Angels, vampires, and fairies are just a few things we think of whenever the word “immortal” comes up. These creatures live forever, yet they are also always labeled under the ‘fiction’ category. At this point, our idea of immortality, or living forever, also correlates to ‘make-believe’ and fabricated animals. However, an accidental discovery in the 1980s on a certain jellyfish changed this common idea of immortality: the jellyfish Turritopsis dohrnii has been found be able to live forever.
Are They Really Immortal?
By definition, being immortal means that the creature can live forever and never die or decay. In this case, the Turritopsis dohrnii isn’t truly immortal; they still have predators that could eat them, and they can be killed in other ways. However, this species has a unique life cycle that makes them, in theory, able to live forever.
The Circle of Life
Most jellyfish life cycle begins with a fertilised egg. This egg grows into a planula, the first larva stage. The planula latches on to a surface, like a rock, and develops into a polyp. This is a tube-shaped structure with a mouth in one end, and a kind of ‘foot’ at the other. Overtime, the polyp grows into little colonies of more polyp that share feeding tubes with one another. Eventually, one of these colonies forms a bud, which creates pieces that stack on on top of each other. These pieces are then able to break away from the stack, starting the next stages of the life cycle: the separated pieces form into an ephyra, a small jellyfish, and then the medusa, the fully-formed adult jellyfish.
The End…Or Beginning?
Normally, the medusa would be the final stage of a jellyfish’s life cycle. However, the Turritopsis dohrnii, has an additional ‘hidden power’: during a dangerous situation, like starvation of injury, this jellyfish species can regress back to its first larva stage, the polyp, and start over its life cycle. In comparison, this ability is kind of like a frog turning back into a tadpole, or a butterfly changing back to a caterpillar.
There has been some research showing that the Turritopsis dohrnii isn’t the only jellyfish species with this ability. The jellyfish Aurelia aurita, or moon jelly, has also been found to age regress. Perhaps this kind of immortality wasn’t exactly what you had in mind, but it’s still incredibly fascinating. Arguably, this could be even cooler than simply living forever. Imagine if you had the ability to turn back to the age of 7… it’s like living multiple lives in one lifetime!