THE HERMIT CRAB

Auckland Star, Volume LXVIII, Issue 108, 8 May 1937, Page 10 (Supplement)

THE HERMIT CRAB

He Has Some Useful

Messmates

One sometimes finds remarkable instances of companionship among animals (writes Mr. W. G. White, F.C.S.). For instance, the hermit crab is a member of the crab tribe. He has a tail like a lobster, except that he has no hard shell to cover it, and so, lest it should be suddenly bitten off by a fish looking for a daint*, tender piece of food for a meal, he takes possession of an empty whelk shell and tucks himself in backwards, leaving only his head and front claws sticking out. In this condition he nearly always has two companions. One is a tall column of flesh growing on the shell, which looks like a seaplant with a flower on the top. It is called a sea anemone, but it is not really a plant; it is one of the lowest forms of animal life. The feathery-looking tip is not a blossom, but the tentacles, or slender arms, by means of which it sucks its food out of the water. The other companion is a richly coloured, beautiful-looking sea worm, which occupies the cavity in the shell behind the crab, near the point. These three! messmates are very useful to one another. When the hermit crab moves from place to place he takes his house with him, and so he not only finds a new feeding ground for himself, but he gives the anemone a change of water in which to grope for its nourishment. When the crab finds food and settles to enjoy it, the worm creeps out ov.er his back, and is allowed to share it. The worm is in no sense a parasite, for it has work to do. It keeps the inside of the shell clean. It acts the part of a scavenger, therefore, to its host. When the hermit crab has finished his meal he likes to sleep, so he backs into the shell as far as he can and. drawing his largest claw across the opening, proceeds to doze. The sea anemone, which is sticking straight up in the water, looks just as if it were a plant, and. therefore, the notice of hungry fishes is not drawn to the shell. Even if any fish should venture near to investigate, he would soon swim away in disgust, for the anemone is covered by slime, which has an odour horrible enough to frighten away any fish, however inquisitive.