Twelve Periods of the Strandbeest

What it is#

Strandbeest (Dutch for “beach beast”) is Theo Jansen’s series of skeletons made from yellow plastic electrical tubing that walk on wind. His website says they have evolved since 1990 and are divided into 12 periods of evolution, each defined by the properties of its animals. He writes that by developing this evolution he hopes to understand existing nature better by meeting the problems the real Creator met.

The twelve periods#

Paraphrased from the period pages on his site.

Turning points worth a closer look#

The “sacred numbers” were computed. In the Chorda he developed a new walking system; the ratios between the rod lengths (his “sacred numbers”) were calculated with a genetic algorithm on his Atari computer. The leg is built of triangles, the basis of half-timbered structures: lots of air and little material, strong in support, light to lift and swing forward. He also writes that in self-chosen isolation he wanted to reinvent everything. His fitness function and algorithm details are not on that page.

Calidum: a material flaw takes a year to show. The heat gun has a high and a low setting; he used high at first because it was fast. Joints made that way turned brittle after a year. Currens Ventosa could no longer stand. The names Calidum and Tepideem come from the gun’s temperature setting.

Vaporum: a clear distinction. Before, the wind did the moving; now the animal moves itself. His account of the “stomach” is concrete: recycled plastic bottles hold air pumped to high pressure by the wind, using bicycle-style pumps made of tubing and driven by wings flapping at the front. A few hours fills the bottles. The “muscle” is one tube sliding in another with a rubber-ring piston; air in, it lengthens. In his words, the muscle is itself the bone, so it is light.

Cerebrum: avoiding the sea with no eyes or ears. Two sensors: a water feeler, a hose trailing on the ground that normally sucks air and whose resistance rises when it takes in water, which flips a “nerve cell” and makes the animal turn around; and a soft-sand feeler, which senses pressure building in the muscles when walking gets laborious. On top comes a “witching rod”: an analogue pedometer, a small pump on one leg adding air to a vessel with each step, so that pressure tracks step count; the animal turns when it has dropped almost to zero, and touching water resets the count.

Suicideem: a candid page. Umerus pushed a crankshaft with pumps between its shoulders, using less air and walking more regularly than the earlier Percipiere family. On the beach, uneven terrain and loose sand threw off the crank timing, the powerful pumps broke its own backbone, and in the end it walked 26 seconds on the sand. It preferred museum floors. The 72-legged Siamesis repeated the story, and he converted it on the beach back to the old Percipiere system.

Aurum: what to do in weak wind. At wind force five no sails are needed; gentle wind needs many large sails. He writes that the minimum wind to start the animals turned out to be 15 km/h. That is his own statement on his website, not a measurement, and it comes without the animals’ size, so it can only be read as an order of magnitude.

Volantum: taking off to escape sand. Sand attracts strandbeests and buries them. Ader could fly up to six metres, letting sand blow underneath, but was still anchored to a post. Multi Tripodes (2020, 36 legs) was too heavy to fly; with 24 legs it should.

Pregluton: period zero (1986–1989). When I wrote this the page on his site was still empty, so that row could only cite Wikipedia. By the 2026-10-22 re-check it had text: he calls it the period before the Gluton (1986–1989), says there were no animals of plastic tubing yet, that “life consisted exclusively of dreaming about life”, and that he made virtual animals on the computer subject to an artificial evolution. The site lists the 1989 Vermiculus Antramentum as the first life form: a rod moving on a computer screen. Wikipedia counts it as period zero, and now he confirms that himself.

Not verified#

• 28 legs for Animaris Vulgaris appears in press coverage; the Gluton page gives no leg count.
• “Inspired by Dawkins” is Wikipedia’s wording; his pages do not say it.

Series#

Part 1 of 3. Next: the geometry of the leg, then re-evolving it. Code and notes: meiluosi/strandbeest-evolution.