What is the scientific name of the immortal jellyfish?

The scientific name of the immortal jellyfish is Turritopsis dohrnii. This tiny hydrozoan is famous for its unusual ability to reverse its life cycle after reaching sexual maturity.

When stressed, injured, starving, or aging, an adult medusa can transform back into a juvenile polyp stage. Through transdifferentiation, its specialized cells change into different cell types, allowing a new colony to develop. The process can theoretically repeat indefinitely, which is why the species is called biologically immortal.

That label does not mean individual jellyfish cannot die. Turritopsis dohrnii can still be eaten by predators, succumb to disease, or perish through environmental hazards. Its medusa is only about 4.5 millimeters across, and the species is found in temperate and tropical waters worldwide.

A common mix-up is Turritopsis nutricula. Several Turritopsis species were once grouped under that name, but modern classification identifies the immortal jellyfish specifically as Turritopsis dohrnii. The species was named in honor of Anton Dohrn, founder of the Stazione Zoologica in Naples.