Symbiosis. Living Together. Three Types of Symbiosis. Mutualism both species benefit Commensalism one species benefits, the other is unaffected Parasitism one species benefits, the other is harmed. Mutualism. Both organisms benefit from the relationship. Otters and Kelp.
Otters and Kelp
The otters help the kelp by eating the sea urchins which endanger it. The kelp provides and anchor for the otters while they sleep.
The cattle egret and cows
The cattle help the egret who look for grasshoppers and beetles that are raised by the cows. Now and then they sit on the back of a cow, looking for ticks and flies. This does not effect the cattle in any way.
Mistletoe is an aerial parasite that has no roots of its own and lives off the tree that it attaches itself to. Without that tree it would die. It slowly chokes out the life of the host tree.