Thursday, Feb. 26, 2004
* Japanese name: Ishigame
* Scientific name:Mauremys japonica
* Description:Also known as the stone turtle, the pond turtle is semiaquatic and a strong swimmer. It has a yellowish-brown carapace (shell) and an olive-brown head. Females are bigger than males, growing up to 21 cm long (carapace length), with males only 14 cm. But males have longer tails. Turtles of both sexes have a single keel (ridge) on the shell, which is serrated at the back edge. Pond turtles have orange lines on the sides of their legs.
* Where to find them: Honshu, Shikoku and Kyushu, in cool streams and ponds in the mountains, often in cold, fast-flowing water. They also live in canals and irrigation ditches for rice fields. In winter, pond turtles hibernate on the bottoms of streams and ponds. If disturbed, they may produce a foul-smelling secretion as a deterrent. Once common in Japan, their numbers have fallen dramatically recently, due (experts say) to competition from foreign turtle species that have escaped from captivity. One to three times a year, females lay four to 10 eggs in dry underground burrows, and if the eggs are not eaten by raccoon dogs, weasels or snakes, they hatch in two to three months. Mating (usually underwater) can be aggressive, and females may sustain deep bites to the head and neck.
* Food:The pond turtle's diet is varied, and includes water insects and larvae, mollusks, tadpoles, frogs, filamentous algae, earthworms, small amphibians and tadpoles.
* Special features:All animals that hibernate in winter reduce their metabolism so they can survive without eating for long periods, but pond turtles have another particularly cool trick. They hibernate underwater, at the bottom of their pond or river. Their body temperature and heart rate fall (to a single, sluggish beat every few minutes), and they stop breathing through the mouth. But they can't do without oxygen for the entire winter, so they extract what they need from the water, using specialized cells in their tails.