1. Dolphin is the name of the whole mammal dolphin, which is small or neutral and widely distributed. It can be seen in all major sea areas and near some inland seas and estuaries. Very few species will live in inland rivers and generally live in groups to prey on fish and shrimp. The evolutionary history of dolphins can be traced back to 6.5438+million years ago, and * * * has always existed.
2. Dolphins are smooth and hairless, and flexible. They are very good at jumping and swimming. They are also the fastest mammals in the water. They have very smart brains and developed sonar. When they are active, they all rely on the sound waves emitted by sonar for echo location. They have good hearing in water and air. Dolphins' nostrils are long on their heads, which is convenient for getting out of the water for air. The smallest dolphin is about one meter long and weighs about 30 kilograms. The largest dolphin is nearly 10 meter long and weighs 14 ton. Every dolphin has different morphological characteristics. The brain is very developed and the memory is amazing. When training dolphins, humans will make many difficult moves, with high IQ and friendly personality. Many people like dolphins.
3. There are three kinds of finless porpoises, most of which are distributed in coastal areas and rarely live in rivers. Compared with dolphins, finless porpoise has a smaller body, a round head, similar jaw length, smaller teeth, small eyes and no dorsal fin. Mainly feed on some fish and shrimp, and will migrate back and forth with the change of living environment. It swims flexibly in the water, likes deep diving and is often exposed.