Sometimes science is stranger than science-fiction.

In 2018, Sayaka Mito of Nara Women’s University was studying Elysia marginata, a type of sea slug found off the coast of Kagoshima Prefecture and bred in the school’s lab. Normally, sea slug research is rather mundane business, but one morning when entering the lab she found something truly shocking.

In the tank, one of her slugs appeared to have been murdered, with it’s head lying detached from its body. However, after a moment she found that the head was still moving around the enclosure. It was then she realized that the “murderer” was none other than the slug itself!

We’ve all heard of some animals’ ability to cuts off one of its own limbs or tails in order to escape predators. It’s a process called “autotomy,” not to be confused with “autonomy” which is an individual’s free will. Planarian flatworms are said to be the kings of autotomy. Cutting one in half will result in two living planaria, but unfortunately for them, this means people are constantly cutting them up.

Sea slugs are more complex creatures than flatworms and have organs such as hearts, making the odds of surviving decapitation a lot slimmer. Nevertheless, after only a few hours, Mito, whose research was published this week, was able to feed her slug head some seaweed. About a week after that, traces of a new body and working heart began to develop. By the third week, the slug’s body was nearly complete again.

This prompted further study, during which Mito found that another close relative, Elysia astroviridis collected from Mukaishima in Hiroshima Prefecture, had the same ability. However, there were limitations. The remaining bodies did not grow a new head, but some continued to twitch in response to stimulus for a long time before beginning to decompose. In addition, some slugs were unable to detach their bodies and older ones could perform the autotomy but died from starvation before being able to regenerate.

▼ A decapitated sea slug out for a stroll, notice how the body twitches when the head bumps into it

Eating without a digestive system is indeed a challenge, but heartier sea slugs are able to pull it off by consuming algae. Their bodies – or what’s left of them – are able to adopt the chloroplasts in the algae and perform photosynthesis which nourishes the slug with the resulting chemical energy.

It’s still a bit of a mystery why the slugs decapitate themselves, but Mito suspects it isn’t to evade predators. The leading theory is that its purpose is to rid them of parasites.

Naturally, all this talk of parasites and life after decapitation got netizens thinking that the world of manga has finally come to life.

“If manga has taught me one thing, it’s that you have to kill them by piercing their heart first.”
“They should be called Eren Yeager slugs.”
“Awesome, now that’s self-improvement!”
“The head’s all you need anyway.”
“We must merge with the slugs to form the perfect human.”
“They don’t need a heart? What did their heart do in the first place?”
“They can survive as long as their head is intact, just like Piccolo!”
“Deadpool slugs.”
“I would like this power soon too please.”

Scientists are hoping this discovery could provide further insights to regeneration processes that could be applied to medical science, but we’re still probably a long way off from being able to rip off our own heads and growing new bodies, as great a TikTok post as that would be.

It sure would be nice though. With swimsuit season just around the corner, it’s looking like I might be better off just jettisoning my own parasite-ridden tub of lard and starting from scratch.

Source:, My Game News Flash
Top image: ©SoraNews24
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