A coral-reef fish can match its scent to the odour of the surrounding reef, masking itself from predators.

Credit: David Fleetham/OceanwideImages.com

Harlequin filefish (Oxymonacanthus longirostris; pictured) live around reefs in the Pacific and Indian oceans and feed on particular species of coral. A team led by Rohan Brooker at James Cook University in Queensland, Australia, tested whether aquarium-dwelling fish conceal themselves by emitting a scent that is similar to those generated by the corals that they consume. The authors found that when they exposed species of coral-inhabiting crabs to the odour of fish that ate that same coral species, the crabs preferred those fish to animals that ate another coral. This suggests that the filefish's diet influences its scent.

Moreover, a filefish predator, cod, had difficulty detecting the fish when they were near the coral on which they were fed. The study provides the first evidence for chemical-based camouflage in a vertebrate.

Proc. R. Soc. B http://dx.doi.org/10.1098/rspb.2014.1887 (2015)