Mutualism is a type of symbiosis that occurs when two unlike organisms live together in a state that is mutually beneficial. It can exist between two animals, between two plants, or between a plant and an animal. Mutualism is unlike the symbiotic state of commensalism in that commensalism is a one-sided state in which a host gives a guest takes, while in mutualism both partners live on a give-and-take basis.
In the African wilds, the zebra and the ostrich enjoy a symbiotic relationship that enhances the ability of each of these large land animals to survive. When the zebra and the ostrich collaborate in their defense by alerting each other to possible danger from an approaching predator, the hunter, such as the lion, is rarely able to capture more than the oldest or feeblest of the herd.
The complementary physical strengths and weaknesses of the ostrich and the zebra allow them to work in coordination to avoid succumbing to the lion. The ostrich possesses great speed and keen eyesight, which enable it to spot large predatory animals long before they are able to position themselves to attack. The zebra, with a running speed equal to that of the ostrich, has excellent hearing and a good sense of smell but lacks the sharp eyesight of the ostrich. When ostriches and zebras intermix for grazing, each animal benefits from the ability of the other to detect approaching danger. If either animal senses danger, both animals are alerted and take off.