dolphin

Dolphin is a general term for a class of aquatic mammals. It is a small or medium-sized toothed whale. It lives widely in all oceans of the world. It is also distributed in inland seas and brackish water near river estuaries. Some species are found in inland rivers. Usually like to live in groups, prey on fish, squid and so on.
Dolphins have a spindle-shaped torso, smooth and hairless skin, strong and flexible body, and are good at jumping and diving. They are the fastest mammals in water. With a developed sonar system, it mainly relies on echolocation function during activities, and has excellent hearing in water and air. The nostrils are on the top of the head and are used for exhaling water and exhaling air. The body size varies from 1 meter long and 30 kilograms (pygmy dolphin) to 9.5 meters long and 14 tons (killer whale), and the morphological characteristics are also different. They have complex brain grooves, good memory, and can learn many actions under human training. They are one of the animal families with the highest IQ. They have gentle, friendly, lively and active personalities, and are generally loved by people all over the world.