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
Predator (fictional species) "Predator" series, where a number interfere in an East African civil war, coming into conflict with both humans and their Hunter counterparts. By the time of "Three World War" the Killers are assumed to have been wiped out by the Hunters, but some survive and begin attacking human colonies, forcing Noguchi to forge an alliance between humans and the Hunters in order to deal with them. In John Shirley's stand alone novel "Predator: Forever Midnight", Predators, now referred to as "Hish," are shown to possess a gland located between their neck and collarbone which secretes powerful hormones into their bloodstream