90 ANIMALS OF THE SEASHORE 



detritus on the sea bottom. Some, like most of the 

 starfish and holothurians, swallow mud and digest 

 the organic matter out of it 



Arbacia punctulata Lamarck 



(Purple Sea Urchin ; Sea Porcupine) 



PLATE VI. Fig 9 



This sea urchin ranges from Cape Cod to the 

 West Indies and Gulf of Mexico and is the only 

 urchin ever found in considerable numbers along 

 the New Jersey coast. The test or shell is from 1 to 

 2 inches in diameter and is usually deep purple in 

 color. It is thickly covered with spines from % to 

 to 1 inch in length. 



It lives in shallow water down to 25 fathoms or 

 more all along the New Jersey coast and occasionally 

 in the inlets and thorofares. After storms the beach 

 is often strewn with tests of this species. 



This sea urchin may walk fairly rapidly by 

 means of its spines. 



Strongylocentrotus drobachiensis Miiller 



(Green Sea Urchin) 



PLATE VI. Fig. 10 



This is the common sea urchin of the Maine 

 coast. The test is usually greenish and the spines 

 are shorter than in the above species. New Jersey 

 specimens are very small and restricted to deep 

 water (32 fathoms). It is an arctic and subarctic 

 species, ranging south, in deep water, to Chesapeake 

 Bay. 



