Definition and examples

The symbiosis (Greek means "living together") refers to the interaction of two or more different species, combined with a mutual advantage in terms of biological fitness, probability of survival or improved metabolism. Therefore, both organisms benefit from the relationship; in contrast to parasitism, where only one species benefits, while the other species is damaged.
Each symbiosis can be grouped by intensity / extent / dependency into one of three groups:
allianceBoth species have the advantage of occasional collaborations, but are not dependent on them and could survive on their own without symbiosis. (for example, symbiosis between the woodchuck and larger wild animals)
mutualism: Regular symbiosis, without having to survive for the species. (e.g., symbiosis between ant and aphid)
Eusymbiose: The individual symbionts alone are no longer viable without their symbiosis partner. A reciprocal relationship is imperative to survive. (e.g., lichens -> symbiosis between fungus and algae)
The process of coevolution can explain how rather loose alliances, for a long time a mutualistic symbiosis, up to an eusymbiosis arises. In the course of evolution, both organisms have adapted to each other so mutually that they can no longer exist alone without their co-partner.

Examples of symbioses

Examples of symbiosis between different organisms:
Ant and aphidSome ant species "milk" aphids and use these excrements (honeydew) as food. In return, the ants guard the Blattldeuse from predators.
Ant and mushroomLeafcutter ants feed on a special fungus that they breed and care for themselves with chewed leaves.
Clownfish and sea anemone: The clownfish finds shelter in the sea anemone from its predators and protects the sea anemone from its predators. Both species have specific enemies.
Madenhacker: The bird species picks parasites of large wild animals (buffalo, rhino, zebra). The wild animal loses its damaging parasites and the venison hacker receives food.
weave: Symbiosis of alga and fungus; Algae can not survive on land; the mushrooms provide water and nutrients; in return, the alga operates photosynthesis
intestinal flora: Man supplies the intestinal bacteria with food, but food components are broken down and made usable for the body.
mycorrhizal: Symbiosis between plants and fungus. The fungus is located at the roots and provides for an improved absorption of nutrients from the soil. In return, the plant provides carbohydrates.