58 



SEA-SHORE LIFE 



. ..iHs*ai«e«**«»-»- - 



Fig. 30; BASKET STARFISH. Tortugas, Florida. 



with a tough skin. The basket star feeds upon unlucky fishes 

 which may seek a retreat within the branches of the trellis, only to 



be seized and devoured. 

 It is found along our 

 North Atlantic coast 

 from the eastern end of 

 Long Island north- 

 ward, and although 

 rare in shallow water, 

 it is abundant at depths 

 of twenty feet or more, 

 being especially com- 

 mon off Provincetown 

 or in Eastport Harbor. 

 The Purple Sea Ur- 

 chin, (Arhaeia pune- 

 tidata, Fig. ^iy), a dark 

 brown or brownish-purple sea urchin, is quite common on broken 

 rocky bottoms along our coast from Mexico to Cape Cod. The body 

 is globular and hejnispherical, 

 and about one and three-quar- 

 ters inches in diameter. It is 

 protected by a skeleton formed 

 Avithin the skin, and composed 

 for the most part of six-sided 

 calcareous plates arranged in 

 an orderly manner. The body 

 is covered with conical spines 

 of various lengths up to about 

 three-quarters of an inch. These 

 are found chiefly in five broad 

 radii regularly spaced around 

 the body, while between these 

 spiny areas one sees five nar- 

 row spaces almost devoid of 



spines. There are five double rows of tube feet provided with ter- 

 minal suckers. These arise in the spiny areas and may stretch 

 out so as to become longer than the spines themselves. At the 



Fig. ,,v/ PURPLE SEA URCHIN. 

 Cold Spring Harbor, Long Island Sound. 



