7. Immortal jellyfish

The next entry on our list of the longest-living animals should surprise you. Turritopsis dohrinni, also known as the immortal jellyfish, is a rare jellyfish species that may be the only animal in the world to have really discovered the fountain of youth. In fact, it may be the only species with no limit to its lifespan.

These jellyfish are found mostly in the Mediterranean, and they start life as larvae. They eventually transform into polyps on the seafloor. Here comes the interesting part: these polyps produce free-swimming medusas, or jellyfish.

A mature immortal jellyfish can turn back into its initial stage of a polyp if it is starving or physically damaged. This allows them to go back to an earlier life stage to start life again. It’s pretty impressive how Mother Nature works, isn’t it?

When a mature Turritopsis dies, it will start to decay on the ocean floor. Its cells then reaggregate back into polyps, producing new jellyfish, hence the name “immortal”.