Predator and prey populations affect one another through density-dependent feedback. Snowshoe hare and lynx cycles show how changes in each population can occur with a time lag.
The shore crab (Carcinus maenas) forages for food in the intertidal zone on rocky seashores. An experiment was carried out to assess predation at specified levels of food abundance. An area of shore was enclosed in a wire cage. All other food was removed from the encaged area except the mussels provided by the investigators. The number of mussels consumed was measured while the crabs foraged at densities of one, two or four crabs per cage.
Suggest a reason for the plateau in the graph when only one crab is present in the cage.
Determine whether foraging by crabs is dependent on number of prey (mussels) or number of predators (crabs).