This Bizarre Slug Can Chop Off Its Head and Grow a New Body

by Katie Maloney
(Photo by Michel JOZON/Gamma-Rapho via Getty Images)

Everyone needs to stop what they’re doing and read about these self-dismembering seas slugs.

A group of doctorate students at the Yoichi Yusa laboratory at Nara Women’s University in Japan made a pretty cool discovery this week. The team observed nine sea slugs that spontaneously discarded their bodies and began to regenerate.

You may be thinking, “Wow, big deal. There are a ton of species with the ability to regenerate body parts.” And you’re totally right. However, all of those species cut off and regenerate non-essential body parts like limbs or tails. Until now, no one has discovered a creature that cuts off its entire body and just starts over. These slugs are surviving without vital organs like the heart, intestines, and reproductive systems.

Ph.D. student Sayaka Mitoh examines the life cycle of sea slugs at the school. During an interview, she said that this is the first time she’s ever seen a sea slug do this.

“We were really surprised to see the head moving just after autotomy,” she said. “We thought that it would die soon without a heart and other important organs, but we were surprised again to find that it started to regenerate the body.”

Her team added that “this is the first example of such extreme autotomy as far as we know. Some other animals such as planarians, starfish, and polychaetes have greater abilities of regeneration, but most of them do not have a heart.”

So How Does This Whole Self-Decapitating Sea Slug Thing Work?

According to the observers, sea slugs that were less than one-year-old discarded their heads. Within hours of decapitating themselves, they began eating algae again. Days later, the wound where the head was severed had healed. And in just one to three weeks the seas slugs formed new bodies complete with vital organs.

Can we just acknowledge how funny it is that the first thing the sea slugs do is eat? Like, before they even grow new bodies they need to stop for a lunch break. But, it makes sense. It has to take a lot of energy to severe your own head.

And if that whole thing isn’t bizarre enough, we also have news about the discarded sea slug bodies. Although they never grew back heads, they did respond to tactile prompts, sometimes even months after decapitation.

In conclusion, these sea slugs are living with heads, without heads, and with brand new heads. There’s basically nothing that these slugs can’t do.