There are two species of sea slugs that can not only decapitate themselves and survive – they can regrow their bodies.

There’s a few of us out there who wouldn’t mind growing a new head when we get bored of the old one, but that’s not quite the theory behind these marvellous slugs’ abilities.

Researchers theorised it could be a mechanism to rid themselves of parasites.

They studied a bunch of sacoglossan slugs from birth in a lab, and five began the self-decapitation after about 200 days.

They’d drop off their heads (a process called automising) and start eating a few hours later.

Within a week, their entire body started to regenerate.

Twenty days later, they were a whole new slug.

(One slug even did it twice.)

However of the 15 lab-studied slugs, the 10 that chose to decapitate later in life (at 480-plus days old), they also didn’t eat shortly after losing their heads, and subsequently died.

What does this tell us?

Well, researchers aren’t exactly sure – maybe it’s just a last-ditch chance at survival, they guessed.

“We want to study whether other species of sacoglossans have this ability to study the evolutionary pattern and process of such extreme autotomy and regeneration,” study author Sayaka Mitoh said, from Japan’s Nara Women’s University.