84 The Under-Water World 



or more feet from the ground. Early 

 explorers were puzzled by the presence 

 of large marine shells high up on the 

 mountain sides, until it was discovered 

 that they had been carried there on the 

 backs of the crabs that had died 

 possibly from a too long absence from 

 the sea. In many hermits the gill- 

 chambers are so constructed that the 

 animal can spend considerable periods 

 out of water. This is very marked in 

 the robber crab of Christmas Island 

 which lives in burrows lined with the 

 fibre torn from the coconuts. It lives 

 largely upon fallen nuts, but will on 

 occasions climb up a forty-foot palm 

 tree to obtain fresh fruit. Having 

 gathered the nuts it breaks in the eyelet 

 holes with its immense pincers and feasts 

 on the kernel. But the robber crab is 

 not confined to a fruit diet, for like most 

 crabs he is a scavenger. He closes the 

 door of the burrow with one big claw 



