186 



MARINE ANIMALS 



holes into which they can withdraw by means of their contractile 

 stalks. 



A great number of crabs and small crustaceans dig burrows in the 

 sand — for example, Haploops tubicola (Fig. 25), and among decapods, 

 the thalassinids, Gebia in the North Sea, Callianassa in the Mediter- 

 ranean, and the shrimp Crangon in the Baltic; the last three are repre- 



;-'-— -_-«fc|l|jjfSg- —=■ 



Fig. 23 Fin. 24 



Fig. 23. — Razor clam, Soleti pellucidm, of European seas, in the sand. Enlarged 



one and one-half times. After Meyer and Mobius. 

 Fig. 24. — Lingula anatina in sand, seen from the edge, from the side, and with- 

 drawn into its burrow. The opening of a burrow to the rear. After Francois. 



sented along the New England coast. By excavation of a space 1 meter 

 square and 30 cm. deep at the mouth of the Elbe, between tide marks, 

 Dahl secured more than 800 individuals of an amphipod (Bathy- 

 poreia) . Where they occur, the horseshoe crabs bury themselves in the 

 sand during the day, coming out at night to feed. Amphioxus must be 

 included in this list of sand dwellers, lying in the sand with only the 

 oral opening exposed (Fig. 26). 



As everywhere, the carnivores pursue their prey in this habitat also. 

 A number of predators search actively through the sand for their prey. 



