290 THE OCEAN WORLD. 



spines are brought into action, throwing up the sand with increased 

 activity, while the sand thrown up, returning again, soon covers the 

 body of the worker, and he has soon buried himself beneath the 

 surface. In this situation the long hair-like spines situated upon the 

 back begin to play their part ; they prevent the sand from entirely 

 covering the . animal by forming a little round hole, through which 

 water is introduced to the mouth and respiratory organs." The hiding- 

 place of the sea-urchin is, however, easily detected in the sand by the 

 hole thus arranged for the respiration of the animal, and the fishermen 

 think they can predict storms according to the depth of the hole. 



The Echinidae are reproduced by eggs, which are red and nearly 

 microscopic. As it issues from the egg the larva has the appearance 

 of a very minute fish. It is not at once converted into the perfect 

 animal, but undergoes a certain metamorphosis analogous to that of 

 the caterpillar into the butterfly. But, as we have already stated in 

 treating of the Asterise, it produces, at a certain stage, by some sort 

 of internal process of generation, a sea-urchin, which, being at first 

 only an organ of the larva, begins to live an independent life when 

 the nursing larva has destroyed itself. The manner in which the 

 urchin unfolds itself at the expense of the larva is quite analogous to 

 that which the asterias present : it is another case of alternate gene- 

 ration, of which our space does not permit us to give even a general 

 outline. 



Sea-urchins are found in every sea ; they dwell in sandy bottoms, 

 and sometimes upon rocky ground. They are caught with wooden 

 pincers when in shallow water ; when found at the water's edge, they 

 may be taken by a gloved hand. 



The urchin, like the crab, which it also resembles in taste, becomes 

 red when boiled ; only certain species are comestible, however. In 

 Corsica and Algeria the Melon-shaped Urchin (Echinus melo) is much 

 esteemed. In Naples and in the French ports of the Channel the 

 Echinus lividus is eaten. In Provence the Common Sea-urchin 

 (Echinus esculentus and Echinus granulosus) are the favourites. 



Sea-urchins are eaten raw like oysters. They are cut in four 

 parts, and the flesh taken out with a spoon; they are sometimes, but 

 more rarely, dressed by. boiling, and eaten from the shell like an egg, 

 using long sippets of bread : hence the name of sea-eggs, which they 

 bear in many countries. 



