Turtles belong to the order (order is a
level of classification used by scientists) Testudines (sometimes
called Chelonia), they are in the class Repitlia, because they are
reptiles. Reptiles are cold-blooded. This means that the body
temperature depends on the temperature of their environment. There are
about 250 species of turtles, (which is quite a lot, considering that
there are only about 3 million species total).
These species are divided into about 12 families.
Turtles can be found on every continent,
except Antarctica. They can live in a variety of habithats. Some
turtles live in the sea, while others live in ponds, rivers or even in
the hottest deserts in the world.
Turtles have exoskeletons. An
exoskeleton is like the bone structure, only it is on the outside of
the body. The exoskeleton is also known as a shell. The shell is fused
to the bacbone and to the ribs, and are covered with large plates, or skutes.
The top of the shell is domed and known as the carapace. The
bottom part is flat, called the plastron.
The shell of a turtle can be either hard
or soft. Some are large and some are very small. Snapping turtles have
small shells and sea turtles have very soft shells. In fact, most
turtles that live in the water have soft shells; some are even called "
leatherback" for their sof shells. Turtles that live on the land and
tortoises usually have very hard shells. Turtles with soft shells lack
horny plates, but do have leathery skin.
Turtles are over 200 million years old.
This means that turtles were around when the dinosaurs were! Fossils
have been found to prove this.
All turtles are tootheless, but have a
sharp-edged beak so that they can eat. This works ver well, especially
for the Alliga
tor Snapping Turtle, who can bite off a human finger in a single bite.
Turtles also have a good sense of
eyesight and smell. They can be sexually distinguished by their
plastrons. Males have concave plastrons, while females have flat ones.