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 itself 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.