Cleaner fish wear "uniforms" to advertise, avoid danger

From an article by Christine Dell'Amore on National Georgrpahic News:

Like police and nurses, cleaner fish on coral reefs wear uniforms to signal their "professions"—a tactic that also helps the fish avoid being eaten by their clients, a new study says.

Several species of small reef fish are known to invite larger fish to stop by "cleaning stations," where the cleaners groom their customers and pick them free of parasites.

The clients swim away spic-and-span, and the cleaners get an easy meal: "a classic example" of a mutually beneficial relationship, the researchers write.

However, scientists have long wondered how bigger, fish-eating clients find cleaners and apparently recognize that the smaller fish are off the menu.

Karen Cheney and colleagues decided to test the theory that the cleaners' colors and body patterns are what set the fish apart.

Her team found that cleaner fish—such as gobies and wrasses—are more likely to sport a dark side stripe accentuated by patches of blue and yellow.

"We believe that they do exhibit a 'cleaner uniform' in order to make them conspicuous and easy to distinguish on a coral reef," Cheney, a biologist at the University of Queensland in Australia, said by email.