Page:Encyclopædia Britannica, Ninth Edition, v. 6.djvu/570

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538
CRAB

Neptune and Amphitrite, in the gardens at Marly ; Justice and Force, at Versailles ; and statues, in which the likenesses are .said to have been remarkably successful, of most of the celebrated men of his age, including Louis XIV., Louis XV., Colbert (at Saint-Eustache), Mazarin (in the church des Quatre- Nations), Conde" the Great, Maria Theresa of Austria,, Luvois, Turenne, Vauban, Cardinals de Bouillon and de Polignac, Fenelon, Racine, Bossuet, Comte

d Harcourt, Prince de Fiirstenberg, and Charles Lebrun.

CRAB, a name common to all the species of short-tailed Decapod Crustaceans (Brachyura), as well as to the forms intermediate between the short-tailed and long-tailed groups (Aiiomoura), and derived from the Latin Carabus, the name by which the common edible species was known to the Romans. The abdomen in the true crabs is short, and is completely folded beneath the breast. In the female this part is broad and rounded, and bears certain leafy appendages to which the ova are attached before spawning ; in the male the abdomen is much narrower and is somewhat triangular in shape. Like all other Decapod Crustaceans crabs are furnished with ten legs, of which the anterior pair are modified so as to form nippers powerful prehensile organs and principal weapons of offence. These are largest in the male, and the right claw is generally larger than the left. The other limbs usually end in a single claw, which in the posterior pair in swimming-crabs is more or less flattened and paddle-like ( Plate X. fig. 2). Their eyes, which are compound, are placed upon stalks, measuring in some instances an inch in length (Plate X. fig. 3), and these when not in use fit into cavities in the carapace or shell which covers the entire upper surface. Crabs, like insects, undergo metamorphosis. On emerging from the egg they are provided with long tails, swimming appendages, and sessile eyes, and bear so little resemblance to the parent form that until half a century ago their con nection with the crab was altogether unsuspected. They were then known as zoeas. After moulting, the eyes appear on stalks and nippers on the anterior pair of legs, but this form is still sufficiently uncrablike to have deceived early zoologists, who described it as forming a distinct genus (Meyalops), and it is not till a further casting of the skin that the creature assumes the perfect form. As its internal parts continue to grow its external shell soon becomes too small, and is cast off, the crab generally con cealing itself until its new and greatly enlarged covering gets sufficiently hardened. This process of moulting takes place very frequently in the young crab, and gradually becomes rarer as the creature approaches its full growth, crabs being often found with oysters attached to the cara pace which from their size must have grown there for three or four years. A still more remarkable power is that possessed by crabs of reproducing limbs which have been voluntarily thrown off, or have been lost by accident. This renewal only takes place when the limb has been severed at the second articulation ; but when broken at any point nearer the extremity the creature generally succeeds in throwing off the part between.

Among tha numerous species of crabs which abound everywhere on or near the sea-coast tho following may be noticed.

(1) The Great or Edible Crab (Cancer par/urus), the Carabus of the Romans and the Partan of Scotland. This is one of tho largest, and as an article of food is certainly the mo;i valuable, of the short-tailed Decapods, being everywhere esteemed for the delicacy of its flavour. It abounds chiefly on the rocky parts of the coasts of Europe, and often measures 12 inches across the carapace, weighing in the larger specimens fully 12 B>. The prin cipal British crab-fisheries are off the north-east coast of Scotland, in the Firth of Forth, and off the coast of Corn wall; and the home produce is largely supplemented by imports from Norway. In the capture of this crustacean " crab-pots," made of wicker-work, with the entrance at the top, and baited with dead fish, are employed. These are sunk in the proper localities, and their position indicated by a piece of cork attached to a line connected with the wicker trap. In the sheltered bays of the west of Scotland this crab is also caught in calm weather by poking it from behind with a long pole, which the crustacean immediately seizes, and which is then gently shaken, making the crab adhere all the more tenaciously, and giving the fisherman the opportunity he seeks of hoisting it into his boat. When caught, crabs are kept alive till wanted by being placed in perforated boxes which are then sunk at some convenient spot in the sea. Those caught off Lizard Point are con veyed to Falmouth Harbour, where they are individually branded, and put in boxes which are then placed under water. Recently it was stated on good authority, that one of those cases having gone to pieces, thus liberating the im prisoned crabs, many of them were shortly after caught again on their old feeding-ground a distance of eleven miles from the place where they had been confined. As they had been conveyed to Falmouth by boat, it is impos sible with our present knowledge to say by what sense they were thus unerringly guided on their return journey.[1]

(2) The Shore Crab (Carcinus mcenas] is the species most commonly met with on all parts of the British coast. Although found in deep water, its favourite haunts are beneath the stones that lie between low and high water mark, and its awkward sidelong gait as it sidles off to its place of concealment must be familiar to the most casual observer of shore life. It is a shy creature, eluding obser vation beneath stones or buried in the sand, its telescopic eyes alone visible, and feigning death when unable otherwise to cope with danger. Unlike the former species, its legs, especially the posterior pair, are flattened and ciliated so as to form swimming organs. Owing probably to the small size of this species, it has obtained little prominence as an article of food, although in flavour it is said to rival the Great Crab. Large numbers, however, are eaten by the poorer classes in seaport towns, and they are also to be had in the London fish markets. They feed chiefly on the spawn of fish and the smaller crustaceans.

(3) Pea Crabs (Pinnotheres, Plate X. fig. 5) are small

crustaceans ii which the sexes so differ that the males and females were at one time described as separate species. The female is larger than the male, and its external covering is softer ; arid they are further remarkable in taking up their residence in the shells of living bivalve mollusks, especially in the pinna, the cockle, and the mussel. The soft-bodied female is never found outside of its adopted shell, although the harder cased male is thus occasionally met with. The Pinna Pea Crab (Pinnotheres veterum), which abounds in the Mediterranean, makes its home in the pinna shell, and ancient writers have given highly imaginative descriptions of the object of this alliance between crustacean and

mollusk. It was believed that on the entrance of food




  1. The male crab is generally larger than the female, especially in its claws, and is more sought after as a table delicacy ; the flesh of both sexes immedi ately after the casting of the shell is watery and unwholesome. During moult ing the female is generally guarded by a male, which if removed is shortly re placed by another, and it is after the completion of the moulting process in tho female that the union of the sexes takes place. The spawn is carried for a con siderable time on the abdominal appendages before being deposited, an operation whicl takes place in spring and summer. Recently fears weic entertained that through over-fishing the stock of crabs in British waters was being seriously diminished, and a commission at present (1877) sitting was appointed to take evidence on this matter at the principal seats of the crab fishery. From the evi dence already collected it appears that these fisheries are now much less produc tive than formerly, and that the size of the crabs has greatly diminished, while their cost has enormously increased; for while forty years ago a dozen of the largest crabs could be had for 10d., the same number of medium sized specimens now costs 3s. Those who have given evidence are generally in favour of a 8-inch gauge in order to prevent the wanton destruction of youug crabs, and also of a close time ; but great diversity of opinion exists as to the best season for this, although the period from the beginning of June to the end of August is that most generally recommended.