Mutualism

Mutualism is a symbiotic relationship in which both species are helped. For example, there is a species of ants that live on a particular type of acacia tree. The ants protect the tree by eating other insects that try to eat the tree. The ants also clear away debris from the tree trunk, which gives it room to grow. In return, the ants receive shelter and nectar from the tree. Another example of mutualism exists between you and bacteria. E. coli provides vitamins for your body, and in return, you provide nutrients and shelter (in your intestines) for the bacteria.