[Illustration: FIG. 151.--Crabs that form galls on corals: _a_, _Cryptochirus_ (male); _b_, _Coralliodytes_ (female); _c_, _Hapalocarcinus marsupialis_ (female), that carries its young in a sac or marsupium.] Crabs select singular places for homes. One lives in the sea cucumber; others live in corals, which appear to grow over them, forming a gall (Fig. 151). The little oyster crab found in bivalves is a familiar form. But perhaps the most remarkable home for a crab was the bowl of an old tobacco pipe in which a crab I once owned ensconced itself. This was a hermit crab (Fig. 152). The hermits differ from other crabs in having a long, but soft and totally unprotected tail or abdomen, to preserve which they enter empty shells and drag them about wherever they go. The hermits occur in great variety, and there are marine hermits and land hermits. On the Florida Reef they are found in myriads; every shell alongshore conceals a baby hermit; and almost every nook or cranny affords concealment for a score of them, their red and blue claws forming an attractive contrast to the shell. [Illustration: FIG. 152.--Hermit crab.] The hermit referred to was first found in a pearly shell and placed in the office, but finally it outgrew this and deserted it for the pipe which some workmen had left on the floor. Every day this old pipe would be clanked and dragged about the room, and once in a while the crab would drag it up a table leg, so reaching the tablecloth and then the table top, where it drank out of a saucer left for the purpose. Later a marine hermit was found in a pipe bowl, proudly dragging the grotesque house about. Anything of this kind would be used by the hermits. One was found in the opening of a spool; and this would roll over and over, carrying the hermit with it. Another took possession of a reed. Among deep-sea sponges the hermits are seen occupying holes in the sponges. A community of hermits is a laughable sight. They are very pugilistic, and are always fighting. When a hermit outgrows its shell and begins to feel uncomfortable it endeavors to turn out some comrade that has a larger shell, and in the battle arms and claws are often lost. This, however, is not serious, as they grow again. When the hermit finds an empty shell it thrusts in its claws and antennæ, probing it in every direction to see that it is not occupied. When satisfied, it jerks itself out of its own shell, and with the greatest rapidity whisks its soft unprotected body into the new house, where, if it fits, it remains. The shell, when large, is not carried, but dragged about, and when the crab is alarmed or startled it darts backward into the shell, where its large claw and the others constitute almost as good a door as the real operculum of shells. The largest hermits are the marine forms, which enter the large conch shells and drag them about. These hermits are a brilliant red in color. Their claws are very rough.