Communities & Ecosystem Sites
Henderson's Dictionary of Biological Terms, by Eleanor Lawrence. 10th Ed.
Predator & Prey Interactions
One form of parasitism is predation. Predation occurs when one species, such as a mountain lion, hunts then kills another species for food, such as a dear. Predation forms the second tier and above for trophic level. In other words, a trophic system could have a primary predator, and a secondary predator. In a freshwater ecosystem, a caddis fly, a herbivore, may be eaten by a primary predator, such as a sunfish. The sunfish itself is preyed upon by freshwater bass, which is a secondary predator, and probably the top predator in this ecosystem.