Disruptive coloration and behavior facilitate camouflage of blue-spotted cornetfish against complex coral reef bottoms

Abstract

Avoiding recognition involves the use of extraordinary strategies, among which camouflage is the most common. Crypsis, a usual form of camouflage, involves, among many other strategies, disruptive coloration that uses marks that disguise the contours of creatures to hide it. Fish that live on coral reefs have developed several cryptic strategies to avoid the risk of detection. The blue-spotted cornetfish, Fistularia commersonii, presents a pattern of dark bands that give the perception of disruptive coloration; however, this strategy has not been characterized for this fish. This study was conducted on the eastern coral reefs of Gorgona Island National Natural Park (Colombia). To confirm whether F. commersonii presents a disruptive pattern, photographs, and videos in situ of the individuals were taken, in addition to recording aspects of their behavior during changes in coloration. After strict selection, different images were processed and evaluated using three different visual systems (potential predator, potential prey, and human) to calculate the GabRat metric, that is detect consistent to inconsistent edges of a pattern. The images analysed and the observations indicate that this species displays a disruptive pattern that is used more frequently in the reef flat and during alert states, either in the presence of a possible predator or during the search for food.