About Turtles

History of the turtle -

Turtles existed 200 million years ago, at the time of the earliest dinosaurs; these early turtles could not retract their necks. Many of the living families of turtles existed in the Cretaceous period and have undergone very little change since then. Turtles are found throughout most of the temperate and tropical world and in the open ocean; of the 270 known species, 42% are rare or threatened with extinction. About 45 species are found in the U.S. and Canada.

Life of a Turtle -

Most of a turtle's growth occurs during the animal's first 5 to 10 years. The turtle continues to grow after reaching this age, but at a much slower rate. It can take 10 to 30 years for some turtles to reach sexual maturity.

All turtles, including sea and freshwater species, lay their eggs on land. Young turtles hatch from eggs, which are fertilized within the female's body. One mating can result in the fertilization of all the eggs of a female for several years. Most species lay their eggs between late spring and late autumn, and some lay eggs more than once during this period. Among most species, the female digs a hole in the ground with her back feet to lay her eggs and covers them with soil, sand, or rotting plant matter. The warmth of the sun hatches the eggs. The temperature at which the eggs are incubated also determines the sex of the hatchlings. Newly hatched turtles must dig their way to the surface of the ground, obtain food, and protect themselves all on their own once born.

Most kinds of turtles eat both animals and plants. The organisms eaten by a turtle vary among the species. A few kinds of turtles, including green turtles and tortoises, feed almost entirely on plants. Some turtles feed exclusively on snails or crabs and other crustacean.

Types of Turtles -

Turtles are classified in 12 families. There are seven main groups of turtles: (1) the mud and musk turtles, (2) the pond and marsh turtles, (3) sea turtles, (4) the side-necked turtles, (5) snapping turtles, (6) the soft-shelled turtles, and (7) tortoises.

Turtles, like all reptiles, are cold-blooded—that is, their body temperature stays about the same as the temperature of the surrounding air or water. Turtles cannot remain active in cold weather. So they cannot live in regions that are cold throughout the year. Some species hibernate in soil or the bottom of a body of water. Turtles live almost everywhere—in deserts, forests, grasslands, lakes, marshes, ponds, rivers, and the sea.

Turtle shells are commonly brown, black, or olive green. In some species, shells may have red, orange, yellow, or gray markings. These markings commonly appear as spots, lines, or irregular blotches.

For more info, check out the -World Turtle Data base http://emys.geo.orst.edu/

Sources:

Some text acquired from & copyright to: "Turtle," Microsoft® Encarta® Online Encyclopedia 2002
http://encarta.msn.com © 1997-2002 Microsoft Corporation. All Rights Reserved. Used for educational purposes only.

Some text from and copyright to: Bartleby.com, Inc. http://www.bartleby.com, The Columbia Encyclopedia, Sixth Edition. Copyright © 2002 Columbia University Press. All Rights Reserved. Used for educational purposes only.