A new study involving nudibranches has shed light into how they warn potential predators that they contain toxic defences.
Predator animals swiftly learn that brightly coloured animals are usually poisonous or are vile to the taste—essentially that they are not to be eaten.
Based on this assumption, researchers from the University of Queensland (UQ) Visual Ecology Lab thus theorised that there would be limited variation in the visual warning signals of prey animals, so potential predators would be immediately deterred upon seeing the prey animal’s appearance.
Their study, published in the Proceedings of the Royal Society B, provides more evidence of how variations in animal coloration can be maintained as it evolves at the same time.
Using the Gonibranchus splendidus in their study, they observed that the nudibranch displays a consistent yellow brim around a white body with red spots. It is found in the Southern Great Barrier Reef to New South Wales. The colour and pattern of the red spots vary significantly across populations, but the yellow rim is the common factor.
"Natural selection may act on parts of the colour pattern in very different ways, allowing for the yellow rim to be stable, but the red spots to be highly variable,” said Dr Karen Cheney, of the School of Biological Sciences.
"We showed that fish predators (triggerfish Rhinecanthus aculeatus) only pay attention to the yellow border of the colour pattern when learning avoidance of the signal and they pay little attention to the red spots," she added.