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Afro-American River Turtles: Podocnemididae - South American River Turtle (podocnemis Expansa): Species Account

eggs nesting sometimes conservation

Physical characteristics: Also known as the arrau or tartaruga, the South American river turtle sometimes is described as "giant" because it is so large. The upper shell can measure more than 3.5 feet (1 meter) in length. The carapace is rather flat and a bit wider at the rear than it is at the front. It is typically dark brown, but in spots it may be worn away to a paler, almost orange color in older turtles. The head is dark on top and down the cheeks but pale yellowish-tan on the bottom and on the neck. Two barbels hang from its chin. Young Also known as the arrau or tartaruga, the South American river turtle sometimes is described as "giant" because it is so large. The upper shell can measure more than 3.5 feet (1 meter) in length. (Illustration by Jonathan Higgins. Reproduced by permission.) turtles have a more patterned head with yellow blotches outlined or spotted in black.


Geographic range: These turtles live in northern South America.


Habitat: These freshwater turtles live in large river branches in the Orinoco and Amazon river systems of northern South America. If the water rises high enough and overflows into areas next to the rivers, they may move into these flooded areas, too.


Diet: This species eats plants, insects, and sponges, but it prefers the fruits of riverside trees.


Behavior and reproduction: Nesting begins shortly after the rainy season ends. During the nesting period, which may last ten to sixty days, the female travels upstream or downstream to reach a nesting site, which she shares with other females. Late at night the females climb onto a sandbar, and each one uses both her front and hind legs to dig a hole more than 1 yard (1 meter) around and 1.5 feet (0.5 meters) deep. At the bottom of the hole, the female uses only her hind legs to continue digging another pit, where she lays her eggs. Unlike other members of the family, which lay oblong eggs, the South American river turtle lays round eggs. Most of the eggs are about 1.6 inches (4 centimeters) across, but one or two may have a diameter twice that size. A typical nest holds about eighty eggs, but it contain as few as forty-eight eggs or as many as 156 eggs.

The females make only one nest per year. After laying her eggs, the female covers up at least the bottom hole, containing the eggs, and sometimes also the hole above it. The eggs hatch in about a month and a half; within a couple of days after hatching, the young make their way out of the nest. The sex of the hatchlings, or young turtles, depends on the temperature of the nest: extremely warm or very cool temperatures produce females, whereas temperatures that are more moderate, or mild, produce males. Scientists know few details about other activities of these large turtles.


South American river turtles and people Although it is now illegal to do so, some people still hunt and kill adults and sometimes even baby turtles for their meat and collect eggs for the oil they contain.


Conservation status The U.S. Fish and Wildlife Service lists this turtle as Endangered, which means that it is facing a risk of extinction in the wild. The World Conservation Union (IUCN) lists it as Lower Risk/Conservation Dependent, which means that its survival relies on sound conservation efforts. These listings result from the fact that humans have killed adults and destroyed their eggs over many decades. The turtle's range became smaller and smaller as the hunting and collecting continued. Efforts are under way to protect their nesting areas and to prevent further collecting of turtles or their eggs. ∎

FOR MORE INFORMATION

Books:

Burnie, David, and Don E. Wilson, eds. Animal: The Definitive Visual Guide to the World's Wildlife. London: Dorling Kindersley, 2001.

Web sites:

Pecor, Keith. "Pelomedusidae." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Pelomedusidae.html (accessed on August 6, 2004).

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