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will not stretch. Then how do these little creatures grow? We see small
Shrimps and large ones, so grow they must, in some way.

They are of the same family--the _crustacea_--as the crab; and they grow
in much the same way. The hard covering gets too tight for the body
inside it. Then it splits across the back. After much wriggling, the
Shrimp appears in a new soft skin. While the skin is still soft the
Shrimp grows very quickly. Crustaceans have a funny way of growing, have
they not? Instead of growing evenly, little by little, they grow by
"fits and starts," a great deal in a few hours and then not at all.

Besides being good food for us, and for the fish, Shrimps and Prawns
have another use. They are scavengers. They pick to pieces and eat the
vegetable and animal stuff which floats in the sea. Before it can decay
and become poisonous, these useful creatures use it up as food. Great
numbers of Shrimps and Prawns are caught for our markets. Some are
caught by men who push a small net over the sands near shore, but most
are caught by the _shrimp-trawl_, a large net cast from a small sailing
vessel.

The rocks, and the wooden piles of the pier, are often covered with the
hard shells known as Barnacles, or Acorn Shells. If you slip on them
with bare feet their sharp edges cut you. Each Acorn Shell is a little
house. Have you ever caught a glimpse of the animal living inside?

If you will look very carefully, you will see that the Acorn Shell is
made of three-sided pieces, closely joined. There is a little door at
the top, kept tightly closed until the tide comes up and covers the
rocks. Then watch, and you will see a bunch of tiny feathers appear
through a slit in the door. This means that the animal is hungry, and
has put its twelve legs out of doors to catch a dinner!

This is strange, but true! The Barnacle is always upside down in its
home, and its twelve feathery legs are thrust out of the door at the
top. They make a fine net, in which minute animals are caught and
brought into the mouth below. This funny creature actually kicks its
food into its mouth! If you own a magnifying glass, you can see this for
yourself at the seaside.

You will not be able to see the mouth, however, which is inside the
shell. It is fitted with moving parts, and feelers, like the mouth of a
crab. Also, the Barnacle has a good set of teeth to grind its food. It
has no real eyes, having no use for them. Of what use are eyes to an