A zebra’s bacteria

Zebra never appear thin, and this has to do with a very special form of “friendship”. A zebra’s digestive system contains 37 different types of bacteria adding up to thousands in total. These bacteria digest what the zebra has eaten and when they die, they transform into protein that is in turn consumed by the zebra. This is known as mutualism. The zebra’s stomach appears bloated because this process of fermentation produces a lot of gas. Without the telling signs of weight loss to determine the health of an animal, the easiest way to see whether a zebra is sick is to look at its mane. If the mane is erect the animal is healthy; if the mane is flopping over to one side the zebra is unwell.