178 



SCIENCE-GOSSIP. 



[August 1, 1866. 



Fig. 164. Spiny Spider Crab — (Maia Squmado). 



SPIDER-CRABS AND THEIR PARASITES. 



rpHAT excellent naturalist Mr.' Edward Jesse, in 

 ■*- a short article entitled " The Spider-Crab," in 

 " Once a Week " (July 9th, 1S59), says :— " There is 

 a very small species of crab at Bognor, the spider- 

 crab, which has its body and claws covered with 

 numerous minute hooks, scarcely perceptible to 

 the naked eye, but perfectly so with the aid of a 

 magnifying-glass. It may be asked 'What are 

 these hooks ? ' You shall hear. This crab is a 

 prodigious coxcomb, and very careful of its own 

 precious person. Either for the purpose of con- 

 cealing itself from its enemies, or from an innate 

 love of finery, it selects a quantity of seaweed, 

 always preferring the most gaudy colours, those 

 chiefly red. Having selected them, he cuts them 

 into fine thread-like strips, and runs them through 

 the hooks. When he has completed his toilette, 

 he appears one mass of seaweed, thus not only 

 disguising himself from those enemies which might 

 otherwise make him their prey, but perhaps feeling 

 himself the best-dressed crab in the neighbourhood. 

 It is also remarkable that this labour for making his 

 toilette is renewed every morning, so that the quan- 

 tity of seaweed consumed is very great. This may 

 be observed by any -one who has the opportunity of 

 keeping these comical little crabs in an aquarium, 

 although I regret to add that they do not live long 

 in a state of confinement." Mr. Jesse says that he 



wrote this from his own observation, though the 

 discovery of the crab's habits was made by some 

 friends of his. The paragraph I have quoted " went 

 the round of the papers " at the time, and I, who 

 then kept an aquarium shop in London, was soon 

 favoured jyith many orders for " the Vanity Crab," 

 "the Dandy Crab," "the Crab that togs himself 

 out in seaweed," and so forth. Mr. Jesse adds 

 "they are caught in considerable numbers at 

 Bognor, together with another crab, about the 

 same size as the spider-crab, but which is not 

 furnished with hooks. On speaking to the Bognor 

 fishermen respecting the latter, I found they all 

 entertained the idea that the seaweed grew on them. 

 The thread-like weeds may, however, be drawn out 

 of the hooks one by one, until the little dandy is 

 left perfectly bare." 



However, the fishermen were right, and Mr. 

 Jesse and his friends were wrong, for the seaweeds 

 do grow upon the shell of the crab, and are not 

 temporarily attached, as Mr. Jesse describes. It 

 is probable that the Crab referred to is the four- 

 horned spider-crab (Pisa tetraodon), and Professor- 

 Thomas Bell, in his " History of British Stalk-eyed 

 Crustacea " (8vo. 1S53, pp. 24 25), treating of this 

 Crab (which is eminently a Bognor species, by the 

 way), says " it is found concealed under the long 

 hanging fuci which clothe the rocks at some distance 

 from the shore. . . . Like all slow-moving 

 Crustacea, they are liable to be covered with small 



