Arrau River Turtle
Scientific name:, Podocnemis expansa
Order: Pleurodira
Family: Pelomedusidae (6 Podocnemis species)
Also Known As: Giant South American river turtle
Description: To 31 inches. Largest species of the genus. Longitudinal groove between eyes. Usually two barbels on chin. Upper jaw squared off at the tip. Front legs with five claws; hind legs with four claws. Row of enlarged scales on the back of each limb. Carapace broad, flat, much wider posteriorly than anteriorly.
Brown, olive, or black above. Head commonly with yellow, orange, or red markings. Plastron yellow, grey or brown. Large females have very wide and flattened shells, sometimes with a shallow groove along the midline, and usually extensive areas of black on the plastron.
Males are smaller than females. Juveniles have a head with large, lemon-yellow spots and yellow spots encircling black dots on the dorsal. Head spots darken and disappear with age. Strong keel on carapace.
Distribution: Northern South America in jungle rivers and Orinoco and Amazon river drainages.
Breeding: Details unknown.
Nesting: During dry season (September to November in Brazil, March to April in Venezuela), migrate to nesting site and concentrate on beaches. Females bask; this may play a role in egg maturation.
Begin nesting 2 to 3 weeks after the onset of basking, often at night. Dig nest 3 feet in diameter, 24 inches deep, with an egg cavity 12 inches deep and 10 inches wide. Female irrigates the nest with water from her cloaca to help the sand maintain its shape.
50-150 (average approximately 80) spherical, soft-shelled eggs are laid and covered with sand. Female may or may not fill entire nest with sand. Eggs are approximately 11/2 inches in diameter and incubate approximately 45 days.
Hatchlings are 2 inches at birth, and usually emerge at night or early in the morning to avoid the intense mid-day heat, then head directly to water. They have a uniform brown carapace.
Diet: Omnivorous, but herbivorous when mature. Eat aquatic vegetation and fruit. Fast during the dry season.
References
The Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium. Fritz Jurgen Obst, Dr. Klaus Richter, and Dr. Udo Jacob. Translated by U.E. Friese. Neptune City, New Jersey: T.F.H. Publications, Inc., 1988.
Grzimek's Animal Life Encyclopedia. Volume 6: Reptiles. Dr. H.C. Bernhard Grzimek, Editor. New York: Van Nostrand Reinhold Company, 1975.
Encyclopedia of Reptiles and Amphibians. Dr. Tim Halliday and Dr. Kraig Adler, Editors. New York: Equinox (Oxford) Ltd., 1986.
Encyclopedia of Turtles. Dr. Peter C.H. Pritchard. Neptune, New Jersey: T.F.H. Publications, Inc., 1979.
