Jellyfish can learn from their mistakes - even though they don’t have a brain

Scientists from the universities of Kiel and Copenhagen placed Caribbean box jellyfish in a special tank surrounded with stripes that resembled mangrove roots. White stripes looked like roots that were close up and grey stripes like roots that were further away. At first, deceived by the grey stripes, the jellyfish frequently bumped into the side of the tank. But after 7.5 minutes, they were swimming 50% further from the side of the tank and had halved the number of collisions with the glass. This is known as ‘associative learning’. Which is when animals form mental links between stimuli and behaviours. Only complex animals were thought to be capable of it but jellyfish adapted just as quickly, despite having only 1,000 nerve cells and no centralized brain.