A NEW AND IMPORTANT COPEPOD HABITAT 



By CHARLES BRANCH WILSON 



State Teachers College, Westfield, Mass. 



In addition to forming an integral portion of the plankton of both 

 fresh and salt water, copepods have also been found in several unique 

 situations. Some species inhabit damp moss in the Black Forest of 

 Germany and other European woodlands long distances from any 

 body of water. Other species live within the branchial chambers of 

 land crabs, which enter the ocean only during their spawning season, 

 once a year. Copepods have also been found in the rain water which 

 accumulates inside the cup formed by the tightly sheathed leaves of 

 certain epiphytic Bromeliads saddled on the limbs of tropical trees 

 far away from the water. But these are simply distribution freaks, 

 likely to occur in any animal or plant group, and confined to so few 

 species as to be worthy only of passing notice. 



There has recently been discovered, however, a new copepod habitat 

 of vastly more importance and claiming as its tenants a sufficient num- 

 ber of genera and species to constitute an important group. According 

 to their habits and mode of life, copepods have hitherto been divided 

 into three well-known groups : free-swimmers, commensals, and para- 

 sites. The dwellers in this new environment will constitute a fourth 

 group, which may be designated as terrac[ueous copepods because they 

 actually live in both water and sand or mud. Brief mention has already 

 been made ' of this group, and the name benthonic was suggested for 

 them. But that term has already come into general use to designate 

 the fauna and flora of the sea bottom as opposed to the plankton. 

 Certain of the free-swimming copepods live close to the bottom and 

 move about in the water or among the vegetation above the bottom. 

 They are the forms which should be designated as benthonic, whereas 

 these terraqueous copepods actually penetrate the sand or mud, and 

 hence can never be captured by towing. They are not free-swimmers, 

 therefore, and are neither commensal nor parasitic in their habits, 

 but must form a new group. 



The discovery of these sand and mud dwellers was first made by 

 the late Dr. X. A. Cobb, government specialist on nematodes. While 



U. S. Nat. Mus. Bull. 158, p. 6, 1932. 



Smithsonian Miscellaneous Collections, Vol. 94, No. 7 



