A keystone species is a species that plays a particularly important part in maintaining the balance of an ecosystem. A keystone species may consist of only a small part of that ecosystem but serves some vital role necessary for ecological equilibrium to exist. When a keystone species goes extinct or disappears from its natural habitat it can easily lead to a domino effect of extinctions and the ecological collapse of that system. This is due to the fact that native species of an area are often dependent on a specific service provided by the keystone species. Therefore, extinction of keystone species plays a significant role in the declining biodiversity of the planet. To demonstrate the importance of keystone species we will look at the environmental and ecological effects of the depletion of three keystone species: earthworms, jaguars and otters.