SEA SLUG SPECIES THAT CAN DECAPITATE SELF, REGROW ENTIRE BODY FOUND

Scientists in Japan have discovered that a species of sea slug can decapitate itself and then regrow an entirely new body, complete with a beating heart and other vital organs, The Guardian reported.

The process, from shedding all of itself below the neck to regrowing a new body, took less than a month, in an extreme example of a process known as autotomy. Sayaka Mitoh, of Nara Women’s University, said: “We were surprised to see the head moving just after autotomy.”

As reported in the journal Cell Biology, Mitoh and colleague Yoichi Yusa wrote how, in their studies of the life history of the sea slugs, they spotted something odd. Three of the younger lab-raised sea slugs, and one wild specimen being reared, “autotomized at their neck position” leaving behind a body with its heart, kidney, intestine and most of the reproductive organs.

The scientists think the sea slugs may have developed the technique as a way of getting rid of a parasite in their body. Another key part of the trick is finding a way to get energy when you don’t have a digestive system.

The scientists think the sea slugs are using the energy from the photosynthesis occurring in cells that they’ve gained from algae they’ve eaten.

“I call them solar-powered slugs,” said Prof Maria Byrne, of the University of Sydney, who was not involved in the research.

Byrne is a marine biologist who has studied autotomy in starfish, also known as sea stars. She said some sea star species are able to regrow a new central nervous system, regenerate a new body from a severed arm, or even split themselves in half to colonize a habitat. Sea slugs being able to regrow a full body was “kind of remarkable,” she said, and the ability was likely linked to the presence of stem cells.

“Stem cells are in all invertebrate animals. It’s a common mechanism, but it’s lost in higher animals,” she said. Other animals that can regenerate body parts include salamanders that can regrow their full tails, axolotls (colloquially known as Mexican walking fish) that can regrow limbs and some fish that can regrow vital organs.

Writing for the Associated Press (AP) on March 9, 2021, Seth Borenstein and Mayuko Ono stressed humans may be able to learn something useful from the sea creatures. What’s especially intriguing is that these sea slugs are more complex than flatworms or other species that are known to regenerate, said Nicholas Curtis, a biology professor at Ave Maria University who wasn’t part of the study.

“It is, of course, a wonder of nature, but understanding the underlying molecular mechanisms involved could help us to understand how our cells and tissues can be used to repair damage,” Curtis said in an email.

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