Reef Fish Can Hide By Changing The Way They Smell

Harlequin filefish

Harlequin filefish, a type of reef fish, don’t just camouflage themselves by looking like coral. They also do it by smelling like coral.

An Australian-led study has found the fish achieve their odour by eating the coral and that their smell is so similar to the coral that they can actual confuse small crabs.

“For many animals vision is less important than their sense of smell,” study lead author Dr Rohan Brooker from the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Queensland said.

“Because predators often rely on odours to find their prey, even visually camouflaged animals may stick out like a sore thumb if they smell strongly of ‘food’.”

The research, published in the journal Proceedings of the Royal Society B, found the harlequin filefish changed its smell to match the coral it ate.

“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,” Dr Brooker says.

However, the filefishes’ cover is blown if it shelters in a different type of coral than the one it has been eating. The predators can distinguish its presence and track it down.

The ability to chemically blend in occurs in some plant-eating invertebrates but this is the first time this type of camouflage has been found in higher order animals such as fish.

“This is very exciting because it opens the possibility of a wide range of different animals also using similar mechanisms, right under our noses,” Dr Brooker said.

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