THE BEHAVIOR OF A PARASITIC COPEPOD 



43 



the long axis of the body. By means of these antennae the 

 copepod is enabled to cling to the sides of the dish or to sus- 

 pend itself from the surface film. In the latter case, surface 

 tension undoubtedly plays the important role in maintaining 

 the animal. Parker (1901), has observed similar behavior in 

 the marine copepod Labidocera aestiva. He concluded that the 

 antennae serve as means of attaching the copepod to fixed objects 

 or to the water film. My observations are in accord with his. 

 The peculiar spiral movement of the copepod is of great sig- 

 nificance. Many of the Protozoans and Rotifers have for a 

 long time been known to move in this way. Jennings, more 

 than any other investigator, has made a careful study of the 



Figure 5. Normal movements of larva. 



problem, and has shown that a spiral path is of great adaptive 

 value to the lower organisms. He has found (1901, '04, '06) 

 that most of the Infusorians, especially the "hunter ciliates, " 

 move in a spiral course. In his work on Paramecium we get 

 a thorough analysis of this type of locomotion. Discussing 

 the adaptiveness of this movement, Jennings says: 



'The problem solved by the spiral path is as follows: How 

 is an unsymmetrical organism, without eyes or other sense 

 organs that may guide it by the position of objects at a dis- 

 tance, to maintain a definite course through the trackless water, 

 where it may vary from the path to the right or to the left, or 

 up or down, or in any intermediate direction ? It is well known 

 that man does not succeed in maintaining a course under similar 



