Turritopsis dohrnii is a small species of jellyfish that is native to the Mediterranean and more commonly known as immortal jellyfish. It actually does live up to its name since it has the ability to revert to its sexually immature stage instead of passing away. In short, this small creature has the secret to immortality – in all biological senses.
It was in 1996 that researchers published a study about the immortal jellyfish that could revert from an adult and solitary individual to its juvenile colonial state. This helped the immortal jellyfish to escape death time and again, thus allowing it to achieve immortality as long as it wasn’t consumed by predators and could be sustained by its environment.
All known kinds of jellyfish exist in two forms; polyp form and medusa form. However, most of the jellyfish grow from their polyp form to medusa form before reaching the end of their life cycle and dying. Turritopis dohrnii or the immortal jellyfish has the ability to switch between the two stages and by doing so; cheat death. It carries out a process that is known as transdifferentiation that involves the transformation of a mature cell into another kind of mature cell.
Instead of embracing death like other creatures, this small immortal jellyfish retracts its tentacles and turns into a blob before dropping to the ocean floor and reverting to its polyp stage within three days. Scientists have discovered that the new polyp is actually genetically identical to the original jellyfish but a juvenile version of it. You can consider this as a chicken reverting to an egg!
Interestingly though, the immortal jellyfish is not in complete control of the reversal from medusa to polyp form. Research has indicated that this transformation can only take place when the jellyfish has been injured or is starving. It can also occur when the temperature or salinity of the water that it resides in changes. The cycle can be repeated indefinitely though if the conditions are right.