A new study has observed that a species of small fish uses homemade coral-scented cologne to hide their food from predators.
The study shows that animals don't need an exoskeleton to use chemical camouflage, meaning more animals than previously thought could be using this survival tactic.
The study found that Filefish evade predators by feeding on their home corals and emitting an odor that makes them invisible to the noses of predators and chemical camouflage from diet has been previously shown in insects, such as caterpillars, which mask themselves by building their exoskeletons with chemicals from their food.
Rohan Brooker, a post-doctoral fellow in the School of Biology at the Georgia Institute of Technology in Atlanta, said that this was the very first evidence of this kind of chemical crypsis from diet in a vertebrate and this research showed that one did not need an exoskeleton that for this kind of mechanism to work.
For the new study, researchers traveled to Australia's Lizard Island Research Station in the Great Barrier Reef, where they collected filefish and to show that filefish smelled like their home coral, the researchers recruited crabs to sniff them out. The filefish were fed two different species of coral i.e. each species of coral is home to a unique species of crab. The crabs were given a choice between a filefish that had been fed the crab's home coral and a filefish that had been fed a coral that is foreign to the crab. The crabs always sought the filefish that had been feeding on the crabs home coral. The filefish smelled so strongly of coral that sometimes the crabs were attracted to the fish instead of coral, when given a choice between the two.
The researchers tested cod to see how they responded to filefish that had been fed various diets. Cod, filefish and corals were put in a tank, with the filefish hidden from the cod. When the filefish diet didn't match the corals in the tank, the cod were restless, suggesting that they smelled food. When the filefish diet matched the corals in the tank, the cod stayed tucked away in their cave inside the tank.
The study is published in the journal Proceedings of the Royal Society B.
