We all know that lizards lose their tail to defend themselves against a predator, but this is just a tail. Japanese researchers have discovered one of the most extreme limb regenerative cases ever found – sea slugs that can sever their own heads and regrow an entire body from it.
In a study published on March 8 in Current Biology, researchers from Japan’s Nara Women’s University found two species of sacoglossan sea slug that can voluntarily drop their heads and then regenerate their entire body from it – complete with vital organs and a new heart.
The incredible finding caught the team by surprise. They were initially raising the slugs in the laboratory to analyze their biology when a disembodied head began crawling independently. It seemed to be the outcome of autotomy or self-amputation (the process of releasing a body part on command), although typically, the discarded part weakens and eventually dies.
Sayaka Mitoh, the study’s lead author, explained:
We were surprised to see the head moving just after autotomy. We thought that it would die soon without a heart and other important organs, but we were surprised again to find that it regenerated the whole body.
The team steered their attention to studying this fascinating ability. They found that both the body and head moved independently after being separated from each other. After a few days, the wound at the back of the head (where the body was removed) closed up as the head continued to feed on algae. Within only a week, the head regenerated a new heart, and it took around three weeks to grow their entire new body.
While the headless bodies didn’t regrow a new head, they still moved around and responded to touch for a few months. However, age appeared to affect the process – younger slugs could easily lose their heads and regrow, but when older ones tried, they didn’t feed and died roughly 10 days later. The scientists don’t know why or how this happens and what triggers the process, but more research may unleash these odd creatures’ secrets.
The planet is filled with incredible species, including some that thrive without breathing, seeing, or hearing and others that thrive in toxic environments that would otherwise kill any organism instantly. There are also half male/half female animals, two-headed animals, and beetles so tough they could survive getting run over by a car.
