STARFISHES, SEA-URCHINS, ETC. 93 



large to be taken into its mouth the stomach is extended 

 through the mouth and the living prey is covered over by it. 

 As soon as the shell is opened ever so little the soft parts of 

 the victim are sucked up and digested by the starfish. Having 

 finished its meal the starfish draws its stomach in and seeks 

 another oyster or clam. 



FIG. 33. Regeneration of starfishes, Linckia sp. Upper figure shows 

 a starfish regenerating arms that have been lost; the lower figure shows a 

 portion of an arm regenerating the disk and other arms. (About natural 

 size.) 



Starfish, and in fact most of the Echinoderms, have the 

 power of regenerating lost parts. If, through accident, a 

 starfish loses one or more of its rays new ones will grow out 

 to replace the old ones, or, in some cases, the arm may prac- 



