The honeyguide bird leading the honey badger to the bees hive, both eat the honey.

A bird building their nest in a tree.

Mistletoe putting its roots into its host tree.

Wolves hunting and eating elk at Yellowstone National Park.

The ants and the acacia tree living together and both receiving benefit.

Orchids growing in tall tropical trees - the trees are not harmed but the orchids get sunlight.

Bees and a flower.

The clownfish and the sea anemone.

Tree frogs using plants for protection.

Lions hunting and eating zebras.

An egret (a bird that eats insects) eats the insects kicked up by a cow as it eats grass.

Head lice living on a human scalp.

An association between two organisms of different species (living closely together). Also called symbiotic relationships.

A common demand by two or more organisms upon a limited supply of a resource; for example, food, water, light, space, mates, nesting sites. It may be intraspecific or interspecific.