One of the most extraordinary crustaceans is this, which is found in many of the islands in the Indian Ocean. It is like the hermit-crabs in some ways, but the tail is covered with shelly plates, just like the rest of the body; and instead of living in shells in the sea, it lives in deep burrows on dry land.
But the oddest thing of all with regard to this crab is its food. What do you think it feeds upon? Cocoanuts! That seems impossible, doesn't it? One would imagine that the crab could never get the nuts open. But it manages in this way: First of all, it pulls away the fibers from that end of the nut at which the three eyeholes are situated. With one of its stout claws it then hammers away at one of these till it breaks its way through. And finally, after allowing the milk to run away, it pokes its hind claws, which are very slender indeed, through the opening and picks out the white fleshy part of the nut a little piece at a time.
It is said, too, that this crab sometimes opens a nut by poking the smaller joint of one of its claws into the hole, and then striking it over and over again upon a big stone.
The burrow of the robber-crab is rather a deep one, and is nearly always situated beneath the roots of a tree. And at the end of the burrow is a large chamber, in which the crab piles up a quantity of cocoanut fiber to serve as a bed.
Lobsters
Of course you know the lobster very well by sight; and perhaps you know that until it is boiled it is black, not red. But do you know how it swims? If so, you know that it has two different ways of swimming. When it is not in a hurry it swims slowly forward by means of its swimmerets, of which it has five pairs under the hinder part of its body. But if it is startled or alarmed it swims swiftly backward by means of its tail.
If you look at a lobster's tail, you will see that it is very broad and flat, and that on either side of it are two plates, which are quite as flat, and, if anything, are rather broader. So, when these are spread, the tail looks like a fan. And the animal swims by first stretching out its body almost straight, and then doubling it suddenly with all its force. As it does so, the tail and the tail-plates spread out, and act very much like a broad oar. And the result is that the lobster darts swiftly backward through the water. Shrimps and prawns swim in exactly the same way.
Lobsters are very quarrelsome creatures, and are constantly fighting; and it very often happens that in these battles they pull off one another's limbs. They seem to feel very little pain, however, from such an injury, and before very long new legs begin to grow in place of the old ones, so that in course of time the wounded creatures are as perfect as ever.
Sometimes lobsters will throw off their limbs when they are not attacked at all. They do so, for example, if they are suddenly frightened; and it is said that if a heavy gun is fired near the surface of the water, every lobster for a long way round will shed its great claws in alarm.
You will notice, on looking at a lobster, that one of the great claws is a good deal smaller than the other; and sometimes people think that this is a new claw which is growing in place of one that has been lost, and that it has not yet reached its full size. This, however, is a mistake, for one of the claws is always much bigger than the other; and the reason is that they are used for different purposes. The larger claw is intended as a weapon, and with this the lobster fights. But the smaller one is chiefly employed as a kind of anchor, by means of which the animal can cling to the weeds or rocks at the bottom of the sea.