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) symptoms that he was being escorted with, MacKenna is able to rescue his son, only to discover that the first Predator is being hunted by a larger alien of its own kind. The subsequent fighting results in the death of the first Predator, most of the Stargazer staff and the other soldiers in MacKenna's makeshift unit, but MacKenna, Rory and Casey are able to kill the giant Predator and retrieve the original alien's ship. Based on analysis of the ship, they determine that the Predators are adapting themselves with human DNA and intend to take Earth once humanity dies out