Filefish Species Uses Chemical Camouflage To Alter Its Smell

December 13, 2014

Chuck Bednar for redOrbit.com – Your Universe Online

Scientists have for the first time discovered a creature that chemically disguises itself by ingesting chemicals from its prey in order to hide from potential predators, according to new research published this week in the journal Proceedings of the Royal Society B.

The creature in question is the coral-eating harlequin filefish, and lead author Dr. Rohan Brooker of the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University and his colleagues have found that the creature changes its odor in order to match the coral that it consumes.

“For many animals vision is less important than their sense of smell. Because predators often rely on odors to find their prey, even visually camouflaged animals may stick out like a sore thumb if they smell strongly of ‘food’.” Dr. Brooker said in a statement. “By feeding on corals, the harlequin filefish ends up smelling enough like its food that predators have a hard time distinguishing it from the surrounding coral habitat.”

The harlequin filefish, which is also known as the orange spotted filefish, actually matches the smell of the coral’s musk so closely that small crabs (which live on coral branches) were unable to distinguish it from actual coral, the researchers said. They called it a remarkable example of how closely living things can adapt to their habitats.

According to UPI reporter Brooks Hays, Dr. Brooker and his colleagues conducted several experiments, including one that demonstrated that the filefish was able to take on the smell of its preferred type of coral. In one experiment, the study authors, placed cod in aquarium tanks with two separate groups of the fish.

One of the two groups was fed Acropora coral, their favorite type, while the second was offered a coral that is not normally a part of the filefish’s diet, Hays said. They found that the cod were generally less active and less predatory when in the presence of Acropora-eating fish, which suggests that their disguise was extremely effective.

“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,” Dr. Brooker told Carrie Arnold of National Geographic. “I suspect that this method of hiding is probably a lot more common than any of us guessed.”

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