The Immortal Jellyfish

It seems like stories of people searching for the fountain of youth have been around forever, and as far as animals go there are certainly plenty with much longer life spans than humans. Koi fish have been known to live over 200 years, at least one Aldabra giant tortoise lived to be 255, and a giant barrel sponge in the Caribbean is estimated to be more than 2,300 years old. However, there may be one animal that is indeed impervious to Father Time; Turritopsis nutricula, the immortal jellyfish.

Photo: Peter Schuchert

All jellyfish go through several life cycles. There are born as larvae that settle onto the sea floor or other underwater structure and develop into polyps, which look similar to a tiny octopus with its tentacles pointed up. The jellyfish buds from this polyp and begins its adult life, feeding constantly and growing quite rapidly. After reaching adult size the jellyfish will spawn, usually dying a short time after. The largest jellyfish live 2-6 months, with smaller varieties only living a matter of weeks.

So, how does the tiny (0.18”) immortal jellyfish manage to live on? The answer is a process called transdifferentiation. After the immortal jellyfish spawns as an adult, it uses this process to transform its cells back into that of an immature polyp, dropping to the sea floor and starting its lifecycle all over again. Some animals such as salamanders can use this process to re-grow limbs, but the immortal jellyfish is the only known animal that can apply transdifferentiation to its whole body, meaning that instead of dying, it becomes a newborn again; and it can repeat this process over and over.

Because these jellyfish are immortal, their population is exploding. Once native only to Caribbean waters, they can now be found in oceans all over the world.