1^07] Jennings. — Behavior of the Starfish. 59 



species, Asterias {Coscinasterias) forreri de LorioP, was selected 

 for special study. Nothing has been published heretofore on 

 the habits and behavior of this species. 



Asterias forreri is found on the under side of rocks, just be- 

 low the tide level. It clings closely to the rock, and usually 

 moves little or not at all while under the observation of the curi- 

 ous, so that at first there appears to be little behavior to study. 



How does such a creature manage to succeed in the struggle 

 for existence? How does it get material to keep up the processes 

 of metabolism '? How does it happen to remain under such con- 

 ditions as enable the life processes to continue in the midst of 

 thousands of agencies that are acting against these? By taking 

 up the behavior from this standpoint we shall be able to weld 

 what might be mere scattered observations, into a connected 

 whole. At the same time this will perhaps give us some insight 

 into the complex life of the sea-shore and the manifold inter- 

 relations of its inhabitants. 



Respiration and its Protection by the Pediceli.ariae. 



The first of the life processes which we shall take up is that 

 of respiration. The starfish, like man and Amoeba, must have 

 pure oxygen, or its life processes stop. If left in water that is 

 not aerated, it dies in a few hours. How does the starfish get 

 its oxygen? 



The body of the starfish is protected by a basket-Avork skele- 

 ton of lime, which bears over its upper surface many short 

 spines. Between the meshes of the basket-work there are holes, 

 which are covered in the living starfish by a delicate membrane. 

 If in the living animal we examine the surface between the 

 spines, we find these little patches of membrane covered by many 

 small finger-like processes (fig. 1 g.) These processes, of which 

 each starfish bears many hundreds, are the gills of the animal. 

 They are hollow and have very thin walls. Their internal cavity 

 opens into the body cavity of the starfish, which is filled by a 

 colorless fluid. This fluid circulates within the finger-like gills, 

 passing up one side to the tip, and down the other. This circula- 

 - Kindly deterininea for iiic liy Dr. Hubert Lyman Clark. 



