Animals are often named for their defensive tactics and adaptations. Just as frilled dragons (Chlamydosaurus kinghii) use their frills to dissuade predators, poison dart frogs (Dendrobates sp.) are covered in toxic secretions and snapping turtles (Chelydra serpentina) are quick to bite, inland bearded dragons (Pogona vitticeps) use their well-adapted beards to scare predators. Even in captivity, where they're noted for their docile nature, a startled bearded dragon may flare its beard at its keeper.
Habitat and Predators
Inland bearded dragons are native to the arid interior of Australia, though closely related species are found throughout the continent. A number of predators are found throughout this range, but the most important predators of bearded dragons are goannas, snakes, hawks and dingoes. Additionally, bearded dragons are sometimes cannibalistic in captivity, and their wild counterparts may consume other bearded dragons from time to time.
The first line of defense for bearded dragons is to remain undetected by predators. Bearded dragons are colored much like their surrounding habitat, and their bump- and spike-covered body further breaks up their silhouette. Bearded dragons remain motionless for long periods of time, so movement doesn’t often give them away, either. Unfortunately for the lizards, camouflage isn’t always effective against birds, or predators like dingoes and goannas, that hunt by smell.
Bearded dragons have an extendable pouch under the bottom jaw. When alarmed, the bearded lizards can inflate the beard greatly, making their head appear much larger than normal. Often, males have darker beards than females, though the beard color can change with the lizards’ mood and behavior; during copulation or predatory encounters, a beard often turns black. Bearded dragons also use their beards to intimidate conspecifics during territorial encounters.
Gaping and Biting
Bearded dragons usually open their mouths when displaying their beards, a behavior termed gaping. This is used as a threat, but if a predator or rival lizard gets too close, bearded dragons can and will bite hard. Sometimes, the bearded dragons will close their mouths and bob their heads up and down to intimidate a perceived threat or competitor. Recent evidence suggests that bearded dragons have primitive venom glands, but it's not known if it serves a defensive function. Bearded dragon bites are not considered harmful to humans and present no long-term health effects.
Body Flattening and Spines
Concurrent with their gaping and beard displays, bearded dragons will flatten their bodies. This makes the bearded dragons look much larger, hopefully dissuading would-be predators. Though the spikes are not sharp, they appear like formidable weapons, and predators may shy away from such a prickly package.
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