SHARK

Sharks don't have lungs, but they do have to breathe oxygen to survive. Instead of breathing air, though, sharks get oxygen from the water that surrounds them. So they have to move around, if they stop moving for a while, they sink into the water and die, So Sharks have to move and move constantly from birth to death. The same goes for you. If you want to survive, keep moving, then you will be the best hunter... like a shark. (Source: Kakao, translated) — Description from AniList community (anilist.co).