1. PEA CRAB (life-size).
2. CRAB CATERPILLAR (enlarged).3. CRAB CHRYSALIDS (enlarged).
2A. ” ” (life-size).3A. ” ” (life-size).
The word “megalopa” means “a creature with big eyes,” and it is given to the crab chrysalis because it has eyes which are enormously big in proportion to the size of the head. They are set on long footstalks, which project on either side, so that the head looks rather like a hammer. Then the long curved horns which the zoea had are to be seen no longer, and the carapace is shaped much more like that of the perfect animal, while the great claws begin to show, and the legs increase in length. The tail, however, is still quite free, like that of a lobster, and the little animal still swims by turning somersaults in the water, and lives on the same tiny scraps of decaying matter on which it fed as a zoea. After a few weeks it throws off its skin once more, and appears in the world as a perfect crab.
If you go down among the rocks when the tide is out, and hunt about in the pools, you may often find the shell of a whelk in which a small crab is living, with one of his great claws carefully guarding the entrance. This is a Hermit Crab, and a very curious little creature he is. For, in the first place, his long tail is quite free, like that of a lobster, instead of being fastened down to the lower surface of his body; and in the second place, it is quite soft, without any shelly covering at all. His body and limbs are covered with armour, just like those of other crabs, but his tail has none at all.
The consequence is that the hermit crab always has to take the very greatest care of his tail. He is so dreadfully afraid that one of his many enemies will come up behind and give it a nip when he isn’t looking! So he protects it by tucking it away into the empty shell of a whelk. He never leaves this shell, but drags it about with him wherever he goes. And if you take hold of him and try to pull him out, you will find that you cannot do so without injuring him very badly. For at the end of his tail he has a pair of strong pincer-like organs, with which he holds on so firmly that it is very difficult indeed to make him let go.
Indeed, the only way to get a hermit crab out of his dwelling is to put him, shell and all, into the spreading arms of a big sea anemone. That frightens him almost out of his wits, for the arms of the anemone at once come closing in, and he knows quite well that if he stays where he is he will very soon be swallowed. So he skips out of the shell and scampers away as fast as he possibly can, leaving the empty shell in the anemone’s clutches.