Sea Creature That Reverts to Baby Form is Essentially Time-Traveling

A recent study has revealed that a sea creature, the Atlantic comb jelly, also known as the “sea walnut,” has the remarkable ability to reverse its aging process. When faced with a lack of food or injury, this gelatinous invertebrate can revert to its larval form, a stage in its life where it possesses tentacles to catch food.

In its adult form, the sea walnut resembles a small, transparent pair of lungs and lacks these tentacles. The study, which is yet to be peer-reviewed, suggests that the sea walnut (Mnemiopsis leidyi) is only the third known animal species, and the first known comb jelly, capable of returning to an earlier stage of life after reaching adulthood.

While some jellyfish, sea anemones, and corals can also revert to an earlier physical form, they can only do so before reaching sexual maturity. The other two species known to reverse aging in adulthood are the “immortal jellyfish” (Turritopsis dohrnii) and the dog tapeworm (Echinococcus granulosus).

The researchers stated that this discovery “confirms that developmental reversal might be more widespread than previously thought.”

 

The Study of Sea Walnuts

The sea walnut is originally from the western Atlantic Ocean but has spread to other regions, becoming an invasive species in parts of Europe and Asia. It is now present in the Black, Caspian, Mediterranean, Baltic, and North Seas.

The sea walnut’s ability to survive without food for extended periods, such as when trapped in the ballast water of ships, is believed to be how it reached distant shores.

To better understand this survival mechanism, scientists conducted an experiment where they starved one group of comb jellies and physically injured another by removing tissue from their lobes. Instead of dying, the sea walnuts shrank into small, blob-like forms.

When the jellies were later fed, 13 of the 65 comb jellies grew tentacles, signaling that they had reverted to their larval stage. Eventually, they regrew their original size and lobes and were even able to reproduce again, according to the study.