lo Papers from the Marine Biological Laboratory at Tortugas. 



do not enter on account of the presence of the adults. If they drop in by 

 chance they are almost always killed and eaten. Among the many different 

 kinds of food that Ocypoda will eat are cocoanut, sea-weed, bread, turtle- 

 meat, fish, cofifee-grounds, potatoes, ham fat, and jelly-fish. Bebe, in his 

 article on " Birds of Cobb Island," states that the sand-crab eats bird's eggs, 

 and ^'errill (1874) has found that it feeds upon Talochestia longicornis and 

 T. incgalophthaliua. When the dead body of a fish which has been washed 

 ashore is too large to be carried away by an ocypoda, it is apt to build a 

 burrow by the side of the fish and feed on it day after day. Dr. Mayer has 

 observed that when Physalia are driven up on the beach the same thing 

 occurs, and then there is usually only one burrow to each Physalia. 



Ocypodas are great scavengers and keep the beach almost free from 

 decomposing animal and vegetable matter, but there are a few things that 

 they will not eat ; one of these is the lime. Pieces of this acid fruit thrown to 

 them are seized immediately, hut one " taste " seems to be sufficient. They 

 immediately begin to rub the lime in the sand, apparently trying to get rid of 

 a substance that irritates the sensory organs of the mouth. There is no doubt 

 that this crab reacts more strongly to certain kinds of foods than to others. 



While feeding ocypodas usually congregate along the drift-line of the 

 beach, but as far as I have observed they never enter the water for the pur- 

 pose of seizing food. 



During the summer large schools of Atherina laticeps (sardine of the 

 Gulf) are almost always found close to the shore of Loggerhead Key and 

 they are an important food for Ocypoda (plate 2, fig. b). These small fish 

 were frequently used in feeding experiments. Feeding was observed both 

 while individuals were in captivity and while they were under natural con- 

 ditions. The eyes do not seem to play an important part in the detection of 

 food, although they undoubtedly serve to lead the crabs to objects which may 

 be food. When atherinas are thrown near an ocypoda (the observer being 

 concealed), the " sand-crab " usually jumps and runs toward the former as 

 though it " knew " the fish were food, but, as we shall see from other e.x- 

 periments, this is probably not the case. As soon as the fish is reached the 

 Ocypoda touches it with the claws and then immediately grabs it. As a 

 rule the Atherina is carried at once into a burrow, but often (especially in 

 case of the first few specimens) it is pinched with the claws, which are then 

 rubbed against the first pair of maxilla situated at the mouth opening. 

 Usually this process is repeated several times, alternating one claw with the 

 other, until finally the crab has succeeded in introducing some of the juice into 

 the mouth. Then it may hold the fish in one claw, using the other to tear off 

 pieces and to transfer them to the mouth-parts, or it may grab the fish with 

 either end directed toward the mouth, gnawing on it with the mouth-parts 

 Frequently the Ocypoda begins by picking out the eyes of the Atherina and 

 eatin"' them. 



