This Immortal Jellyfish Can Age Backward and Start Over Again

Image: Bachware/ Wikimedia Commons

It’s eluded humans so far, but the secret to immortality may lie in the hands — no, tentacles — of one species of jellyfish commonly found in the Mediterranean Sea.

The Turritopsis dohrnii or “immortal jellyfish” is smaller than a fingernail and has a clearly visible bright-red stomach. But the fascinating part is its ability to extend its lifecycle: The tiny jellyfish grows into a fully formed adult and then instead of dying, it can revert to an immature stage – starting the process all over again!

Jellyfish start out as small larvae, which settle onto the seafloor and form a colony of polyps. The polyps eventually develop into genetically identical jellyfish that detach and become free-swimming sexually mature adults in a few weeks.

If the immortal adults become sick or injured, they can go back to their polyp state and start the development cycle anew.


In theory, they can do this indefinitely, but the behavior has only been observed in labs so there’s still a lot we don’t know. Plus, the jellyfish can still die in the wild if they are eaten by predators or ravaged by disease before they can revert completely.

The jellyfish revert by altering their cells in a rare process called transdifferentiation — basically, cells specialized for one thing are transformed into new cells with a completely different specialty. Researchers still don’t know much about the species, but the process could have potential applications for human medicine.