Colourful stars at Basel Zoo
Time left between Christmas and New Year’s Eve? Why not visit the Zoo. In Basel Zoo’s vivarium the world is topsy-turvy: the little stars which usually shine in the sky can here be found on the aquarium floor. They are yellow, pink, bright orange or white and have no heart or brain, but are still capable of amazing things. Running, burrowing, climbing, clinging: starfish can do it all.
There are probably almost 2,000 species of starfish spread across all the planet’s oceans and seas, with around a dozen living in Basel Zoo. No-one knows exactly how many such creatures are living in the vivarium – there are hundreds distributed among the sea aquariums.
Most starfish have five arms or a multiple thereof, but animals with seven, eight, thirteen or more arms are not uncommon. However, starfish do not just have arms, they also have ‘feet’. These can be found beneath the arms and are used by the starfish to move around. This is done by stretching a group of the moving feet out in the right direction, clinging to the base beneath and then shortening them again. This shortening pulls the animal’s body along – not a fast process, but nimble and steady all the same.
All five arms of a starfish are equal and can move independently of each other. Nevertheless, the starfish can choose the direction of travel, as its nervous system – with five-fold symmetry – always concedes to the majority of the arms in true democratic fashion.