CHAPTER VII 



ECHINODERMATA 

 ASTEROIDEA 



A STARFISH 



Several species of starfishes are common along our coasts, 

 the most familiar being Asterias vulgaris, the common New 

 England form, which is found along the entire Atlantic coast, 

 and Asterias forbsii, which- is found south of Cape Cod. 

 They are remarkably sluggish creatures which live on the sea 

 bottom, moving slowly, often in large numbers, from place to 

 place and feeding on the various mollusks which come in 

 their way. 



Two specimens will be needed for this dissection, a dried one 

 for the study of the hard parts, and one that is fresh or has 

 been preserved in formalin or alcohol for the study of the inter- 

 nal and other soft parts. To prepare a dried starfish the live 

 animal should be placed in fresh water for half an hour. It 

 should then be placed in alcohol for an hour, and then dried 

 thoroughly. If only preserved material be at hand the animals 

 may be simply dried. The fresh water and alcohol expand the 

 body-wall of the animals and prevent it from collapsing after 

 death. 



Study the external characters of a fresh or a preserved speci- 

 men. Observe the color and the flattened radiate body-form. 

 The body is composed of a central disc from which radiate five 

 arms or rays. All of these rays are normally of equal length. 

 Specimens are often found, however, in which the length of 



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