If we’re going to have creatures that can live forever, why do they have to be these creatures?
Turritopsis dohrnii, a small species of jellyfish native to the Mediterranean, is commonly known as the “immortal jellyfish,” and it literally lives up to its name. Possessing the ability to revert to its a sexually immature stage instead of succumbing to an inevitable death, this tiny creature holds the secret to true biological immortality.
Humans have fantasized about immortality since the beginning of time. We have countless myths and stories about it, but until the mid-1990s we had yet to find any proof that eternal life on this earth was possible. In 1996, researchers published a study about a small species of jellyfish capable of reverting from an adult, solitary individual to its juvenile colonial state, thus cheating death and achieving potential immortality. Just as long as it wasn’t consumed by predators and it could be sustained by its environment, the jellyfish could repeat this cycle indefinitely and live forever. To this day, the immortal jellyfish remains the only known immortal animal.
All right, I’ll bite. How does this work?
Like most other hydrozoans, T. dohrnii begin their life as tiny, free-swimming larvae known as planula. As a planula settles down, it gives rise to a colony of polyps that are attached to the sea-floor. All the polyps and jellyfish arising from a single planula are genetically identical clones. The polyps form into an extensively branched form, which is not commonly seen in most jellyfish. Jellyfish, also known as medusae, then bud off these polyps and continue their life in a free-swimming form, eventually becoming sexually mature. When sexually mature they have been known to prey on other jellyfish species at a rapid pace. If a T. dohrnii jellyfish is exposed to environmental stress or physical assault, or is sick or old, it can revert to the polyp stage, forming a new polyp colony. It does this through the cell development process of transdifferentiation, which alters the differentiated state of the cells and transforms them into new types of cells. Theoretically, this process can go on indefinitely.
If you’re like me, you stop thinking “Ew, jellyfish!” and start wondering about this guy Dohrn for whom it’s named. It’s this guy:
Felix Anton Dohrn (1840–1909) was a prominent German Darwinist and the founder and first director of the first zoological research station in the world, the Stazione Zoologica in Naples, Italy.
Give that man an immortal namesake!