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(soft-shelled turtles), an order of freshwater turtles. The body and the flattened shell are covered with a soft skin instead of horny plates. The head ends in a soft proboscis, at the end of which are nostrils. The feet are broadly webbed. There are two families, the Carettochelyidae and the Trionychidae. The former has a single species, which lives in rivers in New Guinea. The Trionychidae have seven genera, embracing 22 species, which live in rivers of Asia, Africa, and North America.
Soft-shelled turtles are predators and speedy swimmers; they feed primarily on fish and mollusks. The auxiliary respiratory organs, which consist of bundles of hairy appendages of the mucous pharynx, play the role of gills and permit the turtles to remain under water up to 15 hours. The cutaneous coverings, which are richly supplied with blood vessels, ensure cutaneous respiration in the water and, partly, on land, a phenomenon that is extremely rare in reptiles. The females bury their white, spherical eggs, which have calcareous shells, on the shore. In Asia, soft-shelled turtles are commercially valuable; their flesh and eggs are used as food. In the USSR, the spiny soft-shelled turtle (Trionyx sinensis) is found in the lower course of the Amur River; the turtle is common in East Asia.
REFERENCESZhizn’ zhivotnykh, vol. 4, part 2. Moscow, 1969.
L. I. KHOZATSKII