A killer whale is a mammal. It is the largest species in the cetacean dolphin family, with a conical head, no protruding beak and black and white body. As a highly socialized animal, it has complex social behaviors, knows hunting skills and can communicate with sound. Its temperament is fierce, good at attacking prey, and it is widely distributed, and it is found in almost all marine areas.

1. Cetacean: Cetacean originated from Artiodactyla and evolved after terrestrial Artiodactyla entered the water 50 million years ago. In order to adapt to the underwater environment, their forelimbs evolved into fins, their hind limbs gradually degenerated, and they grew horizontal caudal fins, and their nostrils moved to the top of their heads.

2. Manatees: Manatees are a special class of marine mammals. They are all herbivorous and usually feed on seaweed and other aquatic plants. There are currently four species. Its body is spindle-shaped, somewhat similar to that of a baby whale, but it has a short neck, a body length of 2.5-4 meters, and a lot of fat under the skin, which can be used to keep its body temperature.

3. Flippers: Flippers are carnivores in aquatic animals, and there are three families, namely sea lions, seals and walruses. Common animals are seals, sea lions, fur seals, walruses, etc. They are similar in appearance, but they are also different. Seals have no outer ears, sea lions have outer ears, and walruses have a pair of fangs.