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 macaques in Gibraltar species inhabited the Mediterranean coasts and Europe, reaching as far north as Germany and the British Isles. The species decreased with the arrival of the Ice Age, to extinction in the Iberian Peninsula 30,000 years ago. The Gibraltar Barbary macaques are considered by many to be the top tourist attraction in Gibraltar. The most popular troop is that of Queen's Gate at the Apes' Den, where people can get especially close to the monkeys. They will often approach and sometimes climb onto people, as they are used to human interaction. Nevertheless, they are still wild animals and will bite if