Bearded dragons (Pogona vitticeps) are sun-loving lizards native to Australia. They lack sufficient ground speed and fighting capacity to deter the dingoes and other lizards that prey on them, but the sand-colored reptiles do have a number of distinctive physical behaviors that are linked to self-defense. They tolerate handling, so "beardies" are suitable for keeping as pets.
Stroke a pet bearded dragon along the back and you’ll feel a number of spines. These spines are incapable of causing much harm, as they are soft and flexible. In fact, the spines are just for show. The purpose of the spines is to deter a predator from viewing the bearded dragon as a potential meal. It is unlikely that the spines represent a threat to a would-be predator, but they would make the bearded dragon appear to be a rather painful meal to digest. His rubbery spikes are an example of evolutionary mimicry: The bearded dragon has evolved a physical feature that resembles the feature of another animal. While the feature has no defensive capability, predators think it does, and avoid the prey critter.
When threatened, a bearded dragon may attempt to inflate his body in order to appear bigger. Since his short legs do not enable him to run quickly, he is typically incapable of using speed to escape a predator. Instead, his best means of defense when cornered is to try to trick his adversary into thinking he is larger and stronger than he is. As well as making his body look larger, inflation makes his spines appear more rigid, and potentially painful, than they really are.
Bearded dragons get their name from the collection of spines that grow around the underside of their chins. By opening their mouths good and wide, bearded dragons are able to make their beards appear larger than they actually are. Often, they gape their mouths while inflating their bodies.
Flattening the Body
Bearded dragons flatten their bodies and open their jaws to make themselves appear larger. This approach is different from bodily inflation, whereby they attempt to appear bulkier and stronger. By flattening their bodies, the bearded dragons are attempting to appear to be wider than they are, with the probable intention of giving their spines more visibility and making themselves appear difficult to digest.