Starve a Comb Jelly or Injure It and It Dismantles Itself and Becomes a Larva. Then It Grows Back.
A comb jelly called Mnemiopsis leidyi has been spreading across the world's oceans in ship ballast water for decades. It can survive weeks of near-starvation that should kill it. When conditions get bad enough, it dismantles its adult body and becomes a larva again.
Over several weeks, lobes and auricles reabsorb, the animal shrinks into a tentacled larval form with entirely different feeding behavior. When conditions improve and food returns, it matures back into a reproductive adult. Thirteen of 65 test animals completed this full reversal in controlled laboratory conditions. The study was published in PNAS in November 2024.
The only other animal known to reverse development after sexual maturity is Turritopsis dohrnii, the immortal jellyfish — a cnidarian, phylogenetically distant from ctenophores. Two separate branches of the animal tree appear to have independently retained or evolved this capacity. Given that ctenophores are among the earliest animal lineages, the ability may run deeper in the tree of life than assumed.
The molecular mechanism driving the reversal is not yet known. What happens to the nerve net during the transition remains an open question.
Mnemiopsis leidyi can starve, lose a limb, dismantle its own body, and still reboot into a larval state under pressure. Evolution has an answer for nearly every existential threat.
Read the full story at EurekAlert, October 30, 2024
Hot Take: Invasive species managers have spent 30 years trying to contain Mnemiopsis leidyi. When things get hard, the comb jelly reverts to its baby form and starts over. Humans do the same, just with more complaining and snacks.
Subscribe to our newsletter.
Be the first to know - subscribe today
Member discussion