The family Delphinidae is the largest in the Cetacean order, and evolved relatively recently, about ten million years ago. There are almost forty species of dolphin in 17 genera all varying in size and shape.
The killer whale or orca (Orcinus orca) is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. Killer whales are found in all oceans, from Arctic and Antarctic regions to tropical seas.
Hah the polar bear wants to eat the killer whale. and he could if the whale was stuck. the polar bear would attack it and kill it by biting around its blowhole. And the killer whale wants to eat the polar bear and it would if the bear fell in.