82 



Part second. 



it to pieces. Tlie shell thus serves as a protection and is usually 

 so large, that the Hermit-crab can withdraw itself entirely from 

 view in case of danger. Growth brings great difficulties for the 

 Hermit-crab: firstly, that common to all crustaceans, of moulting, 

 and secondly the special change of home. For when he has in- 

 creased in size he must naturally exchange his old house for a 

 more roomy one and this he does with great circumspection. 

 When he has found a shell suitable for his purpose he first ex- 

 amines it carefully all over, poking his claw far into the cavity to 



Fig. 162. Paguriis stTtatus, taken ont of its snail-shell, to show the soft, 

 worm-like abdomen. 



assure himself that there is nothing suspicious lurking within it; 

 then if all is right he cautiously prepares to effect the removal. 

 He gets hold of the shell with his claws, places it in an upright 

 position with the opening towards himself and, with one quick 

 dart, forsakes his old home and slips into the new one, as if he 

 knew what a tit-bit his soft juicy body would be for some hungry 

 fish. 



But why should often three or even six Sea-anemones be 

 attached to the shell occupied by the Hermit-crab, and yet 

 be in no way organically connected with the crab? It is ev- 

 idently a mutual benefit association formed by the crab and the 



