Overview
The Immortal Jellyfish (Turritopsis dohrnii) is a tiny hydrozoan medusa famous in cellular biology as the only known metazoan organism capable of achieving true biological immortality. When confronted with physical trauma, starvation, or aging, this miniature marine invertebrate can revert its adult cells back into their earliest polyp stage via cellular transdifferentiation, effectively resetting its lifecycle indefinitely.
Biology and Physical Characteristics
The adult medusa of Turritopsis dohrnii is bell-shaped and entirely translucent, measuring less than 5 mm across, with a bright red, cruciform stomach visible through its gelatinous umbrella. Mature individuals possess up to 80 to 90 slender marginal tentacles used to entangle micro-zooplankton. Its extraordinary regenerative superpower relies on transdifferentiation, an uncommon cellular process where specialized, differentiated somatic cells (such as muscle or nerve cells) revert into unspecialized stem cells that re-differentiate into a brand-new colonial polyp stolon.
Behavior and Ecology
As a free-swimming medusa, Turritopsis dohrnii pulsates rhythmically through coastal plankton swarms to capture micro-crustaceans with stinging nematocysts. However, when stressed by extreme temperature shifts, water salinity changes, starvation, or physical injury, the jellyfish sinks to the seafloor, absorbs its umbrella and tentacles into a shapeless cyst-like blob, and transforms over 72 hours into a new bottom-dwelling hydroid colony, which subsequently buds off dozens of genetically identical clones.
Conservation and Human Impact
Turritopsis dohrnii is not evaluated by the IUCN, but is exceptionally abundant and expanding globally. By hitching rides in the ballast water tanks of transoceanic container ships, this resilient hydrozoan has established thriving non-native populations in oceans worldwide without causing significant ecological disruption.
Interesting Factoid
When the immortal jellyfish gets sick, starves, or grows old, it doesn’t die—instead, it transforms all of its adult cells back into juvenile stem cells, turning itself back into a baby polyp colony and starting its entire life over again!
Last updated: October 2026