Animals come up with all sorts of displays in an attempt to attract a mate. However, in some species, the line is sometimes very blurred between what is considered sexy or just scary. The toad-headed agama, a Demogorgon-like lizard with its mouth open, is one such species. A study finally closes the debate.
Conspicuously colored signals can evolve through sexual selection to become ornaments or armaments, thus conferring a physical advantage on their bearer as part of the courtship displays. Conversely, visible colors can also evolve as warning signs to deter predator attacks. Visible patches of color can also evolve for one purpose (quality indicators), to then be co-opted for another (means of defence).
That being said, back to our toad-headed agama (Phrynocephalus mystaceus). If you are not familiar with this animal, it is a species of saurians from the Agamidae family. These lizards are capable of rolling out their brightly colored cheeks in both sexes. When folded against the head, these flaps appear very discreet. When deployed, they eventually become highly visible and increase the appearance of the body size of these animals.
As part of new work published in the journal Biological Journal of the Linnean Society, researchers wanted to understand the usefulness of this ornament. Does it play a role in social signaling for courtship or is it a warning signal? To find out, the researchers captured several specimens in China to observe their interactions in the arenas.
So why are these lizards playing Demogorgons?
During their experiments, the team recorded the interactions of several male-male and female-female pairs. Their observations revealed no cheek deployments indicating the technique could be used against competing partners. The interactions between males and females also demonstrated that the technique had visibly no no place in courtship either. Many tails wagged, but no faces flared.
However, when they were shown pictures of predators, things started to change. The presence of a falcon in the air, a known predator of these animals, makes 3% of subjects react. This percentage is increased to 12% with images of real lizards in the wild.
Somewhat surprisingly, a “flossing attack” ultimately turned out to be the biggest instigator. The lizards have indeed opened their mouths wide in 84% of cases. Researchers suspect it was a demonstration of surprise.
The Demogorgons of the series Stranger Things certainly come to mind when imagining an agama spreading its face in front of an enemy, but is this technique effective in the wild? Future work may one day give us the answer.