NO. 7 A NEW COPEPOD HABITAT ^WILSON II 



A great deal of motion and very little rest therefore constitutes the 

 essential mode of life of a free-swimmer. 



The great majority of the parasitic copepods, when once they are 

 securely fastened to their hosts, do not move at all but may be, and 

 usually are, carried long distances by their hosts. In early life all 

 these parasitic forms are free-swimmers during their nauplius, met- 

 anauplius, and often their copepodid stages. And of course during 

 those periods they must maintain a great deal of motion and enjoy but 



0.10 



Fig. 8. — Dorsal view of female Cyclopina agilis, a dweller in sandy 

 mud, with large eggs closely appressed to the body. 



little rest. But in adult life this is exactly reversed even for such species 

 as continue to practice more or less the free-swimming of early life. 

 They may leave their hosts and move about freely in the water, but this 

 is not continued for any length of time, and they quickly return to 

 their hosts. 



The commensal copepods spend their entire lives inside the body of 

 their hosts, and hence they never swim freely except in so far as it 

 is possible within such narrow confines. A great deal of rest and 

 very little motion, therefore, are the characteristics of their mode of 

 life. 



