NO. 19.] ECHINODERMS OF CONNECTICUT. IQ 



CLASS I. ASTEROIDEA 



The members of this group, popularly known as starfishes, 

 are represented in Long Island Sound by three, or perhaps four, 

 species, one of which is the commonest echinoderm found along 

 the coast. They occur at all depths below low-water mark, 

 and prefer rocky and shelly bottoms as a rule, because the 

 mollusks which constitute a large part of their food are most 

 abundant in such situations. They sometimes live on sandy, 

 muddy, and gravelly bottoms, and are sometimes found adhering 

 to piles of wharves. They are often found between tides, hiding 

 beneath seaweeds or rocks in the tide pools, where they wait 

 until the return of high water to resume their search for bar- 

 nacles or mollusks adhering to the rocks. 



All the species of starfish found in this region have normally 

 five broad rays attached to a central disk (Plate II), although 

 individual specimens having either more or less than this number 

 are by no means rare. This variation in the number of rays is 

 of much interest and is discussed in some detail on page 43. 

 Along the northern coasts of New England lives a species which 

 regularly has six rays and another which has ten ; and in other 

 parts of the world are species in which the number of rays in- 

 creases with the growth of the animal until there may be as 

 many as twenty to forty, or even more. 



The starfishes creep slowly along by means of numerous tube- 

 feet arranged in longitudinal rows on the under side of the rays. 

 They can twist the flexible body and arms into almost every 

 conceivable shape; and, if turned over, they can easily right 

 themselves. 



EXPLANATION OF PLATE II. Skeleton of Starfish, Asterias forbesi. 



(Natural size.) 



Photograph of dried skeleton from aboral surface, showing the reticu- 

 lated skeletal plates bearing conspicuous spines. The skin has been mostly 

 removed. The madreporic plate appears as a circular white spot between 

 the bases of the two lower arms, while the circle of six small spines just 

 to the left of the center of the disk indicates the position of the intestinal 

 opening. 



