During the day in Lake Constance, the zooplankton D  hyalina departs for the depths where food is scarce and the water cold  D  galeata remains near the warm surface where food is abundant  Even though D  galeata grows and reproduces much faster, its population is often outnumbered by D
hyalina
Predators of zooplankton, such as whitefish and perch, live and feed near the surface of the lake during the day.