Sinotaia quadrata

This species was described under the name Paludina quadrata by English conchologist William Henry Benson in 1842. It is now classified in the genus Sinotaia, although Chinese malacologists use the synonym Bellamya aeruginosa. Subspecies Two subspecies are recognised: • Sinotaia quadrata histrica (Gould, 1859) • Sinotaia quadrata quadrata (W. H. Benson, 1842) == Distribution and habitat==

Distribution This species is found in: • Japan • Northeast Thailand（Isan） • Vietnam • Italy (river Arno; non-native) • Argentina (Central Argentina; non-native) This species is also known from Upper Pleistocene of China. It is common in the Yangtze River and Yellow River basins. Habitat Sinotaia quadrata is found in rivers and lakes. usually in soft mud rich in organic matter. This species is not actively migrating, rather its dispersal appears to be caused passively by floods, animals (zoochory), and accidentally by humans. S. quadrata has been found to respond well to laboratory conditions with a water temperature of , pH 8 and a 1:4 ratio of sediment to water. ==Description==

S. quadrata breathes with gills. The right tentacle is thickened in the male but not the female. The diploid chromosome number of Sinotaia quadrata is 2n=16. The height of the shell is , with both sexes having identical shell dimensions. Adults snails have shell of greater height than width. The shells of newborn snails are long, and differ from those of adults in being wider than high. The snail including the shell has a weight of about . ==Ecology==

Feeding habits Sinotaia quadrata feeds on epiphytic algae. S. quadrata is a herbivorous deposit feeder. It consumes mainly epiphytic algae, but its diet also includes detritus, bacteria, and cyanobacteria such as Microcystis. cadmium, lead, ethylbenzene, 2,2',4,4'- tetrabromodiphenyl ether, tributyltin, microcystin, multi-walled carbon nanotubes, and 17β-estradiol. The species has a high sensitivity to copper exposure and could thus be used for monitoring of sediment toxicity caused by environmental copper pollution. Sinotaia quadrata snails from West Lake in Hanoi, Vietnam were found to be contaminated with copper, lead and zinc. The concentration of these elements in these snails exceeded standards of Food and Drug Administration and of Food Standards Australia New Zealand. Conservation The species' population trend is unknown, The genetic diversity of this species was found to be high in China. S. quadrata serves as an intermediate host for Angiostrongylus cantonensis and for Echinochasmus fujianensis. Predators of the species include the black carp Mylopharyngodon piceus; S. quadrata is one of the main food sources for this fish, making it important in the freshwater food chain. ==Human use==

Sinotaia quadrata is common animal food used in aquaculture to feed fish black carp in China. This species is also eaten by humans. In Isan, Thailand they are collected by hand or with a handnet from canals, swamps, ponds and flooded rice paddy fields during the rainy season. During the dry season, snails live under dried mud. Collectors use a spade to scrape the ground to find and catch them. Generally they are collected by both men and women. and constitutes one of the three predominant freshwater snails found in Chinese markets, as well as fish, poultry and livestock raising. The annual production of S. quadrata in Chao Lake in 2002 amounted to 28 084 t. Although harvesting pressure in China is high, the high genetic diversity suggests that the species is currently not negatively affected by it. ==References==