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Description:
This unusual mid-sized
stocky agamid lizard has prominent spines along its sides and a large, essentially triangle-shaped head. Forming a sort of
shield around the snout is a spiney jaw pouch which, when swollen, looks like a beard and makes any predator think twice before
attacking. This wide-ranging species shows considerable geographic variation; its basic color varies from shades of brown,
gray, and reddish-brown to bright orange. The ventral surface ranges from pale to dark gray, with white elongated spots edged
with black. Mature males have dark "beards" which become black during courtship and breeding. Adults can grow as large as
ten inches in body length or two feet in total length, including the tail. Males are larger than females.
Diet:
Bearded
dragons are omnivorous and consume many types of insects, small vertebrates, and vegetation including fruits and flowers.
Life Cycle/Social Structure:
Sexual maturity is reached at one to two years of age. Mature females typically lay clutches of eleven to sixteen oblong
leathery eggs in early summer. The eggs are laid in nests dug in sandy soil and the unattended young hatch 3 months later.
Special Adaptations:
A bulky body and the habit of basking allows them to store heat, making it possible to operate at lower temperatures
than other lizards. They can also survive higher temperatures for several hours, since they can regulate body temperature
by evaporation.
Interpretive Information:
When
intimidated, they flatten their bodies and stand erect with mouth gaping. The light-colored mouth lining, spines bordering
the lower jaw and puffed-out blackish beard give a formidable appearance. This defensive display has earned these lizards
the common name of "bearded dragon".
Aggressiveness
to other members of the group is shown through "body language". The tip of the tail is slightly curved at the end and the
head is bobbed rapidly. Submission is signaled by rotating the arms in a full circular motion, which looks a bit like waving.
Ritualistic sparring matches take place in which both animals are in flat postures, beards and tails up and outward; they
circle each other, biting at one another's tail, but usually no damage is done.
Their ability
to change shades of color, from light to dark, helps them to regulate body temperature. Color changes can also depend on emotional
state, and may also be used for concealment. When injured, sick, or dying the back becomes black and the legs pale yellow.
Australian
desert lizards often make their escape by rising on their hind legs and running bipedally. They cannot run as fast as when
using four feet, but perhaps this behavior aids in temperature control. They lift their bodies from the hot ground to lose
the heat they generate in running. This reduces the amount of heat they take in from the ground and increases the cooling
airflow over their bodies. |
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