Researchers in Japan have discovered that two species of sea slugs can decapitate themselves and grow new bodies. The findings were published this week in the journal Current Biology.
“These slugs have like a little groove that separates their head from their foot, and it's like a weak point in the body,” says Patrick Krug, marine biologist at Cal State LA. “And it seems like they can, through muscular contraction, just literally pull their head off of their own bodies. And the head just crawls away and jettisons the body.”
Why do the slugs do this? Parasite infections.
“There are … crustaceans, like tiny little shrimp, that burrow into the slug’s body and permanently infect it. And there’s really no way for the slugs to get rid of them other than jettisoning the body. And so the hypothesis of these researchers is that this is an adaptation to get rid of a parasite-riddled body and start over again.”
And to regrow their bodies, these slugs take one to three weeks, says Krug.
A sea slug from Hawaii. Photo courtesy of Patrick Krug.
Other organisms that can do something similar, such as starfish that can regrow a whole body from one arm, and flatworms that can regrow a head or back half of their body. Krug says those animals, however, have very simple bodies, with a diffuse network of nerves, no brain, and no whole organ systems.
In contrast, these slugs have a heart, kidneys, digestive system and reproductive organs. “It's pretty amazing that a head by itself could regrow that whole body with all those organ systems.”
He continues, “So it's kind of exciting to think about what that might mean for regenerative medicine and for applications in biotechnology. Because I just don't think people thought that an animal at that level of complexity was even capable of something like this. So it opens the door to what we might be able to engineer.”