are six sub species.
Trionyx ferox (Florida soft shell) N, America, this is the largest N, American species with females reaching a length of 46 –51 cm (18-20"), males being such smaller, Juveniles show a distinct brown spots on the carapace.
Trionyx muticus (Common / smooth soft shell) N,America and Mexico, length reached 28cms (11”) for females, 20cm (8’’) in males, As the name implies, the carapace is smooth and devoid of tubercles.
Trionyx gangeticus (Ganges soft shell) India, Bangladesh, Nepal and Pakistan, both sexes reach a maximum shell length of 69cm (27”), Juveniles have a greenish carapace with a reticulated pattern while adults are a dull olive.
Trionyx sinensis (Chinese soft shell) China and Taiwan, maximum length 25cms (10"), The colour can be varied but generally they are olive above and lightish yellow below.
Soft shell turtles are almost wholly aquatic but come ashore when the weather is favourable to sunbathe and for egg laying, The long neck and protruding nose enables them to reach the surface of the water and 'Snorkel' with the minimum of surface disturbance thus concealing themselves and their hiding place from predators, Most soft shells are very shy and appreciate a hiding place under water, but this must be built so that there is no danger of it collapsing on top of the reptile. Sexing soft shell turtles is difficult. Upon reaching sexual maturity males pursue females, often biting at the neck and limbs in an attempt to subdue her and so allow him to mount. Male soft shells are generally smaller than the females, the females being larger to allow for the development of eggs.
Trionyx lay their eggs in sand or mud on the banks of the river, stream or pool in which they live, Captive soft shells tend to lay their eggs in the water of the tank if they are not provided with a nesting area of warm sand, The shell, as the name suggests, is soft and leathery to the touch and the carapace has a very even rounded shape, The drab olive or brown of the shell in most species acts as a camouflage for the reptile as it lies motionless in the mud or sand at the bottom of a stream, river or swamp bed waiting for its prey to swim within reach, Soft shells snatch their prey and devour it under water.
The most common foods eaten are water snails, molluscs, crayfish, insects and other water invertebrates, fish, tadpoles, frogs, worms, also algae, and water weeds. Some insects, such as crickets and locusts which land accidently on the water surface are eagerly snatched.
The spiny softshell is known to eat a lot of water vegetation and has been known to devour water melon, Despite the name and the fact that the shell is softer than other chelonians these turtles do require calcium and phosphorus in their diet, given in the form of vitamin and mineral supplements. Vitamin D3 is essential for the assimilation of these minerals, which is why a suitably balanced supplement such as Nutrobal must be provided with all food given to those in captivity, Whole fish, whole molluscs, whole prawns and crayfish have the correct balance of vitamins and minerals, but when feeding crickets, locusts or other purpose bred insects ensure that these are fed a supplement for the 24 hours before they are offered so that the insects have eaten sufficient before themselves being eaten.
The accommodation for soft shells should consist of as large a tank as possible with a depth of water enabling them to 'Snorkel' whilst still resting on the bottom of the tank. Remember that many species grow pretty large , A temperature of 25-30°C (75-86°F) is needed to enable the turtle to feed and digest its food. Soft sand may be used as a sub-strata but this is not entirely necessary as it may block the filter. Some form of underwater retreat is desirable for the more shy specimens, A flat smooth board across two smooth rocks or stones with a sloping access ramp provides a shelter below and a basking area above for the soft shell, Any land area provided must be absolutely smooth otherwise the plastron will be damaged and lead to infections, This is a very important factor in keeping soft shell turtles and any tank decoration such as stones and bogwood should be carefully inspected for any sharp or rough edges, The soft shell turtles rarely emerge to bask but artificial ultra violet lighting such as a Gro-lite or True-lite will be beneficial to the turtle, On very warm sunny days the soft shell can be placed outside in an enclosed pool for a few hours to reap the Benefit of natural sunlight and fresh air. A thermostatically controlled water heater,as sold for tropical fish tanks, is needed to keep the water temperature in the 25-30°C region, but special precautions must be taken to protect it from being bitten by the turtle, hiding it and the electric cable under smooth stones. Many turtles burn their feet by standing on the heater. The use of a power filter will keep the water free of floating debris, A complete change of water should be made at least once a month, If a filter system is not used, daily changes of water will be necessary, Good air circulation in the top of the tank is needed to prevent the turtle breathing stagnant air, Train your turtle from the start to feed in a separate smaller tank, this will keep the main tank free of foul smelling food debris and it is such easier to clean a small tank daily than the large living quarters.
The most common ailments in soft shell Turtles are:
- swollen eyes with closed eyelids..... Often caused by a lack of Vitamin A in the diet.
- Deformed shells and soft bones.... Caused by insufficient minerals and vitamin D in the diet.
- Abrasions to the shell .... Caused by sharp or rough edges on tank ornaments.
- Burns… These are caused by not having the water heater suitably protected.
- Infections on the shell ….. These are due to poor hygiene in the tank and therefore overgrowth of both fungi and bacteria.
References Pritchard P.C,H 1979 Encyclopedia of Turtles. T.F.H. Publications