When the dwelling of the pagurus becomes inconveniently narrow, the remedy is easy, for appropriate sea-shells abound wherever hermit crabs exist. They are found on almost every coast, and every new scientific voyage makes us acquainted with new species. According to Quoy and Gaimard, they are particularly numerous at the Ladrones, New Guinea, and Timor. The strand of the small island of Kewa, in Coupang Bay, was entirely covered with them. In the heat of the day they seek the shade of the bushes; but as soon as the cool of evening approaches, they come forth by thousands. Although they make all large snail-houses answer their purposes, they seem in this locality to prefer the large Sea Nerites.
The famous East Indian Cocoa-nut Crab (Birgus latro), a kind of intermediate link between the short and long tailed crabs, bears a great resemblance to the paguri. It is said to climb the palm-trees, for the sake of detaching the heavy nuts; but Mr. Darwin, who attentively observed the animal on the Keeling Islands, tells us that it merely lives upon those that spontaneously fall from the tree. To extract its nourishment from the hard case, it shows an ingenuity which is one of the most wonderful instances of animal instinct. It must first of all be remarked, that its front pair of legs is terminated by very strong and heavy pincers, the last pair by others, narrow and weak. After having selected a nut fit for its dinner, the crab begins its operations by tearing the husk, fibre by fibre, from that end under which the three eye-holes are situated; it then hammers upon one of them with its heavy claws, until an opening is made. Hereupon it turns round, and by the aid of its posterior pincers, extracts the white albuminous substance. It inhabits deep burrows, where it accumulates surprising quantities of picked fibres of cocoa-nut husks, on which it rests as on a bed. Its habits are diurnal; but every night it is said to pay a visit to the sea, no doubt for the purpose of moistening its branchiæ. It is very good to eat, living as it does on choice vegetable substances; and the great mass of fat, accumulated under the tail of the larger ones, sometimes yields, when melted, as much as a quart of limpid oil. Thus our taking possession of the Keeling Islands, as a coaling station for the steamers from Australia to Ceylon, bodes no good to the Birgus.
The long tail, which the paguri sedulously conceal in shells, serves the shrimps and lobsters as their chief organ of locomotion, for although these creatures have well-formed legs, they make but slow work of it when they attempt to crawl. But nothing can equal the rapidity with which they dart backwards through the water, by suddenly contracting their tail. Thus the Lobster makes leaps of twenty feet at one single bound, and the little shrimp equals it fully in velocity in proportion to its size, and belongs unquestionably to the most active of the denizens of the ocean. It swarms in incalculable numbers on the sandy shores of the North Sea, where it is caught in nets attached to a long cross pole, which the fishermen, walking knee-deep in the water, push along before them. Boiled shrimps are a well known delicacy; and the Squilla Mantis of the Mediterranean, which resembles our common shrimp in outer form, but essentially differs from it in the formation of its branchiæ, which float freely in the water, attached to the abdominal legs, holds an equal rank in the estimation of the South Europeans.
Crustaceans and Oysters.
Spotted Mantis Crab.
But of all crustaceans, none approaches the Lobster in delicacy of taste. This creature, the epicure's delight, loves to dwell in the deep clear waters along bold rocky shores, where it is taken in wicker baskets, or with small nets attached to iron hoops. About two millions of lobsters are annually imported from Norway, although they are also found in great abundance along the Scottish and Irish coasts. Thus, considering their high price, they form a considerable article of trade; and yet they are far from equalling in importance the minute Herring-crab (Cancer halecum), which, by forming the chief nourishment of that invaluable fish, renders in an indirect way incalculable services to man.
The lobster breeds in the summer months, depositing many thousands of eggs in the sand, and leaving them there to be hatched by the sun. But few, as may easily be imagined, live to attain a size befitting them to appear in red livery on our tables. Like all crustaceans, the lobster casts its shell annually, and with such perfection, that the discarded garment, with all its appendages, perfectly resembles the living animal. The process is curious enough to deserve a few lines of description.
When towards autumn, the time of casting the shell approaches, the lobster retires to a silent nook, like a pious hermit to his cell, and fasts several days. The shell thus detaches itself gradually from the emaciated body, and a new and tender cuticle forms underneath. The old dress seems now, however, to plague the lobster very much, to judge by the efforts he makes to sever all remaining connection with it. Soon the harness splits right through the back, like the cleft bark of a tree, or a ripe seed-husk, and opens a wide gate to liberty. After much tugging and wriggling, the legs, tail, and claws gradually follow the body. The claws give the lobster most trouble; but he is well aware that perseverance generally wins the day, and never ceases till the elastic mass, which can be drawn out like india-rubber, and instantly resumes its ordinary shape, has been forced through the narrow passage. It can easily be supposed that, after such a violent struggle for freedom, the lobster is not a little exhausted. Feeling his weakness, and the very insufficient protection afforded him by his soft covering, he bashfully retires from all society until his hardened case allows him to mix again with his friends on terms of equality, for he well knows how inclined they are to bite and devour a softer brother.