50 



SEA-SHORE LIFE 



They have no spines and their skeleton is often reduced to minute 

 anchor-shaped spicules within the skin. The mouth is at one end 

 of the worm-shaped body, and is surrounded by feathered or 

 branching tentacles. In some species there are five double rows 



Fig. 24; Variations of tlie COMMON STARFISH. 

 From Long Island Sound. 



of tube-feet down the sides of the body, but in others these are 

 absent. When disturbed sea cucumbers have the curious habit of 

 casting out their viscera, and afterwards regenerating them. They 

 are sluggish creatures, and either live within the sand or under 

 rocks or crawl slowly over the bottom, feeding upon minute organ- 

 isms that are contained in the sand or mud which they swallow. 



Sea urchins or Echini may be compared to starfishes Avithout 

 arms. They are usually provided with a skeleton made for the 

 most part of six-sided plates fused or rigidly joined together. 

 They have five sharp-edged teeth with which they gnaw off minute 



