UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 13, No. 5, pp. 123-145 May 5, 1914 



THE VERTICAL DISTRIBUTION AND MOVE- 

 MENTS OF THE SCHIZOPODA OF THE 

 SAN DIEGO REGION 



BY 



CALVIN O. ESTEELY 

 (Contribution from the Laboratory of Scripps Institution for Biolog'ical Research) 



This is one of a series of papers, from the Seripps Institution for 

 Biological Research, that deals with the behavior of plankton organ- 

 isms as indicated by field data. Three publications have already 

 appeared (Michael, 1911, and Esterly, 1912, and Esterly, 1914b) con- 

 cerning the Chaetognatha, Copepoda, and Ctenophora. The facts 

 upon which any conclusions may be based are obtained by first count- 

 ing the individuals of different species in each successful surface and 

 sub-surface haul. The hauls are then arranged according to months, 

 time of day, temperature or salinity, and, since the number of animals 

 taken in each set of hauls is known, it is possible to get some idea of 

 the behavior of the organisms in nature, assuming that relative abund- 

 ance with respect to various factors is a reliable criterion. 



In this paper the surface, vertical closing, and horizontal closing 

 net hauls are dealt with separately and no attempt is made to stand- 

 ardize the catches of one net with those of another for reasons given 

 elsewhere (Esterly, 1912, p. 279). The terms used and explanations 

 given by Michael (1911, p. 112) and by me (Esterly, 1912, p. 282) 

 are applicable here. It is necessary to state, however, that I have not 

 used any Nansen net hauls previous to number 1989 because the 

 attempt was made to pull the net horizontally in those cases, and it 

 seems better simply to omit the hauls from consideration. Further- 

 more, sub-surface hauls between numbers 2151 and 2278 do not enter 

 into the tables because the Schizopoda were removed from the bottles 



