Many factors can stabilize predator and prey populations. Following changes in both predator and prey communities, Asiatic lions shifted their predation patterns. This incidental catch undermines ecosystem stability, depleting stocks of important predator and prey species. No matchup between predator and prey has ever been more dramatic. There is a positive correlation between the size of a predator and its prey. Its only natural predator is the killer whale. The American alligator is the only known natural predator of the panther. Venom is used as a chemical weapon by predator species. The saltwater crocodile is a large and opportunistic hypercarnivorous apex predator. The model chosen varies with the octopus's predator and habitat. These may serve to warn the animal of an approaching predator. One possible predator of gorillas is the leopard. The Nile crocodile is a strong example of an apex predator. The sperm whale is the largest toothed predator on earth. The leopard is the main natural predator of the okapi.