Collumb, C. J. University of Texas: Marine Science Intitiute, collumb@utmsi.utmsi.utexas.edu
Buskey, E. J. University of Texas: Marine Science Intitiute, buskey@utmsi.utmsi.utexas.edu

 
VISUAL PREDATION ON COPEPODS: EFFECTS OF SIZE, CONTRAST AND BEHAVIOR
 
By being nearly transparent some copepods reduce their visual contrast with the environment. Studies have shown that increases in pigmentation can increase predation on various zooplankton populations. Except for eyespots, copepods tend to contain little pigmentation. However, external egg sacs tend to be heavily pigmented, increasing both the size and contrast of the copepod. Experiments show that juvenile grunt show a clear preference for egg bearing female Dioithonia oculata over males or females without egg sacs. Pigmentation and size differences might not be the only factor effecting this selection. Motion analysis was used to quantify the swimming behavior and escape responses of gravid female, non-gravid female and male Dioithonia. Males show significant behavioral differences from gravid and non-gravid females, but no significant differences between gravid and non-gravid females were measured. Yet there is a significant selection for gravid females over non-gravid females and males, but no selection between males and non-gravid females. This strongly suggests that image size and contrast, not behavioral differences, drive prey selection of the predator. The tendency of this copepod to form dense swarms during daylight hours may help protect gravid females from visual predators.
 
Day: Wednesday, Feb. 3
Time: 04:45 - 05:00pm
Location: Hilton of Santa Fe
 
Code: SS20WE0445H