CRAB 



539 



the ri^ht great daw against a sharp edge of 

 tin- -.ivniul j.iint. The Calling Cnih (Gelaimus) 

 makes Inrx" 1 burrows, ami tin- male clone* the 

 mouth of til*- hole with itH exaggerated great claw. 

 The Pea-crabs (Pinnotheres) li\.' in-i'lr bivalves 

 ( Pinna, MytiliiH, Mactra, &c. ). One species 

 (P. veternin ) was said by the ancients to nip the 

 mollusc when danger threatened, and to receive its 

 share of food in return. There is no doubt on to 

 the share of food, but no evidence that the crab 

 rewards its host. In the genus Telphusa all the 

 species live in fresh water in the warm parts of the 

 globe. The European species (T. fluviatilis) is 

 tolerably common in southern Europe, was known 

 to the ancients both in its habit and edibility, and 

 is often figured on Sicilian coins. As regards 

 geological distribution, the Brachyura do not 

 certainly appear before the upper Jurassic, and 

 become gradually more numerous in Cretaceous 

 and Tertiary strata. 



Moulting and Amputation. Like other crusta- 

 ceans, crabs periodically cast their chitinous and 

 limy shells. The moults are most frequent in 

 youth, when the rapid growth of the body conflicts 

 with the rigidity or the armature. Extra feeding 

 may accelerate 'the process. Before moulting the 

 old shell becomes virtually dead, reserve stores are 

 used in fresh growth, a new shell begins to form 

 within the old, and finally with considerable, and 

 sometimes fatal effort, the shell is cast. It is left 

 in apparent intactness, a very image of its 

 lost tenant. The new suit, which is at first 

 soft, requires several hours or days to acquire 

 firmness. The loss of internal linings, of stomach 

 mill, of the outer covering of the eyes, &c., as 

 well as of the entire outer armature, leaves the 

 crab very much hors tie combat. The period is 

 one of great disadvantage to the crabs, not 

 only from the fatigue and often fatality of 

 the process, but from the state of defenceless 

 helplessness in which they are temporarily left. 

 In many cases crabs lose their limbs in fighting, 

 and they may voluntarily resign them (as in 

 Porcellana platychelys ) to save their bodies. Sudden 

 panic or injury is said to lead to similar self- 

 inflicted amputation or 'autotomy.' Like many 

 animals lower in the scale, crabs are able to make 

 good their injuries, though several moults are 

 required to regenerate a limb. 



Masking. A common habit among crabs is that 

 of masking themselves with foreign objects. Thus 

 both the European species of Maia ( M. squinado 

 and M. verrurosa ) are usually overgrown by Algie, 

 Hydroids, and Polyzoa ; the same is true of Pisa ; 

 in Inachus the long feet are especially well con- 

 cealed by seaweeds ; our common Stenorhynchus is 

 often covered by a sponge growth ; the "Mediter- 

 ranean Dorippe lanata uses its hind -legs to carry 

 some living or dead object upon its back, and thus 

 very emphatically asserts its innocence ; the common 

 Drotnia (D. vulgaris) holds sponges on its back in 

 similar fashion. See Co.MMENSALlSM. 



Intelligence. As in several features of their 

 structure, so in their intelligence, crabs appear to 

 hold the highest place among crustaceans. Mose- 

 lev observed how a sand -crab (Uct/poda ippeus), 

 which dreads the sea, dug itself into the sand and 

 held on against the undcrtide of each great wave. 

 Romanes refers to the alleged habit of the common 

 crab in stationing a hara-shelled individual as 

 sentinel during the moulting season. There seems 

 to be not a little of the intelligent in some cases 

 of crab-commensalism. Darwin nas, however, given 

 a crowning instance of intelligence which is worth 

 many less emphatic. Some shells were thrown 

 towards the hole of a burrowing shore-crab (Gela- 

 simus). One rolled in, three remained a few inches 

 from the mouth. In a few minutes the crab came 



out, Ix-aring the shell which had fallen in, and re- 

 moved it to the distance of a foot. ' It then saw 

 the three other shellh lying near, and evidently 

 thinking that they might likewine roll in, carried 

 them to the spot where it had laid the Brut." 



Common British Forms. The Common Shore- 

 crab ( Carcinus mtenas); the Great Crab (Cancer 

 pagurus), so much eaten; the Slender Spider-crab 

 or Slender-beaked Crab (Stenorhynchus tenuiros- 

 tris), with very long spider-like legs and bright 



Slender Spider-crab (Stenorhynchus tenuirottrty. 



pink triangular body ; the large Thorny Spider- 

 crab ( Maia squinado ) ; the Common Swimming 

 Crab (Portunus variegatus), common on Scotch 

 coasts, with the last pair of legs flattened like oar- 

 blades; the Velvet Fiddler-crab or Devil-crab (For- 

 titmis puber), with a brown hairy shell; the 

 Maskea Crab (Corystes cas&ivelannus), with a cara- 

 pace marked so as to suggest a mask, often found 

 buried in the sand of English and Welsh coasts ; 

 the small Four-horned Spider-crab ( Pisa tetraodoii ) ; 

 the little Pea-crab (Pinnotheres pisum, &c.), inside 

 bivalves, are familiar British species. 



Classification. Crabs are generally classified ac- 

 cording to the shape of their cephalothorax into five 

 families : ( 1 ) Catometopa, usually quadrangular 

 e.g. Ocypoda, Grapsus, Pinnotheres, Gecarcinus; 

 (2) Cyclometopa, usually broad, narrowed behind, 

 bow-shaped in front e.g. Telphusa, Cancer, 

 Portunus, Carcinus ; ( 3 ) Oxyrhyncha, triangular, 

 pointed in front e.g. Maia, Pisa, Hyas, Steno- 

 rhynchus, Inachus ; (4) Oxvstomata, usually round 

 e.g. Calappa, Ilia; (5) l^otopoda, with the last 

 or last two pairs of limbs more or less turned back 

 e.g. Dorippe, Porcellana, Lithodes, Dromia. 



See CRUSTACEA, CRAYFISH, HEKMIT-CRAB, LOBSTER. 

 Besides general works mentioned under Crustacea, see 

 Balfour's Embryology ; W. K. Brooks, Handbook of In- 

 vertebrate Zoology (Boston, 1882); Fr&lencq, Archiv. 

 Zooloyie Expfr, (1883); Huxley's Invertebrates; Romanes, 

 Animal Intelligence (Inter. So. Series, 1886); Carus 

 Sterne, Wei-den vnd Vergehen (1886); Woodward, in 

 Cassell's Natural History. 



Crab. ROGER, hermit, was born about 1621 in 

 Buckinghamshire, and served for seven years 

 (1642-49) in the Parliamentary army. He then 

 set up in business as 'a haberdasher of hats' at 

 < 'In-sham, in his native county. He had imbibed 

 the idea that it was sinful to eat any kind of 

 animal food, or to drink anything stronger than 

 water; and in 1651, determined to follow literally 

 the injunction given to the young man in the 

 gospel, he sold off his stock-in-trade, distributing 

 the proceeds among the poor, and took up his 

 residence in a hut. His food consisted of oran, 

 turnip-tops, dock-leaves, and grass. The persecu- 

 tions the poor man inflicted on himself caused him 

 to be persecuted by others, cudgelled, and put in 

 the stocks. He was four times imprisoned for 

 sabbath-breaking and other offences, vet still he 

 persisted in his course of life. He puolished The 

 English Hennite, Dagon's Downfall, and a tract 



