CHAPTER XI 



THE FOOD OF ANIMALS— CARNIVOROUS CRUSTACEA 



AND KING-CRABS 



Air-breathing Arthropods having been now briefly reviewed, 

 so far as carnivorous species are concerned, we now turn to 

 aquatic Arthropods, breathing the air dissolved in water by- 

 means of more or less complicated gills, except in the case of 

 some very small creatures which are able to perform this function 

 by the general surface of the body. Amongst such forms by far 

 the largest and most important class is that of the Crustacea, 

 including lobsters, crayfish, shrimps, prawns, crabs, and a host 

 of other forms. A very large number of these are carnivorous, 

 some being adapted for the capture of living prey, while others 

 feed on carrion. Indeed it may be said of the group that to a 

 large extent they act as scavengers. The members of the King- 

 Crab class {Xiphosura) are also carnivorous. 



CRUSTACEANS (Crustacea) 



It will be convenient first of all to consider the Higher 

 Crustacea (Malacostraca), and afterwards to turn our attention to 

 Lower Crustacea (Entomostraca). 



HIGHER CRUSTACEA (Malacostraca)— STALK-EYED 

 FORMS (Thoracostraca) 



The most familiar members of this subdivision belong to the 

 Decapoda, or Ten -legged Crustacea, of which the Lobster 

 {Homarus vulgaris) has already been described as a type (vol. i, 

 pp. 402-409). In such a form we can at once detect characters 

 having relation to a predaceous habit, among which may be 

 more particularly mentioned the huge pincers and the well- 

 developed sense-organs, including more especially stalked com- 



