The ancients always thought that whales were a kind of fish. In fact, they are mammals. Most of them live in shallow water, and some species live in fresh water. In order to live underwater, the forelimbs of whales evolved into fins, and the hind limbs degenerated, giving birth to caudal fins. Noses grow on the head, and they need to come out of the water to breathe air every once in a while. However, their hearing is very good and they can hear very small sounds. In order to live in water conveniently, the physiology and structure of whales have undergone tremendous changes. The whale's body structure and living habits are obviously different from those of any mammal, so it has been listed as a single item for a long time.
Kunpeng's name comes from the book Xiaoyao Shuo. In ancient times, it was the North Sea in the Northern Ghost, which was equivalent to a very far place. I thought Kun Peng was a big fish, that is, a big fish in the North Sea. Now the big fish in the sea is a whale. In other words, Kun Peng was a whale in the eyes of the ancients. It's a little unreal, but it is. It gives people a mysterious feeling, but in fact, the ancients were really smart, and it was really not easy to find these wonderful creatures without investigation.
From the fish in the north to Kun and learning pigeons, it is also amazing in the records of Zhuangzi's free and unfettered theory. Everything changes, everything changes. In appearance, Kun has dorsal fin and seems to be closer to fish. No wonder the ancients thought it was a big fish, but they didn't know it was a whale, and they swam very fast, which should also prove that sentence.