Angie Ray, age 11, of Morganton, N.C., for her question:
HOW MANY KINDS OF SNAILS ARE THERE?
Birds and fish eat lots of snails. And some people eat them, too. They consider the Helix, one type of garden snail which is also called escargot, a great delicacy. Another snail, called the turban and found in Australia, is also useful: His pearly shell is used to make shirt buttons. But for the most part, the snail has nothing to do except help to keep up his share in the balance of nature.
You'll find snails almost everywhere on earth. They live on deserts and in forests. Some types are at home on mountaintops while others pick oceans, rivers and ponds as the locations for their homes.
And how many different kinds of snails are there? Think of a large number. If you said there are more than 80,000 different kinds of snails on earth, you are right.
Some snails are so small that one of them would have space left over if he were standing on the head of a pin. His largest cousin measures more than two feet in length.
Snails eat a wide variety of food. Some that live on land eat rotting plants. Some of the sea snails eat seaweeds, while others eat ocean animals. One type of ocean snail is a parasite and lives only on starfish or inside living sea animals called corals.
Land snails have both female and male sex organs in the same animal, while most water snails are either male or female.
Most snails have soft bodies and are covered with coiled shells. They crawl along on strong muscular organs behind protruding feelers, bulging eyes and mouthfuls of tiny teeth.
The snail's muscular organ, called a foot, is used to push the animal forward as the muscle moves in a backward, wave like motion. As the land snail moves along, he pours out a sticky liquid called mucus. This material acts as a path and makes the traveling easy. Beetles and ants, enemies of the snail, sometimes get caught in the mucus.
Largest single group of snails are the saltwater or marine snails. There are about 55,000 different kinds. You'll find some along the seashore, while others live in the deepest parts of the oceans. Most of the marine snails have gills. Many have extremely colorful shells that include lids called operculum. These lids seal off the animal whenever it draws itself into its shell.
During dry weather, many types of land snails seal themselves inside their shells by building a doorlike covering with dried mucus. The snail will rest in this inactive condition until the dry spell ends.
Another large group of snails are those found in fresh water. About 5,000 are included in this classification. Some have lungs and must come to the surface of the water to breathe oxygen in the air. Others have gills which take in oxygen from the water.
One type of freshwater snail found in the tropics carries a disease called schistosomiasis. It causes thousands of deaths each year.