THE relaxing touch of a cleaner fish can pacify even the most vicious predator, turning coral-reef 鈥渃leaning stations鈥� into safe havens for all.
Cleaner fish live up to their name: they eat parasites they find on other fish. What鈥檚 more, they use their fins to throw in a gentle massage to make their 鈥渃lients鈥� more cooperative, which is especially helpful if the customer is a predator that could attack the cleaner.
To test how this affects the attitudes of predators towards other tasty fish in the neighbourhood, Redouan Bshary at the University of Neuch芒tel in Switzerland and his colleagues built miniature coral reefs in aquaria and observed the interactions between cleaners, their clients and prey species that were not clients of the cleaners.
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They found that predators chased prey only one-third as often in aquaria where cleaners were present compared with those in which they were not. This was not because the predators were busy being groomed and so had less time for hunting, as their aggression remained in check even at times when they were not being cleaned. What鈥檚 more, the longer a cleaner stroked a predator, the further the number of chases decreased (Behavioral Ecology, ).
鈥淲e next want to measure the predators鈥� heart rate with hydrophones to see if touch really relaxes them,鈥� Bshary says.
