Friday, December 05, 2008

Tortoises and Turtles

Tortoises and Turtles are unique among animals, having their whole bodies enclosed in a bony box. This is built from the rib cage which grows and joins up outside the limbs. The earliest tortoise show separate ribs but even these are already flattened as if about to join together. This peculiarity goes back even before the dinosaurs, so that chelonians (the name of the order to which tortoises and turtles belong are the oldest group of reptiles. They even have the oldest individuals on earth today- the giant tortoises which can live to a hundred and fifty years or more. Chelonians are of three kinds-tortoises, turtles and terrapins. Tortoises are land reptiles with domed shells and stumpy legs. They move about clumsily and feed mostly on plants and fruit. The largest are the giant tortoises of the Galapagos Islands in the Pacific, and the Aldabra Islands in the Indian Ocean. They can weigh up to 550 kilograms and measure almost two meters in length. Tortoises sold in shops as pets come from the Mediterranean countries, and have been known to live up to a hundred years. Eggs are laid in the ground and left to hatch in the sun.

Turtles are sea-going chelonians, with flatter shells than tortoises and more paddle – like feet for swimming. At night the females come ashore on some lonely tropical beach where there is sand. They dig pits in which up to 150 eggs may be laid. These are covered up and the mother then returns to the sea. Later the babies hatch out, struggle to the surface, then make as fast as they can for the water. On the way many are caught by the waiting sea-birds. Because turtles are also caught for food and their eggs dug up, some are now becoming rare. One or two countries do protect turtles by fencing off some of the beaches where they lay their eggs, later collecting the young and taking them out to sea where they will be safe to grow up. The largest turtles, up to 400 kilograms and one and a half meters long, is the Leathery Turtle. The Green Turtle is the species usually caught for making turtle soup, and the Hawksbill Turtle for its shell, called tortoiseshell.

Terrapin is an American Indian name for freshwater tortoises which swim in rivers and marshes, catching fish and water animals. They spend hours basking in the sun at the waterside, but dive in at any sign of danger.

No comments: