We have completed maintenance on DiscoverMagazine.com and action may be required on your account. Learn More

Fish Perfume Themselves With Coral as Smell-Camouflage

By Bethany Hubbard
Dec 10, 2014 10:18 PMNov 20, 2019 5:16 AM


Sign up for our email newsletter for the latest science news

Evolution has produced some masterful solutions for animals to avoid predation. Look no further than the camouflage abilities of the dead leaf butterfly, the flower mantis, or the freaky vanishing octopus for proof. But, a new study takes trickery to a whole new level. Researchers have discovered that the tropical harlequin filefish camouflages its scent by eating the coral it lives on, so as to blend into the olfactory background. It’s the first time a vertebrate animal has been found to practice such smell-deception. Olfactory Chameleons It may come as a surprise that many undersea critters possess a keen sense of smell  it’s the sense that helps salmon return to their home rivers to spawn, for instance. Researchers therefore wondered if some fish used smell-camouflage to hide from predators. They chose to study the harlequin filefish, a tropical fish that lives near coral reefs. The filefish also feeds on the very coral it calls home. And, this coral, Acropora spathulata, is not particularly nutritious  at least not the best option around. So, scientists wondered, could there be another driving factor? The Hunger Games To answer this question, researchers placed sixteen filefish into four tanks. Two tanks were exclusively fed the Acropora coral, while the other two received a different species, Pocillopora damicornis, to feast on. Researchers first tested the fish’s chemical camouflage by bringing in some expert tasters  species of crabs that feed on one of the two types of coral. If anyone should know the smell of coral, scientists reasoned, it was these crabs. Researchers placed sections of pipe in the tank: one contained a filefish and the other a piece of coral. The crabs couldn’t see what was inside the pipes, forcing them to rely on smell alone. In both cases, researchers found, crabs would prefer the filefish fed on tasty coral over a piece of unappetizing coral  indicating that the fish smelled like their food. Also, though most crabs preferred tasty coral over a filefish fed on tasty coral, a high percentage still opted for the fish itself. In a second experiment, researchers employed a real-life predator of the filefish: cod. When filefish smelled the same as the coral in their tanks, cod were uninterested in them, but when they stuck out scent-wise then cod were quite interested indeed. The results were published in the journal

Proceedings of the Royal Society B

this week. Masters of Disguise The filefish, then, are able to thwart predators through a chemical cloak of invisibility, just based on what they eat. The researchers say this is the first evidence that chemical crypsis caused by diet can be seen in vertebrates  proving that vision isn’t the only sense to be fooled. And that the animal world is even craftier than we’d originally thought.

1 free article left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

1 free articleSubscribe
Discover Magazine Logo
Want more?

Keep reading for as low as $1.99!


Already a subscriber?

Register or Log In

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Our List

Sign up for our weekly science updates.

To The Magazine

Save up to 40% off the cover price when you subscribe to Discover magazine.

Copyright © 2024 Kalmbach Media Co.