MARINE ARTHROPODS 



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prominent and spiny, and the long abdomen is narrower in front 

 than in the middle. This creature hides in the holes that have 

 been excavated by boring molluscs, and seems also to extend the 

 cavities it inhabits by its own labours. 



The other is very similar in general form, but has no spiny 

 beak and the abdomen is much broader in the middle than at the 

 base. It is also to be distinguished by the very unequal size of its 

 front legs, one of which is much more developed than the other. 



It is known as the mud-burrower (Callianassa subterranea), 

 and is said to burrow very deeply into mud-banks, scooping out its 

 retreat principally by means of the second and third pairs of legs. 



Fio. 209. THE MUD-BORER (Gebia stellata) (1) AND THE MDD-BURROWER 

 (Callianassa subterranea) (2) 



Although found at times between the tide-marks, its principal 

 habitat is probably in the mud that is covered by deep water, for 

 it is not uncommonly to be found in the stomachs of fishes that 

 habitually feed in such localities. 



Lobsters of all kinds, and, indeed, the marine crustaceans 

 generally, are essentially the scavengers of the sea, for they are 

 carrion-feeders, greedily devouring flesh in all stages of decompo- 

 sition. Hence the value of their work on the sea shore is very 

 considerable. 



An examination of shrimps and prawns will at once show 

 their close relationship with lobsters. The general build of their 

 bodies is practically the same, and their appendages, though often 



