The mother Lobster carries as many as thirty thousand eggs under her body! Needless to say, a very, very few of this enormous family survive the dangers of the sea. The rule there is—“Eat and be eaten!”.
1. What is a Crab larva like?
2. Give the names of four crustaceans.
3. Why does the Crab have to change its shell?
4. Why does it hide away at that time?
5. Of what use are Shore Crabs?
6. How are Lobsters caught?
[Illustration: THE LOBSTER.]
SHRIMPS, PRAWNS AND BARNACLES.
In nearly every shore-pool you may see Shrimps and Prawns darting out of sight, and, for every one you see, there are many more hidden away. These delicate, transparent, lively creatures are not much like the boiled Shrimps and Prawns of the fish-shop.
They are the prey of so many fish, crabs, and birds, that they have learnt to “make themselves scarce.” Have you ever watched them in a glass tank, or aquarium? If so, you will know that it is not easy to see them. In the shore-pools it is harder still.
Some are swaying about in the still, clear water, moving their long feelers from side to side. Others have burrowed into the sand. In doing this, they raise a sandy cloud, which settles on them and hides them. To catch some, you must use a “shrimp-net,” for they can dart 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.