The Smell of Success

“You are what you eat” is a familiar adage and one that’s worth bearing in mind during the period of festive feasting. However, some creatures have taken the adage altogether more literally and have turned it to their advantage.

The Orange-Spotted Filefish (Oxymonacanthus longirostris) is a bright and beautiful marine species that makes its home among the reefs of the Indo-Pacific Ocean, feeding almost exclusively on polyps of Acropora coral and relying on it for shelter. This diet is undoubtedly specialiSed and at first glance may seem like an unnecessarily burdensome restriction, but there’s a hidden benefit to it that helps ensure the little fish’s very survival.

The Filefish is already perfectly visually camouflaged to suit its environment, often "locking on" to coral and pretending to be a coral branch itself. But by steadily munching on Acropora, it is also able to alter its own body chemistry in order to smell just like the coral it feeds on. This essentially makes it “chemically camouflaged” to predators, adding to the already effective visual camouflage.

It’s the first time that scientists have ever observed a species using diet to deliberately alter its smell in this way, and while it’s certainly a neat trick for the Filefish, it should perhaps give Christmas revellers some pause for thought before reaching for that second helping of Brussels sprouts…