CHAPTER XIII 



THE STARFISH AND ITS ALLIES 



Systematic Position. The starfishes belong to the 

 group of Echinodermata, 1 characterized by a radial, usually 

 five-rayed, structure, a more or less well-developed system 

 of calcareous plates in the skin ; a system of water-tubes, 

 which is used by the movable forms for locomotion; and 

 the separation of the intestine from the body cavity. 



Distribution and Habitat. The common pink starfish of 

 the eastern United States (Asterias 2 vulc/aris 3 ) ranges 

 from Labrador to northern Florida. A dark brown form, 

 sometimes called Asterias Forbesii^ is recognized by some 

 authors as a separate species inhabiting the coast from 

 Massachusetts Bay southward. Our shore starfish extends 

 out into fairly deep water, but is not abundant at greater 

 depths than 60 fathoms. In Long Island Sound it is 

 found especially on. the oyster beds, where it is very 

 destructive. On rocky coasts starfishes will be found in 

 crevices of the rock or in tide-pools. They love cool 

 waters, and are often found hanging on vertical walls or 

 ledges. Upon reaching the surface of quiet water, they 

 may extend one or more of their arms out upon the under 

 side of the surface film. 



hedgehog, sea-urchin ; Se'p/xa, skin. A key to the principal 

 classes of Echinodermata will be found in the Appendix to this Chapter. 

 - dcrT^p, star ; dtrrepias, starred. 



3 Common. 4 Of Forbes, an English zoologist. 



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