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| 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.
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| 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.
