A new material inspired by sea cucumbers can change easily from hard and rigid to soft and floppy, US researchers say.

When wet, the material changes from a stiff plastic to a rubber-like state in seconds, and it can change back just as quickly, the researchers report today in the journal Science.

It's a feature they say may make it suited for medical implants.

The material mimics a trick that sea cucumbers perform. The invertebrate sea creatures can quickly change the stiffness of their skin, forming a kind of armour in response to a threat.

"We used the skin of these sea cucumbers as the basis of a new class of artificial material that can change their mechanical properties on command," says Professor Chris Weder, a researcher at Case Western Reserve University.

Weder and colleagues plan to use the material in medical applications, such as pliable brain electrodes used in treatments for people with Parkinson's disease, stroke or spinal cord injuries.