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THE HERMIT CRAB.
You doubtless know the Hermit Crab, by naturalists named Pagurus ? Unlike other crabs, who are content to live in their own solid shells, Pagurus lives in the empty shell of some mollusc. He looks fiercely upon the world from out of this apparently inconvenient tub, the Diogenes of Crustacea, and wears an expression of conscious yet defiant thest, as if he knew the rightful owner of the shell, or his relatives, were coming every moment to recover it, and he, for his part, very much wished they might get it. All the fore part of Pagurus, including his claws, is defended by the solid armour of crabs. But his hind parts are soft, covered only by a delicate membrane, in which the anatomist, however, detects shell-plates in a rudimentary condition. Now a gentleman so extremely pugnacious, troubled with so tender a back and continuation, would fare ill in this combative world, had he not some means of redressing the wrong done him at birth; accordingly he selects an empty shell of convenient size, into which he pops his tender tail, fastening on by the hooks on each side of his tail; and having thus secured his rear, he scuttles over the sea-bed, a grotesque but philosophic marauder. You ask how it is that this tendency to inhabit the shells of molluscs became organised in the hermit
crab? Either we must suppose that the crab was originally so created,-designed with the express view of inhabiting shells, to which end his structure was arranged; or-and this I think the more reasonable supposition that the hermit - crab originally was furnished with shell-plates for the hinder part of his body, but that these have now become rudimentary, in consequence of the animal's practice of inhabiting other shells, -a practice originally resorted to, perhaps, as a refuge from more powerful enemies, and now become organized tendency in the species.
Be this as it may, the hermit-crab will not live long out of an appropriated shell; and very ludicrous was the scene I witnessed between two taken from their shells. Selecting them nearly equal in size, I dropped them, “naked as their mother bore them,” into a glass vase of sea water. They did not seem comfortable, and carefully avoided each other. I then placed one of the empty shells (first breaking off its spiral point) between them, and at once the contest commenced. One made direct for the shell, poked into it an inquiring claw, and having satisfied his cautious mind that all was safe, slipped in his tail with ludicrous agility, and, fastening on by his hooks, scuttled away, rejoicing. He was not left long in undisturbed possession. His rival approached with strictly dishonourable intentions; and they both walked round and round the vase, eyeing each other with settled malignity,—like Charles Kean and Wigan in the famous duel of the Corsican Brothers.2 No words of mine can describe our shouts of laughter at this ludicrous combat,one combatant uneasy about his unprotected rear, the other sublimely awkward in his borrowed armour. For the sake of distinctness, I will take a liberty with two actors' names, and continue to designate our two crabs as Charles Kean and Alfred Wigan. C. K., although the blacker, larger and stronger of the two, was at the disadvantage of being out of his shell, and was slow in coming to close quarters; at last, after many hesitations, approaches and retreats, he made a rush behind, seized the shell in his powerful grasp, while with his huge claw he haled Wigan out, flung him discomfited aside, and popped his tail into the shell. Wigan looked piteous for a few moments, but soon, his “soul in arms and eager for the shell,” he rushed upon his foe; and then came the tug of crabs! C. K, had too firm a hold; he could not be dislodged. I poked his tender tail, which was exposed through the broken shell, and he vacated, leaving Wigan once more in possession. But not for long. Once more Wigan was clutched, haled out, and flung away. I then placed a smaller shell, but perfect, in the vase. Kean at once quitted his dilapidated roof, and ensconced himself in this more modest cottage, leaving Wigan to make himself comfortable in the ruin ; which he did.
The fun was not over yet. A third hermit-crab was placed in the vase. He was much smaller than the other two, but his shell was larger than the one in which Kean liad settled, as that unscrupulous crab quickly perceived, for he set about bullying the stranger, who, however, had a shell large enough to admit his whole body, and into it he withdrew. It was droll to see Kean clutching the shell, vainly waiting for the stranger to protrude enough of his body to permit of a good grasp and a tug; but the stranger knew better. He must have been worn out at last, however, for although I did not witness the feat, an hour afterwards I saw Kean comfortable in the stranger's house. They were changed again; but again the usurpation was successful. On the third day I find recorded in my journal: “The crabs have been fighting, and changing their abodes continually. C. K. is the terror of the other two, and Wigan is so subdued by constant defeats that he is thrown into a fluster if even an empty shell is placed near him; and although without a shell himself, which must make him very cold and comfortless in the terminal regions, he is afraid to enter an empty one. The terrors of the last two days have been too much for his nerves : one must almost question his perfect sanity; he is not only beside his shell, but beside himself. The approach of C. K. throws him into a trepidation, which expresses itself in the most grotesque efforts at escape."
A new experiment was tried. Throwing a goodsized whelk into the vase, I waited to see Kean devour the whelk in order to appropriate his shell; for the house he last stole, though better than the previous houses, by no means suited him, Mr. Bell, in his History of British Crustacea, conjectures that the hermit-crab often eats the mollusc in whose shell he is found—a conjecture adopted by subsequent writers, although Mr. Bell owns that he never witnessed the fact. My observation flatly contradicted the conjecture. Kean clutched the shell at once, and poked in his interrogatory claw, which, touching the operculum of the whelk, made that animal withdraw and leave an empty space, into which Kean popped his tail. In a few minutes the whelk, tired of this confinement in his own house, and all alarm being over, began to protrude himself, and in doing so gently pushed C. K. before him. In vain did the intruder, feeling himself slipping, cling fiercely to the shell; with slow but irresistible pressure the mollusc ejected him. This was repeated several times, till at length C. K. gave up in despair, and contented himself with his former shell. Thus, instead of eating the whelk (which, I may remark in passing, the crab never does, even in captivity, where food is scanty), he had not even the means of getting him out of his shell, and the conjecture of our admirable naturalist must be erased from all Hand-books.