Aging in jellyfish

There is no biological law that says aging is inevitable, and many organisms in fact do not age. An organism is said to achieve negligible senescence if there is a negligible increase in the probability of death with the passage of time. For example, the naked mole rat achieves negligible senescence by maintaining a constant 5% mortality each year, with death affecting the aged and young non-queen mole rats with equal probability. The hydrozoan Turritopsis dohrnii achieves negligible senescence in a unique way - it is the only known species able to rejuvenate repeatedly after sexual reproduction.

The ‘immortal’ jellyfish Turritopsis dohrnii appears to achieve biological immortality through cycles of epigenetic rejuvenation involving the PRC2 complex that silences developmental genes.

Comparative genomics of mortal and immortal cnidarians unveils novel keys behind rejuvenation

Maria Pascual-Torner, Carlos López-Otín, et al., 2022, PNAS