THE ECHINODERMS 195 



Brittle stars. The arms of the brittle stars and basket 

 fish (Fig. 115) are noticeably different from those of the starfish. 

 They are slender, and exceedingly flexible, but easily broken off ; 

 hence the name brittle star. 



The food of the brittle stars consists of minute organisms 



FIG. 115. A basket star. (From Clark.) 



and decaying organic matter lying on the mud of the sea bot- 

 tom. It is scooped into the mouth by special tube feet. Loco- 

 motion is comparatively rapid. The arms are bent laterally, 

 and enable animals belonging to certain species to " run," or 

 climb, and probably to swim. 



