Transparent creature called 'sea walnut' discovered that ages in reverse

A transparent sea creature has been newly discovered . Mnemiopsis leidyi, more commonly known as the 'sea walnut', can actually reverse the ageing process.

When it is vulnerable, such as when food is scarce or it is injured, the 'sea walnut' can actually turn back into its larval form, which has two tentacles to catch food, reports Live Science .

That's because when it is in its adult form, it does not have these crucial tentacles.

When it has the food it needs, the 'sea walnut' eventually reaches adult size again and can even regain the ability to reproduce.

According to a study on the preprint database BioRxiv , the 'sea walnut' is the third-known animal species, and the first-known comb jelly (Ctenophora), that can do this.

The other two species are the 'immortal jellyfish' (Turritopsis dohrnii) and the 'dog tapeworm' (Echinococcus granulosus).

Scientists have previously discovered a handful of cnidarians, a group which includes corals, jellyfish and sea anemones, can develop backwards but only before reaching sexual maturity.

While the 'sea walnut' might not appear to look incriminating, it is actually a nuisance.

They are native to the western Atlantic Ocean but have spread to become an invasive nuisance in Europe and Asia.

'Sea walnuts' are understood to have contributed to the collapse of fisheries because they compete with native creatures for food and there isn't enough to go around for all to survive.

They can regenerate entirely from even a small chunk of flesh.

Comb jellies are one of the oldest extant animal lineages and possibly the sister group to all animals.

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