No body, no bother, for regenerating sea slugs

SEA slugs are capable of regenerating their bodies after their heads become separated, a study has found.

While some animals are able to grow a tail or a limb, researchers have now discovered two species of sea slug that can grow a whole new body complete with heart and other internal organs.

The heads of relatively young slugs (226-336 days after hatching) moved immediately after separation from the heart and body and started to feed on algae within hours, according to the study published in Current Biology. They started regeneration of the heart within a week, and within about three weeks regeneration was complete.

They also discovered the heads of older individuals (480-520 days) did not feed and died in about 10 days. In either case, the cast-off bodies did not regenerate a new head, but the headless bodies did move and react to being touched for several days or even months.

Sayaka Mitoh, of Nara Women’s University in Japan, said: “We thought that it would die soon without a heart and other organs, but we were surprised to find that it regenerated the whole body.”