On a windy day, Dutch day-trippers may be lucky enough to spot a member of the elusive Strandbeest family crawling along one of Holland's beaches. With a massive two-tonne body, the largest creature in the family, Ventosa Siamesis - see video above - stands nearly 5 metres tall, and with its articulated body a gigantic 10 metres long it is certainly a creature to behold.

These beasts are constructed not from flesh and bone but by hand from plastic bottles and recycled tubing. They use wind to power their locomotion, and can trap air in a "stomach" made of plastic bottles, so they retain a power source for movement in case the wind stops blowing. Their creator, physicist-turned-kinetic artist Theo Jansen, argues they also have some brain-like function as they respond to the changing environment: on very windy days, the Strandbeest (which translates as "beach beast") can dig its heals into the sand to stay put, for example. They can even be said to evolve like living species, as their designs are based on genetic algorithms and only the most successful family members will have their genetic code used in future generations.