UK scientists have discovered that some fish learn by watching the experiences of others.
Durham University scientist Jeremy Kendal, writing in the journal Behavioural Ecology, caught 270 sticklebacks from a local river. The fish were divided into groups. The first group were placed in a tank with two feeders, one which dished out generous portions of blood worms and another which was more frugal.
A test revealed that the fish had learned the drill and at this point they were then confined within a 'viewing gallery' section of the tank whilst a second group of fish were introduced.
But this time the scientists reversed the feeders so that the previously generous one was now more stingey and vice versa. The confined 'educated' sticklebacks were then left to watch how the newly-introduced fish fared. Afterwards they were released again and the team observed which of the two feeders they now favoured.
Incredibly, just by watching how the other fish had got on, over 75% of the observering fish had learned from the experiences of the other sticklebacks that the feeder situation had reversed. Even more impressive was that, in a subsequent experiment, when the team adjusted the relative generosity of the feeders the observing fish only changed their behaviour if they saw the other fish doing better in the new situation than they had in the old.
This kind of learning approach, known as a 'hill climbing strategy' is probably key to helping these animals to escape from predators.
"These fish are too vulnerable to forage alone," explains Kendal, "so they have to move around in groups. They are therefore social, and by watching the outcomes of others and responding appropriately this is a sound strategy to avoid predation and maximise returns."
And regardless of the evolutionary benefits, any claims of fish having a once-round-the-tank-memory is definitely a fish out of water, at least in the stickleback world.