Symbiotic partnership.
This word means living close together.
This is a very close and a mutually beneficial relationship between two different organisms.
Lichen is a symbiosis of two different organisms – a fungus and an algae.
Parasitic partnership.
A close but one sided relationship where one partner benefits and the other loses.
One organism battens onto and lives off the other partner. It harms its host in this process.
Flat worms thrive in the blood vessels of their human hosts.
Commensalism.
A close one sided relationship in which one partner gains but not at the cost of the other partner – as
in the case of parasites.
The cattle egret lives off the parasites found on the back of the cattle and the other grazing animals.
But the cattle are not harmed in anyway.
Epizoic partnership.
A close relationship in which one partner lives on the skin of the other and is either carried or towed
by it. The remora fish is a good example.
It attaches itself onto a larger fish by means of a suction disc on its head.
Amazing Animal Kingdom 