across the
pool like arrows.

[Illustration: THE SHRIMP.]

Some are Shrimps, and some are Prawns; how can we tell the difference?
When they are boiled the answer is easy. All the Shrimps turn brown and
the Prawns red. (The red "Shrimps" are near relations of the Prawn.) To
tell a live Shrimp from a Prawn, look at the long pointed beak which
juts out from the front of the head. That of the Prawn is toothed, like
a little saw. If the beak is quite smooth its wearer is a Shrimp.

Until Prawns are grown up, they haunt the sandy shallows with their
cousins the Shrimps. But the larger Prawns live in deeper water. They
are generally caught in traps, as are their relatives, the crab and
lobster.

Now look closely at a Prawn, and try to find how it swims. Turn it
upside down. It has ten legs; and, under each of the horny rings of its
body, you can see a pair of little paddles. They are fringed with hairs.
When the Prawn or Shrimp is not in a hurry, he swims slowly but surely
with the little paddles, or "swimmerets." If any danger threatens, he
uses his tail, in this way:--It is made of five fringed plates, which,
as you can see, spread out or close up, like a fan. As he doubles up his
body, the plates spread themselves out. They strike the water with great
force, and so send the Prawn or Shrimp quickly _backwards_. As the body
becomes straight again, the fan closes, ready for another stroke. To
move quickly, the Shrimp or Prawn merely bends his body, then
straightens it. The tail thus becomes a strong oar, driving him
backwards with rapid jerks.

Look now at the Prawn's long, hair-like feelers. There are two pairs. On
one pair are the ears, a special kind of ear for hearing in water.

You will notice that the Shrimp's eyes are on the end of short stalks.
Each big eye is really a cluster of little eyes, rather like the
"compound eyes" of insects. If you lift up the horny shield behind the
head, you see a row of what look like curly feathers. These are the
breathing gills.

Shrimps carry their eggs about with them; no doubt you have often found
masses of eggs under the Shrimp's body. Each egg is fastened by a kind
of "glue," or else the rapid jerking of the mother Shrimp would soon
loosen the eggs and set them free.

The hard, shelly covering of the Shrimp and Prawn is like the armour of
the crab--it will not stretch in the least. The body is easily bent,
owing to the soft hinges between the hard rings. But the coat itse