In order to attract a partner, animals may contort their bodies into all sorts of strange shapes (have you ever seen Brits dance abroad?), and in certain species, there is a small line between what is deemed seductive and what is simply scary. One of these species is the toad-headed agama (Phrynocephalus mystaceus), a lizard that rivals the Demogorgons from Stranger Things. Agamas may unfold their brightly colored cheeks in a spiky display that resembles a flower with fangs, and similar bursts of colors are sometimes associated with courting displays (have you seen Carnotaurus’ small, whirling blue arms?).
New study published in the Biological Journal of the Linnean Society suggests that these ferocious face flaps are actually a warning to predators. “Suspiciously colored signals may develop to resemble ornaments or weaponry as a result of sexual selection, hence imparting a fitness benefit to their bearer,” the scientists wrote poetically in their study.
“On the other hand, bright colors may have evolved through natural selection as [warning] signs or [startle] displays to prevent predator assaults. While noticeable color patches may have evolved for one reason (for example, quality indications), they may subsequently be co-opted for another (for example, anti-predator defense).” Researchers captured some agamas in China’s Tukai to watch their interactions in arenas in order to better understand what led them to flare their cheek flaps. They found 14 male-male pairings and 17 female-female pairs, but no cheek movement, indicating that they aren’t used to fight rival mates.
Trials between males and females also seemed to show that these cheek flaps had no role in the species’ courting, as no one flared their face despite a lot of tail movement. When predator pictures were displayed, though, things began to shift. The animals were first shown a picture of a flying falcon, which mostly drove them to flee, while 3% of them put their cheeks out. When the hawk photos were replaced with genuine free-roaming lizards, the proportion increased to 12.
The largest cheek instigator turned out to be dental floss, as lassoing lizards in an ambush prompted 84 percent of those seen to respond with what the researchers believe is a startle response. Because the flaps are tucked away when the lizard is at rest, if an agama finds itself in the hands of a predator, it may be able to frighten them away by abruptly changing its appearance. When thinking about an agama unfurling its face in front of a rival, a spectacular combat scene from the newest season of Stranger Things comes to mind, but how effective is it in real life? According to the experts, there is still more work to be done.
“Right now, further empirical investigations are needed to verify the predictions of deimatic display theory and to see how context influences an animal’s decision to use a deimatic display,” they said. “We centered our anti-predator reactions trials and measurements on the perspective of potential prey.” The next step is to see how a prospective predator reacts to the show to see whether it does actually shock them by overwhelming their sensory system.”