Trionychidae softshell turtle

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     The Trionychidae are a taxonomic family of a number of turtle genera, commonly known as softshell turtles. This family was erected by Leopold Fitzinger in 1826. Softshells include some of the world’s largest freshwater turtles, though many can adapt to living in highly brackish areas. Members of this family occur in Africa, Asia, and North America, with extinct species known from Australia. Most species have been included in the genus Trionyx, but the vast majority have since been moved to other genera (the North American Apalone softshells that were placed in Trionyx until 1987).

     Trionychidae are called “softshell” because their carapaces lack horny scutes (scales), though the spiny softshell, Apalone spinifera, does have some scale-like projections, hence its name. The carapace is leathery and pliable, particularly at the sides. The central part of the carapace has a layer of solid bone beneath it, as in other turtles, but this is absent at the outer edges. The light and flexible shell of these turtles allows them to move more easily in open water or in muddy lake bottoms. Having a soft shell also allows them to move much faster on land than most turtles. Their feet are webbed and three-clawed, hence the family name “Trionychidae,” which means “three-clawed“. The carapace color of each type of softshell turtle tends to match the sand or mud color of its geographical region, assisting in their “lie in wait” feeding methodology.

     Trionychidae have many characteristics pertaining to their aquatic lifestyle. Many must be submerged in order to swallow their food. They have elongated, soft, snorkel-like nostrils. Their necks are disproportionately long in comparison to their body sizes, enabling them to breathe surface air while their bodies remain submerged in the substrate (mud or sand) a foot or more below the surface.

     Females Trionychidae can grow up to several feet in carapace diameter, while males stay much smaller; this is their main form of sexual dimorphism. Pelochelys cantorii, found in Southeastern Asia, is the largest softshell turtle.

    The Ba Ba Gai (Pelodiscus sinensis, chinese softshell turtle) is a species of softshell turtle that is native to Inner Mongolia, Guangxi, Hong Kong, Taiwan, Russia, Korea, Japan, Vietnam (the spotted softshell turtle Pelodiscus variegatus).

    Most are strict carnivores, with diets consisting mainly of fish, aquatic crustaceans, snails, amphibians, and sometimes birds and small mammals. According to Ditmars (1910): “The mandibles of many species form the outer border of powerful crushing processes—the alveolar surfaces of the jaws“, which aids the ingestion of tough prey such as molluscs. These jaws make large turtles dangerous, as they are capable of amputating a person’s finger, or possibly their hand.

    Softshells are able to “breathe” underwater with rhythmic movements of their mouth cavity, which contains numerous processes copiously supplied with blood, acting similarly to gill filaments in fish. This enables them to stay underwater for prolonged periods.

Ba Ba Gai (Pelodiscus sinensis)

    The Ba Ba Gai (Pelodiscus sinensis, Chinese softshell turtle) is a species of softshell turtle that is native to Inner Mongolia, Guangxi, Hong Kong, Taiwan, Russia, Korea, Japan, Vietnam (the spotted softshell turtle Pelodiscus variegatus).

    Pelodiscus sinensis softshell turtles live in fresh and brackish water. These softshell turtles are found in rivers, lakes, ponds, canals, creeks with slow currents, marshes, drainage ditches. Ba ba gai softshell turtles often submerge their heads in water. This is because they carry a gene which produces a protein that allows them to secrete urea from their mouths. This adaptation helps them survive in brackish water by making it possible for them to excrete urea without drinking too much salty water. Rather than eliminating urea by urinating through their cloaca as most turtles do, which involves significant water loss, they simply rinse their mouths in the water.   

    These Ba Ba Gai are predominantly carnivorous and the remains of fish, crustaceans, mollusks, insects, seeds of marsh plants.

     Females of the Pelodiscus sinensis softshell turtle can reach up to 33 cm (13 inches) in carapace length, while the smaller males reach 27 cm (11 inches), but however have longer tails than the females. Maturity is reached at a carapace length of 18–19 cm (7–7.5 inches). It has webbed feet for swimming. These Ba Ba Gai reach sexual maturity sometime between 4 and 6 years of age. They mate at the surface or under water. A male will hold the female’s carapace with its forelimbs and may bite at her head, neck, and limbs. Females may retain sperm for almost a year after copulation. The females lay 8–30 eggs (about 20 mm or 0.79 inch in diameter) in a clutch (about 76–102 mm or 3–4 inches) and may lay from 2 to 5 clutches each year. The eggs are laid in a nest that is  across at the entrance. After an incubation period of about 60 days, which may be longer or shorter depending upon temperature, the eggs hatch. Average hatchling carapace length and width are about 25 mm (1 inch). Sex of the hatchlings is not determined by incubation temperature.

Ba Ba Tron (Wattle-necked softshell turtle)

     The Wattle-necked softshell turtle (Palea steindachneri*), also commonly known as Steindachner’s soft-shelled turtle, is an endangered Asian species of softshell turtle in the family Trionychidae. The species is the only member of the genus Palea. They is native to Southeastern China (Guangdong, Guangxi, Guizhou, Hainan, Yunnan), Laos, Vietnam. (*Franz Steindachner, an Austrian herpetologist).

     Palea steindachneri exhibits sexual dimorphism. Females of this freshwater turtle reach up to 44.5 cm (17.5 inches) in straight carapace length, while males only reach up to 36 cm (14 inches). However, males have a longer tail than the females.

BAN TU THU
08 /2022