For thirty years, inventor Theo Jansen has created strandbeests (Dutch for “beach animals”). They are mostly PVC tubes.
As they step and slither on the flat beaches of the Netherlands, they avoid inland dunes and shy away from the sea. They have water feelers, tubes suspended inches above the flat sand, that suck in air. Once the strandbeest sucks in water, it can feel the difference — water has more resistance than air — causing it to backtrack to the sand.
They keep moving, temporarily, after the wind dies down. Wind pushes their sails, which move parts that pump air into soda bottles. This is saved for when the wind stops.
The movement starts with a loosely-jointed square, as shown in the following 50-second video. The caterpillar is different, a later invention.
Jansen’s formal education was in applied physics, and he has been an artist and writer. He visited Pasadena when NASA’s Jet Propulsion Laboratory (JPL) invited his advice on designing a Venus rover. Venus has a steady wind. It is so hot there that computers won’t work, so the JPL engineers are interested in Jansen’s creations and their sensors which are mechanical, not electronic. More here.
These seem more than mere machines. I see art, grace, and a pioneer’s vision. Jansen uses words like “evolution” and “genealogy” when writing about his strandbeests. He calls them “new forms of life.” He dreams of wild herds that will outlive him. Strandbeest.com