I think we can all agree that, in certain situations, it would be useful if you could pop your head off your shoulders and then just go about your business unbothered. Imagine, for example, walking into jury duty after exhausting your postponements, and oop! There goes your skull, ejected from your body as if by an invisible blade, and even though there’s no blood and both corporeal segments seem functional, you obviously can’t sit for a trial without your head. It’s simply not done; automatic dismissal. This is a convenient and airtight out for basically any unsavory scenario, which is why I envy Japanese sea slugs. According to a new study, published in Current Biology, two species of these slimes can self-decapitate at will, then get back to algae snacking within days. I mean, what the hell kind of sorcery is that?
Quite possibly, slug-specific sorcery. Lead study author Sayaka Mitoh of Nara Women’s University in Japan told the New York Times that, a few years ago, she was casually observing the lab slugs when she noticed the severed head of an Elysia marginata roaming freely around its tank, which is unusual behavior for any kind of head. The neck tissue reportedly looked “dissolved,” like the slug had “ripped its own head off,” per the Times. Mitoh said the sight left her “surprised and shocked”: Not only had the slug head survived separation from its vital organs, it also regenerated a new body.
After seeing a few more slugs do the same, Mitoh and aquatic ecology professor Yoichi Yusa decided to do the decapitating themselves. They sliced the heads off of 16 sea slugs: Six of them started regenerating, three to completion. One even managed to shed and regrow a body on two separate occasions. Typically, the head wounds healed within a day and from there, the regrowth process generally wrapped within three weeks. The speed itself is impressive, but as Yusa pointed out to the Associated Press, sea slugs — or, at least, Elysia marginata and Elysia atroviridis — also appear to be the only animals that can “shed their whole body.”
Researchers posited that, rather than fleeing predators as is usually the case when a creature throws off a tail or something, slugs may jettison their heads to avoid invasive parasites. But the practicality is not the only reason this singular trick is enviable — for slugs, and in an ideal world, for humans. Would it be rad at parties? 100 percent. Spooky for Halloween? To an arguably traumatizing degree, yes. Delightful to your friends and terrifying to your enemies? Absolutely, on both counts. Convenient for dodging yet another interminable Zoom? Hm, well. You may still need your papier-mâché head for that.