Orange spotted filefish takes on the smell of its food

QUEENSLAND, Australia, Dec. 10 (UPI) -- For the orange spotted filefish (or harlequin filefish), the saying "you are what you eat" isn't just a cliche, it's a way of life. At some point in evolutionary history, the harlequin filefish began taking on the appearance of its preferred coral. That's all and well for escaping predators that rely on their eyesight. But what about bigger fish with a keen sense of smell?

In a new study, researchers say the orange spotted filefish (Oxymonacanthus longirostris) is able to take on the smell of its food in order to camouflage its scent as it hides among the same coral it dines on. The fish ingests chemicals from the coral that allow it to shroud itself in the coelenterate's musk.

"Most of the literature on camouflage focuses on visual methods, but many animals use smell more. For these animals, chemical camouflage may be far more important to stay hidden," the study's author Rohan Brooker, now a postdoctoral student at the Georgia Institute of Technology, told National Geographic.

Brooker's work was detailed this week in the latest issue of the journal Proceedings of the Royal Society B. Brooker conducted the research while studying at James Cook University in Australia.

In one of several experiments showing the filefish took on the smell of their preferred coral, researchers placed cod in aquarium tanks with two separate groups of the harlequins. One group was fed Acropora coral, their favorite. Another was fed a coral not normally part of the filefish's diet. The cod were less active and less predatory when in the presence of Acropora-eating fish -- suggesting their disguise works.

"I suspect that this method of hiding is probably a lot more common than any of us guessed," Brooker said.