Sunday, August 28, 2011

What the Fountain of Youth Means to a Jellyfish

Photo from National Geographic
Immortality is the stuff of legend, right? Not for this hydrozoan, the only known animal that can potentially live forever. There's a big catch though: to do so it must repeatedly revert back to an earlier stage through a process known as transdifferentiation. What happens is this: the adult medusa stage of Turritopsis nutricula actually becomes a polyp, kind of like an adult human becoming an embryo. Every cell in its body is changed. In essence it can age backwards and forwards over and over again. No laboratory evidence exists yet to show that this can go on forever, but so far there has been no evidence found that puts an upper limit on the number of times it can happen either.

Illustration from DevBio
Most of the time, of course, they reproduce like any other jellyfish: through the meeting of free floating sperm and egg. But when times are tough the weirdness takes over. Whole colonies can grow from just one backwards-aging medusa.

Times have been tough a lot lately it seems. These oddballs of the deep have been reported from across the world's oceans, far removed from their native Caribbean home. Numbers are spiking worldwide. Don't expect to go to the beach and see rafts of them though. Even a huge Turritopsis is no bigger than a human pinky nail.  And don't confuse immortality with indestructibility. These critters are just as susceptible to death from predation, disease, and bad luck as the next metazoan. They just won't die of old age. Which is, truth be told, very different from the next metazoan.


  1. Well, I learned something! Do you know at which age they revert back?

  2. After they reach sexually maturity is all I know... I think they revert instead of reproducing normally if they are stressed by something in the environment.

  3. Whoa...that is really cool and interesting! Incorporating that into our homeschool lessons this year!

  4. That's so cool, Malea! Sounds like your lesson plan is much more fun than any I had in normal school!


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