SCIENCE LAB SCAMPER

IF THE BODY OFFEND THEE Decapitation as a way to improved health.

A few years ago Sayaka Mitoh, a Ph,D, candidate at Nara Women's University in Japan, was perusing her lab's vast collection of sea slugs when she stumbled upon a gruesome sight.

One of the lab's captive raised sea slugs, an Elysia marginata, had somehow been decapitated.

Ms. Mitoh then noticed the severed head of the creature was moving around the tank, munching algae as if there were nothing unusual about being a bodiless slug. Ms. Mitoh also saw signs that the sea slug's wound was self-inflicted.

It was as if the sea slug had dissolved the tissue around its neck and ripped its ows own head off.

Ms. Mitoh and her colleagues conducted experiments aimed at figuring out how and why some sea slugs guillotine themselves, Many animals will jettison body parts like tailes, which helps foil predators. But none had been seen to jettison their entire bodies.

Researchers suspect that Elysia marginata and another closely related species do that when they become infected with internal parasites.

Not all the sea slugs they monitored decapitated themselves, but many did. Bodies regenerated from the heads of both species, but the headless bodies stayed headless, although the discarded bodies reacted to stimuli for as long as months, before decomposing.

The head woulds the sea slug created during the operation took only one day to heal. Organs such as the heart took an average of one week to regenerate.

For most of the sea slugs, the regeneration process took less than three weeks to complete [Annie Roth]