To find out how the immortal jellyfish staves off aging, Maria Pascual-Torner at the University of Oviedo in Spain and her colleagues sequenced its genome – its full set of genetic instructions – and compared it to that of the related but mortal crimson jellyfish (Turritopsis rubra).
They found the immortal jellyfish had twice as many copies of genes associated with DNA repair and protection. These duplicates could produce greater amounts of protective and restorative proteins. The jellyfish also had unique mutations that stunted cell division and prevented telomeres – chromosomes’ protective caps – from deteriorating.
Then, to pinpoint how T. dohrnii reverts into polyp form, the scientists looked at which genes were active during this reverse metamorphosis. They found the jellies silenced developmental genes to return cells to a primordial state and activated other genes that allow the nascent cells to re-specialise once a new medusa buds off. Together, Pascual-Torner says, these genetic alterations shield the animal from the weathering of time.