The most famous tortoises, as well as the largest, are those found in the Galapagos Islands. Individuals among these giant land tortoises have weighed four and five hundred pounds. At one time there were great numbers of land tortoises living on the volcanic Galapagos. However during the whaling days in the South Pacific men discovered that they could be used for meat. Thousands of them were packed aboard whaling vessels and killed for food. The tortoises could go for long periods without food and water. They were slaughtered as needed to provide the crew members with fresh meat. After whaling had stopped, because of the discovery of petroleum, fishermen still continued to kill large numbers of these turtles for the oil that could be secured from their bodies.
Today the Galapagos tortoises are in danger of being totally exterminated. They apparently lay very few eggs and these as well as the young turtles are destroyed by the rats, wild dogs, cats, and other animals which man has introduced into these islands. Some of them can be seen in zoos, but they have seldom bred in captivity.
The desert tortoise, found in western American deserts, is related to the Galapagos tortoise but it is much smaller, only about ten inches long. These desert tortoises, like their larger relatives, eat cacti. They are not active during the heat of the day, but rest in underground hiding places. When the temperature falls in the evening they come out to feed. During mating season the males often have battles over the females. They try to tip each other over and one is sometimes successful. With a great deal of effort a tortoise can succeed in getting back oh its feet, but in the meantime the victor has gone off with the female.
Turtles which live in a completely different environment are the sea turtles. The largest of these is the leather back which may be six to eight feet long and weigh over a thousand pounds, although turtles of this size are rare. The green turtle, caught commercially for food, may weigh four hundred pounds.
Most sea turtles live in warm ocean waters. Their legs have become modified into flippers so that they can make rapid progress, sometimes reaching a speed of twenty miles through the water. They still need to breathe air and must come up to the surface at least every few hours. Sea turtles return to land to lay their eggs. The female laboriously crawls up on a sandy beach and digs a hole in which she may deposit as many as one hundred eggs. Then she covers them with sand, and goes back to the sea.
The eggs hatch from one to three months later and the tiny young turtles get down to sea as fast as they can. Many young are lost to predators such as gulls, ospreys and large fish. In some regions turtle eggs are considered to be a great delicacy, and people dig them up. Because of the decreasing numbers of sea turtles, an effort is being made to protect them, and it is unlawful in many places to disturb their nests.
There are also turtles which live in fresh water. One of the most fascinating of these is the alligator snapper, which lives in the southern part of the United States. The alligator snapper may measure more than two feet in length and may weigh one hundred and fifty pounds. It spends its life almost entirely in the water; only the female comes out to lay her eggs on land.
The alligator napper has its own built- in fish lure—a projection on the front of its tongue which looks like a wiggling worm. Any fish that investigates this lure is apt to become food for the turtle. Turtles are the oldest living order of reptiles. Their ancestors were on earth two million years ago, even before the dinosaurs, and present-day turtles have not changed very much since then. It is thought that their shell has aided their survival.
All of them lay eggs and all of them have shells. This shell, covered with horny plates in most species and with leathery skin in others, is the turtle’s defence against its enemies. Because of this heavy shell, a turtle moves slowly on land. A tortoise can travel about one quarter of a mile in an hour, if it does not decide to rest on the way. Turtles are cold-blooded, which means that their body temperature is regulated by the temperature of the air. For this reason they are not found in very cold climates, and must hibernate during the winter months in temperate regions.
Those that live in hot climates cannot stay in the sun—they would die if exposed for any length of time to a temperature above 110° F.—and must hide in shaded or cool spots during the day. Yet with luck, turtles can live to be older than most other animals. There is a record of one tortoise in captivity that lived to be one hundred and fifty years old. In the United States the word turtle is usually used to refer to those species which live largely in water; the word tortoise to those species which live entirely on land. There are about two hundred species of turtles found in the world today.
Turtles Pictures
