Keystone species mussel population explodes uncontrollably, driving out most other species. These creatures need not be apex predators. Sea stars are prey for sharks, rays, and sea anemones. Sea otters are prey for orca. The jaguar, whose numbers in Central and South America have been classified as near threatened, acts as a keystone predator by its widely varied diet, helping to balance the mammalian jungle ecosystem with its consumption of 87 different species of prey. The lion is another keystone species. Keystone mutualists are organisms that participate in mutually beneficial interaction and the loss of which would have a profound impact upon
Barbary macaque primarily of plants and insects and they are found in a variety of habitats. Males live to around 25 years old while females may live up to 30 years. Besides humans, they are the only free-living primates in Europe. Although the species is commonly referred to as the "Barbary ape", the Barbary macaque is actually a true monkey. Its name refers to the Barbary Coast of North West Africa. The Barbary macaque population of Gibraltar is the only such population outside Northern Africa and the only population of wild monkeys in Europe. About 230 macaques live on the Rock of