Swimmers’ big feat: walking

The first animal to crawl onto land from the ocean probably resembled today’s salamander, and researchers have wondered how it switched from swimming to walking.

Now European scientists have built a robot with a simple electric nervous system that they say mimics that change.

The robot doesn’t look much like a salamander -- it’s nearly a yard long and made of nine bright yellow plastic segments each containing a battery and microcontroller -- but it does seem to move like one.

The point was to understand how a spinal cord that had developed to direct a swimming motion could handle the different coordination needed for walking, according to the team led by Auke Jan Ijspeert of the Swiss Federal Institute of Technology in Lausanne.

They first designed a basic nervous system modeled on that of the lamprey, a primitive, eel-like fish. That design was then modified to show how it could evolve to also control walking.

To prove their point, they built the salamander robot -- which walks across floors and down the beach, and even manages to swim in Lake Geneva.

To swim, it undulates like the lamprey, but on land the robot uses a slow gait with diagonally opposed limbs moving together while the body forms an S-shape.

The work, the researchers reported Friday in the journal Science, shows “how robots can be used to test biological models, and in return, how biology can help in designing robot locomotion controllers.”

The Swiss National Science Foundation and the French Ministry for Research and Technology funded the study.