The Spinous Squat-lobster (Galathea strigosa) has spines on his hands along both the inner and the outer margins; and the antennæ are so long that if extended over the back they will reach for some distance beyond the tail. Its colour is inclined to red, with spots and lines of blue. These are the only two we are likely to find in our stone-turning, and even strigosa appears to be more at home in deeper water. According to Couch and Spence-Bate, dispersa is the commonest form in Cornwall below the low-water mark. Nexa is also a deep-water species.
At extreme low water (spring-tides) one may be so fortunate among these rocks to come across a stray lobster or two. Just outside you can see the corks which mark the ends of the long series of lobster pots that are put down to catch them, so that it is not very far for them to stray up to this level. I think my readers could be trusted to know the Lobster (Astacus gammarus) if they saw it, without bothering them with a description? Probably they would not be expecting to see a creature with a coat of the same colour as the uniform of a grenadier guard, instead of blue-black relieved on the underside by dull orange. They may also be trusted to know the Spiny Lobster, Crawfish or Greek (Palinurus vulgaris), with its very horrid carapace of purplish brown, its lack of heavy pincer-legs, its red-tinted white legs, and its long, thick and strong antennæ. If you do not come across either of these at low-water, you may see them when the crabbers bring in their catches. Their boats should be watched as they come in each morning, for you can frequently pick up deep-water specimens of Echini, spider-crabs, and so forth, that have dropped out of the crab-pots into the boat.
PRICKLY SPIDER-CRAB.
On our south-western shores you will see, brought in by the crabbers, or occasionally at liberty among the rocks, a rough, long-legged fellow called the Prickly Spider-crab, Corwich, or Gabrick (Maia squinado), with a convex carapace of oval form, the broadest part behind. His pincer-legs are but little thicker, though much longer, than the others. On that account he is not greatly esteemed as merchandise, but his flesh is far sweeter than that of the Great Crab. He is a creature of slow and languid habit, who takes as much pains with the “get-up” of his carapace as a lady does with her hair or her bonnet. His notion is to make it look like a rough piece of rock, with its characteristic flora and fauna, and to this end he takes cuttings of plants, sponges, ascidians, and anemones, and giving them a lick with his lips, as though they were postage stamps, he carefully sticks them in the valleys between the spines and tubercles on his back, adjusting them by means of his conveniently long arms. The seeker after zoophytic treasures might look in many a worse place for them than on the Gabrick’s back.
We have now done as much as possible with the crabs of the rocky shore, and must shift our ground for a while to the flat sands that run out from the upper part of the bay, and taking advantage of the very lowest tides, must go, armed with trowel or spade, to dig in the treacherous sands. Many things we may find other than those we came specially to seek, and those we specially want just now may not come to light; still it is in the sand we shall find the Masked-Crab and the Angular-Crab, if they occur in the district.
THE MASKED-CRAB (MALE).
The Masked-crab (Corystes cassivelaunus) has a carapace that is much longer than it is broad, almost elliptical in outline, and so marked with depressions that some specimens present a remarkable likeness to a human face, more especially so if the crab is held in a way that will accentuate the prominences by casting small shadows. It is prettily coloured with yellow and red. The male has deeper tints than the female, and his pincer-legs are much longer than hers. Their habit is to burrow into the sand in rather deep water, and lie buried, with only the tips of their long antennæ at the surface. These antennæ are furnished with a double row of hairs throughout their length, and by placing the antennæ so close together that these hairs interlock, a tube is formed through which the crab can draw in the current of water necessary for respiration. After storms, great numbers of this crab are sometimes cast up on the shore, dead.
Another crab of singular aspect is the Angular-crab (Gonoplax rhomboides), so-called on account of the many sharp angles of the flesh-tinted carapace. Its pincer-legs look as though they had been drawn out when the animal was soft, for in the adult male they are quite four times the length of the carapace—in the female and young male they are much less. Another distinction of the sexes will be found in the colour of the moveable finger of the pincers, which is black in the male only. The eyes are mounted on such long stalks that they reach nearly to the sides of the carapace, which run out into a long sharp spine at each front corner for the protection of the eyes. These are mounted very much like the eyes of the Racer-crab (Ocypoda) of other lands, and they are used for a similar purpose. The footstalks are erected so that the crab can see over a wider extent of territory, and behind as well as before. They appear to live in excavations in the mud on our southern and western coasts. They are much esteemed as food by various kinds of fish, and many specimens have been taken from the stomach of the cod particularly.
If it be desired to keep living crabs for the purpose of observing them, a shallow vessel will be found the best; or at least, a vessel in which they can easily get into shallow water. Provision should always be made whereby a crab can climb right out of the water, yet so that he cannot get out of the vessel; otherwise he will wander all over the house, and either get stepped upon, or get dried up in some obscure corner. It must be remembered that the crab consumes much oxygen, and if specimens of any size are put into tanks containing more delicate creatures, much harm may result. It should also be borne in mind that they are of ravenous and omnivorous appetite, and your choice specimens of soft-bodied creatures will not be held sacred by the crabs. We should therefore advise a separate receptacle for crustaceans; and some of the smaller, more delicate kinds, must be kept each in their own vessels. The smaller species will probably be able to pick up sufficient food from the minute animal and vegetable life of your tanks, but the large ones will require to have food specially provided for them. Small pieces of fish will be found the most convenient for this purpose, and it will be more highly appreciated if it be not too fresh. Like the slum-boy who could not relish farmhouse eggs because they were deficient in flavour, the crab prefers his food to be kept for a time.