The tiny hydrozoan Turritopsis dohrnii, widely known as the immortal jellyfish, possesses a unique biological superpower: it can reverse its life cycle from a sexually mature medusa back to a juvenile colonial polyp. When subjected to extreme physiological stress—such as starvation, sudden temperature shifts, or physical trauma—the jellyfish bypasses normal biological senescence through a process known as cellular transdifferentiation. During transdifferentiation, specialized adult cells, such as striated muscle or epidermal tissue, lose their distinct cellular identities and regress into unspecialized stem-like cells.
These reprogrammed cells then re-differentiate into entirely new tissue types required to form a juvenile polyp cyst. Within days, the cyst grounds itself onto a substrate and grows into a fresh polyp colony, which eventually buds off genetically identical, cloned medusae. Unlike simple tissue regeneration, this cycle allows the individual to reset its developmental clock indefinitely.
Researchers studying T. dohrnii seek to decode the underlying genomic regulators, non-coding RNAs, and DNA repair mechanisms responsible for this plasticity, hoping to discover pathways relevant to human regenerative medicine and cellular aging.