Reason 1: Dolphins often play, play and jump in groups on the sea. Reason 2: Dolphins jump to reduce water resistance. Reason 3: Dolphins always surface to get rid of parasites. Reason 4: Dolphins evolved from land animals. They breathe with their lungs and come out of the water to breathe. Dolphin, a general term for a class of aquatic mammals of the dolphin family, is a small or medium-sized toothed whale. It usually likes to live in groups and prey on fish, squid, etc.
Dolphins widely live in the world's oceans. They are also distributed in the brackish water near the inland sea and river inlets. Some species are found in inland rivers.
Porpoise family differentiated from Miocene about 10 million years ago. There are 17 genera and nearly 40 species. It is the largest family of cetaceans. It has a strong and flexible body and is good at jumping and diving. （WeiShenMeHaiTunZongShiShiBuShiFuShangShuiMian?）