What do parasitism, predation, and commensalism have in common? How are they different?

Question

joel_the_boss · Answer

Here are definitions of a few of the most common words used by biologists to classify such inter-relationships. • Symbiosis: This comes from a Greek word simply meaning 'living together' and can be used to describe any association between two organisms. • Mutualism: This can be used to describe an association in which both organisms apparently benefit • Commensalism: In this association one organism [the commensal] benefits, and the other [the host] is apparently unaffected. • Parasitism In this association one organism [the parasite] benefits, and the other [the host] is adversely affected [weakened, sickened, damaged etc]. This description would also fit the relationship between a carnivore and its live prey and a herbivore and the plant it feeds on, especially if they are very specialized in the food they eat. We normally define parasites as orgamisms which cannot survive without their host and have special modifications to their body or their life cycle for this association. In many ways though, the difference between a lion eating a gazelle and a flea feeding on a dog, is a matter of relative size. Resources: http://www.seaslugforum.net/find/symbio