A symbiotic relationship is one where two organisms live together in a close, often permanent association. The term is often used to describe relationships between animals, but can also refer to plants, fungi, and bacteria. There are three main types of symbiotic relationships: mutualism, commensalism, and parasitism.
In mutualism, both partners benefit from the relationship. One example of mutualistic symbiosis is the partnership between some species of ants and certain kinds of trees. The ants protect the trees from herbivores (such as caterpillars) by attacking them when they try to eat the leaves. In return, the trees provide food and shelter for the ants in the form of nectar-filled flowers and hollow stems.
Commensalism is a type of symbiosis in which one partner benefits while the other remains unaffected. One example of commensalism is the relationship between cattle and cattle egrets. Cattle egrets follow herds of cattle around and eat insects that are stirred up by the cows’ hooves. The cows are not affected by this arrangement; they neither gain nor lose anything from it.
Parasitism is a type of symbiosis in which one organism lives off another organism at its expense. Fleas are parasitic on mice; they live on their blood and cause them irritation and discomfort. However, not all parasites kill their hosts – many merely weaken them or make them more susceptible to disease