From the classification point of view, killer whale belongs to the genus killer whale of Dolphinidae, so it belongs to dolphin in a broad sense, but it is still different from dolphin known by people. Dolphins belong to cetaceans, so killer whales are also whales. However, people usually call the larger ones of cetaceans whales and the smaller ones dolphins. Although killer whales are much larger than dolphins, they are still smaller than other relatives of cetaceans. In addition, dolphins have an ability that other whales don't have, that is, echolocation.

1. Killer whales: Killer whales are also called killer whales. Although this title sounds terrible, there are no examples of wild killer whales eating people. It is the largest species in Dolphinidae, and its body color is mainly black and white. It mainly lives in polar or temperate waters, and prefers underwater environment 20-60 meters deep.

2. Small killer whale: Small killer whale is also called Jurassic killer whale. It is related to killer whale, but it is an independent species, not a juvenile form of killer whale. It is widely distributed, and its footprints can be found in any tropical or subtropical sea area. If you see a whale population less than 50, it may be this species.

3. Pseudo-killer whale: Pseudo-killer whale is the third largest species of dolphin family, similar in shape to killer whale, but slightly smaller than killer whale. In addition, its body is black, unlike killer whales, which are black and white. It is also widely distributed, and can be seen in other oceans except the Arctic Ocean.

4. Melon whale: Melon whale is somewhat similar to Jurassic killer whale, but it has more teeth, a thicker body and a small or no beak. This is a highly populated cetacean, which usually gathers in hundreds and thousands, and belongs to a deep sea species.

5. Pilot whale: Pilot whale is also called mega whale, which is a very timid whale. It is 5-meter long and mainly lives in temperate waters.