Dolphins have a spindle shaped body, smooth and hairless skin, agile and flexible body, and are good at jumping and diving. They are the fastest moving mammals in water. Having a developed sonar system, it mainly relies on echolocation function during activity, and has excellent hearing in both water and air. The nostrils are located on the top of the head and are used for water and air exchange. Body shape from1Meter length30Kilogram weight (Jurassic dolphin) to9.5Meter length14The weight of the killer whale varies, and their morphological characteristics are also different. Their brain sulci are complex, their memory is good, and they can learn many movements under human training. They are one of the most intelligent animal families, with a gentle, friendly, lively and active personality, and are widely loved by people around the world.