The immortal jellyfish, Turritopsis dohrnii, has captured global attention due to its astonishing biological capability. This tiny hydrozoan, first discovered in the Mediterranean Sea, possesses the unique ability to completely reverse its life cycle after reaching maturity. This ability to essentially reset its biological clock led to its popular name. A common question is whether this remarkable creature is in danger of extinction. The answer, however, is contrary to what its extraordinary nature might suggest.
The Mechanism of Biological Immortality
The “immortality” of Turritopsis dohrnii is rooted in transdifferentiation, a rare cellular process. This allows the adult medusa form to revert to a juvenile polyp stage when subjected to physical damage, environmental stress, starvation, or old age. Instead, the adult bell and tentacles reabsorb, and the organism settles as a cyst on the seafloor.
Within 24 to 72 hours, the cells of the medusa undergo a transformation, essentially switching their type and function to form a new, genetically identical polyp colony. This cellular reprogramming involves mature, specialized cells converting into undifferentiated stem cells, which then form the structures of the younger life stage. Genomic analysis has shown that this rejuvenation is associated with changes in gene expression and the duplication of genes related to DNA repair and telomere maintenance.
The new polyp colony then buds off new, young medusae, effectively restarting the life cycle. This process can theoretically repeat indefinitely, which is why the species is considered biologically immortal. This ability only prevents death from old age; individuals still succumb to predation, disease, or extreme environmental conditions.
Formal Conservation Status
The central question of whether the immortal jellyfish is endangered can be answered by examining major international conservation lists. The species Turritopsis dohrnii does not have a formal conservation designation from the International Union for Conservation of Nature (IUCN) Red List. It is not classified as Endangered, Threatened, Vulnerable, or Near Threatened.
The lack of a formal listing indicates that the species is not considered to be under threat. The IUCN has yet to assess the immortal jellyfish because its populations are generally robust and widespread. Unlike many species of conservation concern, the immortal jellyfish is not facing a decline in its numbers.
The biological resilience granted by its unique life cycle reversal contributes to its overall stability. This ability to “reset” when conditions become unfavorable helps buffer the species against localized environmental disturbances. Therefore, the species does not meet the criteria for a threatened status based on population decline or restricted range.
Global Range and Ecological Abundance
Far from being endangered, the immortal jellyfish has achieved a cosmopolitan distribution and is considered highly abundant globally. While the species was originally identified in the Mediterranean Sea, it has now spread throughout temperate and tropical waters globally. This rapid expansion is primarily attributed to human activity, specifically the transport of the species via ship ballast water.
The polyp stage, which is attached to surfaces, makes the species an excellent “hitchhiker” on the hulls and in the ballast tanks of ocean-going vessels. This accidental global transit has allowed the jellyfish to establish colonies in new marine environments worldwide, including coastal areas of North America, Japan, and Panama. The species’ hardiness and reproductive strategy—releasing genetically identical medusae from its polyp colonies—further contribute to its ecological success.
In its new habitats, the immortal jellyfish is often classified by scientists as an invasive species. The spread is sometimes described as a “worldwide silent invasion” because the organisms are tiny and their expansion has not caused the dramatic economic or ecological consequences seen with other invasive species. Its resilience and ability to colonize new areas suggest a flourishing population that is unlikely to be considered endangered in the foreseeable future.