Jody Ehalt, age 11, of Grand Rapids, Minn., for her question:
HOW DO TURTLES HEAR?
Turtles are reptiles and they are cold blooded that is, their body temperatures stay about the same as the temperature of the air or water that surrounds them. There are about 240 different species living today, with about 50 of them found in North America above Mexico. Some live on land while others spend their entire lives in water.
Almost all species of turtles can pull their heads, legs and tails into their shells for protection. The shell serves much like a suit of armor.
Turtles have extremely well developed senses of touch and sight. Tests have also shown that they have a good sense of smell and can also hear very well, especially sounds that are made near them.
Turtles have, as part of their outer ears, eardrums which are called tympanic membranes. In addition, they have middle and inner ears. Tests have shown that a turtle can hear low pitched sounds just about as well as a human being can.
Most turtles have heads that are covered with hard scales. They have no teeth, but they have beaks with hard, sharp edges that they use to cut food. Most turtles have very powerful jaws which they can also use to tear food and captured prey.
Most turtles eat both animals and plants. A few type of turtles, including the green turtles and the tortoises, feed almost entirely on plants. A number of freshwater types, such as the map turtles and the soft shelled turtles, eat chiefly animals.
All turtles, including those living in the oceans or in fresh water, lay their eggs on land. The female digs a hole in the ground with her back feet when she's ready to lay her eggs. The hole is then covered with either soil, sand or rotting plant matter. The number of eggs will vary from the African pancake tortoise who lays only one at a time to the sea turtle who may lay as many as 200 eggs at a time.
Most turtles lay their eggs between late spring and late autumn, and some types lay eggs more than once during this period. The warm sun hatches the eggs. Then the babies dig their way out of the ground and start looking for food. They're on their own right from the moment they're born.
There are seven main groups of turtles: mud and musk turtles; pond and marsh turtles; sea turtles; side necked turtles; snapping turtles; soft shelled turtles; and tortoises.
There are about 40 species of tortoises, with three living in the United States. Tortoises live only on land. In this country you'll find the desert tortoise in the Southwest, the gopher tortoise in the Southeast and the Texas tortoise in the scrub forests of southern Texas.