The Yangtze giant softshell turtle (Rafetus swinhoei), also known commonly as the Red River giant softshell turtle, the Shanghai softshell turtle, the speckled softshell turtle, and Swinhoe's softshell turtle, is an extremely rare species of turtle in the family Trionychidae. It may be the largest living freshwater turtle in the world. The species is native to eastern and southern China and northern Vietnam. With a known population of only three individuals, and with the last females dying out, this species is considered functionally extinct.
Description
The Yangtze giant softshell turtle is noted for its deep head with a pig-like snout and dorsally placed eyes. This critically endangered species holds the title of being the largest freshwater turtle in the world. Although hard to compare due to the extremely small number of remaining specimens, its average and maximum sizes seem to exceed other large freshwater turtles such as alligator snapping turtles and related giant softshells such as other Rafetus and Pelochelys species. It measures over in overall length and to in width, and can easily weigh up to . The average size of large turtle specimens (i.e. turtles weighing over ) that could be collected in the Yangtze River per one study was , although not all specimens were definitively identified as Rafetus. Its carapace, or shell, can grow larger than , with the largest shell that could be found having measured in length.<ref>Le DM, Pritchard P (2009). "Genetic variability of the critically endangered softshell turtle, Rafetus swinhoei: a preliminary report". pp. 84-92. In: Ngo DC, Ta HT, Le NN, Hoang XQ, Vo VP, Nguyen VS, Nguyen VT, Le TT, Tran QD (eds.) (2009). Proceedings of the First National Science Workshop on Amphibians and Reptiles in Vietnam. Hue: Hue University Press.</ref> However, along the curve carapace lengths of up to have been reported and it is possible for the largest specimens (largely reported in Vietnam) to have weighed up . Its head can measure over in length and in width. The male is generally smaller than the female and has a longer, larger tail.
Known individuals
Only two or three living individuals are known: one in China (captive) and one or two in Vietnam (wild). Following the deaths of a wild individual in Vietnam in January 2016 and a captive individual in China in 2019, the species is listed as Critically Endangered in the IUCN Red List. The female of the last breeding pair died at Suzhou Zoo in China in April 2019. A wild female was discovered in Vietnam on October 22, 2020, and another individual is believed to have been sighted in the same area; however, this last wild female was found dead in early 2023.
Geographic range
The Yangtze giant softshell turtle has been known to inhabit the Yangtze River and Lake Tai, situated on the border of Jiangsu and Zhejiang Provinces, in eastern China, and Gejiu, Yuanyang, Jianshui and Honghe in Yunnan Province in southern China.
A specimen at the Beijing Zoo died in 2005, and another one at the Shanghai Zoo died in 2006; both of them were caught at Gejiu in the 1970s. In 1999, 2000, and 2005, turtles re-emerged from Hoan Kiem Lake in Hanoi and were seen by a large audience and caught on film. Only a single turtle was believed to be left in the lake. In April 2011, it was captured because it had open sores (possibly due to refuse and pollution in the lake, injuries from fishing hooks or other turtles) that needed to be treated. It was reported dead in January 2016. On April 13, 2019, the only female turtle in Suzhou Zoo was reported dead shortly after the latest fertilization process. In 2020, another female was found in Vietnam's Dong Mo Lake, and it is believed that another individual is also living at the lake. They may also be still another individual in nearby Xuan Khanh Lake. The Dong Mo specimen died in April 2023, leaving the turtles at Suzhou Zoo and Xuan Khanh Lake as the last two recognized surviving specimens of this species.
Ecology and behaviour
Diet
R. swinhoei eats fish, crabs, snails, water hyacinth, frogs, and "green rice leaves".
Reproduction
The Yangtze giant softshell turtle may lay from 20 to more than 80 eggs. It nests at night and during the morning.