A number of other animals are found associated with Hermit Crabs, without, as far as we can see, rendering any service in return for the house-room. The Whelk-shells inhabited by _Eupagurus bernhardus_ (see Plate VII.) often contain one of the bristle-footed worms (_Nereilepas fucata_), which may sometimes be observed to protrude its head from the shell when the Crab is feeding, and to snatch away fragments of the prey from the very jaws of its host. It is thus, in the strict sense of the word, a commensal. Species of Copepods, Amphipods, Porcelain Crabs, and even a Mysid, have been found sharing the lodging of Hermit Crabs in a similar way, and in addition there are various parasites, presently to be mentioned, found on the Crabs themselves, so that each Crab forms the centre of a whole community of widely diverse organisms all more or less directly dependent on it. A habit similar to those of some Hermit Crabs is that of the Crab _Dromia_ (see Plate IX.), mentioned in a previous chapter, which carries, as a cloak, a mass of living sponge, holding it in position by means of the last two pairs of legs. Even the "masking" habit of the Spider Crabs, already described (p. 96), may be regarded as a kind of symbiosis, since the sponges, zoophytes, etc., which grow on the Crabs no doubt benefit by being carried about in return for the protection they give. [Illustration: FIG. 68--A, THE CRAB _Melia tessellata_ CLINGING TO A BRANCH OF CORAL, AND CARRYING IN EACH CLAW A LIVING SEA-ANEMONE; B, ONE OF THE CLAWS FURTHER ENLARGED TO SHOW THE WAY IN WHICH THE ANEMONE IS HELD. (After Borradaile.)] One of the strangest habits is that of certain little tropical Crabs, of which _Melia tessellata_ (Fig. 68) is the best known, which carry in each claw a living Sea-anemone and use it as a weapon. The claws or chelipeds are in this case of small size, so that they would be of little use by themselves for attack or defence; but the fingers are provided with recurved teeth, enabling them to take a firm hold of the slippery body of the Anemone. Particles of food caught by the tentacles of the Anemone are removed and eaten by the Crab, which uses for the purpose the long walking legs of the first pair. The same limbs are also used in the process of detaching the Anemones from the stone on which they may be growing. The Anemones do not appear to suffer from the rough treatment to which they are subjected, but whether they can reap any benefit from the partnership is very doubtful. [Illustration: FIG. 69--THE COMMON PEA CRAB (_Pinnotheres pisum_), FEMALE. NATURAL SIZE.]