In the Eastern Pacific, the false killer whale has been known to target smaller dolphins during tuna purse-seine fishing operations; there are cases of attacks on sperm whales (Physeter macrocephalus), and one instance against a calf of a humpback whale (Megaptera novaeangliae). Killer whales are known to prey on the false killer whale, and it also possibly faces a threat from large sharks, though there are no documented instances.[1][2][3][25]