TEXT 5. SHELLS

Many kinds of animals without backbones have shells. Most of these animals live in water. They build their shells out of lime from the water. An animal's shell grows as the animal grows.

The shells of some animals are all in one piece. The shells of others are made of two parts hinged together.

Many of these one-piece shells come from snails. Snail shells are probably the shells people know best. There are water snails and land snails. All snail shells are twisted. Some of them are twisted in one direction, some in the opposite direction. Because of the way they are twisted, snail shells are called "right-handed" or "left-handed". The left-handed whelk¹ makes one of the left-handed shells. Most of them are right-handed. Probably the biggest of the one-piece shells is the shell of the queen conch² (KONGK). This shell has a beautiful pearly pink lining. When a person holds a queen conch shell to his ear, he hears a roar like the roar of the sea. Many people think that they are really hearing the sea, but of course they are not. The least little sound outside will be magnified into a roar inside the big twisted shell.

Among the animals with two-piece shells are the oysters, mussels³, scallops⁴, and clams⁵. The animals with two-piece shells are often called bivalves⁶. This name comes from the Latin and means "two doors".

Many people collect shells for a hobby. The names they give the shells may have nothing to do with the animals that made them. Instead they tell how the shell looks. There is no way of telling from the name "angel wing", for instance, that the animal that makes this beautiful shell is really a kind of clam.

Shells make a good protection for the animals that have them. They are also useful to humans. Many buttons and beads are made of shells. Shells are broken up and used as food for some animals. Chickens, for instance, are fed oyster shells. Grown-up shells are sometimes put on soil to keep it from getting sour.

For hundreds of millions of years animals with shells have lived in the sea. Billions of these shells have sunk to the bottom of the sea and have formed thick layers that have become solid limestone⁷.

Questions

1) What kind of shells do people know best?

2) What are snail shells called because of the way they are twisted?

3) What is the biggest of the one-piece shells?

4) What do we call the animals with two-piece shells?

5) Are shells useful to people?

Notes

1. whelk - рубец

2. conch - раковина

3. mussel - двустворчатая ракушка

4. scallop - гребешок, створчатая раковина

5. clam - съедобный морской моллюск

6. bivalve - двустворчатый

7. limestone - известняк