Some sea slugs can decapitate themselves and then regrow an entirely new body, it’s been found.
Researchers in Japan stumbled across the revelation while studying two species of sacoglossan sea slugs.
They found a slug could decapitate itself and then regrow an entirely new body, complete with a heart and other organs in an extreme version of the process known as autotomy.
In a study, which was published in Current Biology on Tuesday, author Sayaka Mitoh said: We were surprised to see the head moving just after autotomy.
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Scientists have discovered that some Japanese sea slugs can grow whole new bodies if their heads are cut off, taking regeneration to the most extreme levels ever seen.
The researchers found that the head of the decapitated slug kept living, and began feeding on algae within hours after coming off, while its wound healed in about a day. The body however didn’t survive very long before starting to decompose. The new bodies could be fully developed in less than a month.
After the initial discovery, Mitoh and her colleague Yoichi Yusa took a closer look at two types of slugs and noticed a groove on the neck of the slugs.
Their research found that out of 15 Elysia marginata slugs, five decapitated themselves. They began feeding on algae within a few hours and began to regenerate their heart within seven days. After 20 days, the slugs had regenerated their new body, CNN reported.
Out of 82 Elysia atroviridis slugs, three got rid of their old bodies, with two regenerating new bodies within a week.
In a separate group, 64 E. atroviridis slugs without parasites did not self-decapitate.
One of the slugs in the experiment was also able to complete the regeneration process twice.
Its not clear exactly why the slugs shed vital body parts, but some animals do it to remove parasites, which was one possible hypothesis to come out of the study.
We think that this is the most extreme case of autotomy, Yusa said in the study. Some animals can autotomise their legs or appendages or tails, but no other animal shed their whole body.
How the slugs manage to survive without a heart and other vital organs for up to nearly a month also remains a mystery. But the scientists think they use the energy from the photosynthesis occurring in cells that theyve gained from algae eaten.
A sea slug pictured before autotomy.
Ángel Valdés, professor and department chair of biological sciences at California State Polytechnic University, told CNN that the findings were intriguing.
Other sacoglossan sea slugs can regenerate appendages or other parts of the body, but this is an extreme case, Valdés said.
Professor Maria Byrne, from the University of Sydney, told The Guardian she called them solar-powered slugs.
Byrne, who is a marine biologist, told The Guardian that some starfish species are able to regrow a new central nervous system, or regenerate a new body from a severed arm.
She called the new research on the sea slugs being able to regrow a full body kind of remarkable.
It underscores the fact that still in the 21st century, we truly do not know what is possible in biology, Alejandro Sánchez Alvarado, a molecular biologist at the Stowers Institute for Medical Research, was reported saying in Science Mag.
In the study, Mitoh said that more needs to be learned about the phenomenon, both about the species in the experiment and other animals.
