1907] J cnnings.— Behavior of the Starfisli. 95 



starfish produces thousands of young-; these fall upon all sorts 

 of conditions, favorable and unfavorable. Those which fall upon 

 decidedly unfavorable conditions never become adults, so that, 

 of course, we do not find adult starfish under such conditions. 

 But we can place the starfish under unfavorable conditions, and 

 through changes in the environment this often happens in nature. 

 If now the starfish made no movements it would soon die. The 

 movements are clearly of such a character, on the whole, as to 

 help the starfish to avoid unfavorable conditions and to find 

 favorable ones. 



When the starfish is undisturbed in the natural conditions 

 that are throughout favorable to its life proces.ses, — under a 

 stone, protected from the waves and the light, with plenty of 

 oxygen and food, — it keeps rather quiet. Only as it begins to lack 

 food or other necessary things does it move about. 



Exploratory Movements. — But if the starfish is removed to 

 a new situation, or if it is disturbed in almost any way, — as for 

 example when it is removed from the large tank to a small one 

 that serves for observation, — it soon begins to move, and usually 

 spends a long time exploring and feeling about. Two or three 

 rays are raised from the bottom and swing first in one direction, 

 then in another, waving about in the water, as if searching for 

 some object. Meanwhile with the other rays the starfish is creep- 

 ing about as rapidly as it can. On the rays that are "feeling 

 about" the tube feet are extended, — especially at the tip, but 

 also elsewhere; — these are likewise performing "feeling" move- 

 ments, waving about from side to side and exploring all the 

 region which they can reach. A starfish placed in a jar of water 

 on the observation table usually soon explores the entire vessel 

 in every part, essays climbing out of it here and there, and be- 

 comes as it were acquainted with everything to be found in the 

 region, before it settles down. Such active exploration usually 

 lasts half to three-quarters of an hour before the animal comes to 

 rest. And after a short period of rest the animal often begins 

 exploring again, though usually it does not continue so long as at 

 first. 



It is evident that these exploratory movements may be of 

 great use to the animal in a region which it has not before ex- 



