Central bearded dragon
Central bearded dragon | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Suborder: | Iguania |
Family: | Agamidae |
Genus: | Pogona |
Species: | P. vitticeps
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Binomial name | |
Pogona vitticeps Ahl, 1927
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Native distribution |
The central bearded dragon (Pogona vitticeps), also known as the inland bearded dragon, is a species of agamid lizard found in a wide range of arid to semiarid regions of eastern and central Australia.[2]
Taxonomy
Pogona vitticeps was first described by German zoologist Ernst Ahl in 1926, who placed it in the genus Amphibolurus.[3][4]
Description
Mature bearded dragons can reach a total length of around 60 cm (24 in), or two feet, with the tail accounting for more than half of that. Some
Somewhat like chameleons, bearded dragons are capable of inducing moderate changes in coloration based on mood. Additionally, they can slightly raise the pointed scales that run along either side of their throat, neck, head and torso by inhaling air into their lungs to maximum capacity, thus appearing larger to predators. The sharp-looking growths and protrusions are, in actuality, quite soft and delicate to the touch, but may be off-putting to predators such as birds of prey, foxes, feral dogs or dingos. When cornered or threatened, a bearded dragon will flatten its body against the ground, expand its rib cage outwards, open its mouth and expand its "beard" (guttural pouch; similar to a frilled lizard’s defense tactics, albeit on a smaller scale). The guttural pouch is what essentially earns the species its nickname of "beardie", and can darken in color when threatened or during courtship or territorial displays. Both of these characteristics appear similar to a human's beard. Males typically have a darker "beard" than females, and during mating season and courtship it will typically darken to near-black. The bearded dragon, like most agamid lizards, has strong legs which enable it to lift its body completely off the ground while it moves. This is done to reduce heat absorption from the hot ground, and facilitates airflow under the body.
A study conducted in 2014 established the existence of endogenous circadian rhythm in pigmentation changes in P. vitticeps; if exposed to sun, the dorsal skin of the lizard becomes darker, and if exposed to darkness, it becomes lighter. Under constant darkness (i.e. in the subjective night), the lizard's dorsal skin becomes the lightest.[7]
Many species of Pogona have a parietal eye (or "third eye"), a photoreceptor found on the centre of the forehead. This unique feature is responsible for thermoregulation and hormone regulation, and possibly helps the lizards make decisions based on the seasons, weather, etc.[8] A March 2020 study of the central bearded dragon found that light-dependent magnetoreception occurs when light with a wavelength under 580 nanometers enters the parietal eye.[9][10]
Ecology and behaviour
This section needs additional citations for verification. (November 2018) |
P. vitticeps is native to
P. vitticeps are opportunistic omnivores. They live in areas where food may be hard to find, thus they are not particularly finicky eaters. Their stomachs are large enough to accommodate significant quantities of vegetation, fruits, insects, worms, and the occasional small rodent or lizard.[11] Favored insect prey includes crickets, grasshoppers, beetles, caterpillars, moths, butterflies, or any insect that can comfortably be swallowed.
Bearded dragons do not vocalize, except to hiss softly when threatened. Instead, they communicate through colour displays, posture, and physical gestures, such as arm waving and head bobbing. Bearded dragons are not social animals, but will sometimes gather in groups, especially in popular feeding or basking areas. At these times, a distinct hierarchy will emerge: the highest-ranking animals will take the best – usually the highest or sunniest – basking spots, and all other individuals arrange themselves lower down.[12] If a low-ranking animal tries to challenge one of the dominant dragons, the dominant animal will demonstrate its superiority by bobbing its head and inflating its beard, at which point the challenger may signal submission by waving one of its arms in a slow or fast circle. If the low-ranking dragon does not submit, it will return the head bob, and a standoff or fight may ensue.
The head bob gestures are:[13]
- Slow bowing motion – often used by adult females to signal submission to a male
- Fast bob – used by males to signal dominance (often accompanied by an inflated and/or blackened beard)
- Violent bob – used by males just before mating; much more vigorous, and usually sets the animal's whole body in motion
- Both males and females will occasionally do fast and violent head bobs, which shows they are stressed out and need to be isolated.
The male will only wave to show submission to a dominant male, whereas the female will wave, followed by a slow head bob, to show she is ready to mate. Gravid females will often refuse the advances of a male by chasing him and lying on his back.
When under direct attack, the central bearded dragon opens its mouth to display its yellow membranes and extend its beard.[14] It darkens the colour of its skin and flattens its body, and will hiss and make small jumps towards the attacker. Bearded dragons are not known to attack humans.[5]
Adult male bearded dragons can bite more forcefully than adult females and this difference is associated with greater head dimensions.[15]
Bearded dragons have been shown to be able to learn from watching the behaviour of conspecifics. An experiment demonstrated that after one individual was trained to open a door to reach a food item, most other bearded dragons watching this action were able to perform it as well.[16]
Reproduction
The age of sexual maturity has not been measured, although it is estimated to be about one or two years.
Courtship involves the male "head bobbing" to display dominance. If the female displays submissive behaviour, the male will use his mouth to grab the back of the female's head and the male will also wrap his front legs around the female's upper torso to keep her from moving. Copulation and insemination are quick. The gestation period averages about a month and a half.
Thermally induced sex reversal
A 2015 study showed that high-temperature incubation of eggs transforms genetically male individuals into functional females.[17] Normally their sex is determined genetically. Males have ZZ sex chromosomes, females ZW. However, when their eggs are incubated at temperatures above 32 °C (90 °F) some genetic males are born female. These females are fertile, sometimes producing more eggs than the ZW females.[18] As juveniles, the sex reversed ZZ females resemble ZZ males with respect to relative tail length and boldness.[19] However, as adults sex-reversed ZZ females lack the larger head and greater bite force of ZZ males and more closely resemble ZW females.[15]
Captive breeding
Several of the Pogona genus are bred in captivity as pets; the two most popular are this species and the Rankin's dragon (Pogona henrylawsoni).[20][21] The majority of captive-bred bearded dragons today are thought to have originated from stock illegally exported from Australia during the 1970s.[22] Australia has since prohibited the importation and exportation of its native species, thus guaranteeing any bearded dragons found today outside of Australia have been captive-bred, hand-raised and socialized with human interaction from a very young age. The anti-exportation policies in Australia also ensures that bearded dragons (and indeed all Australian species found abroad) are not forcibly taken or poached from the wild and shipped around the globe via the black market—as is the case with Madagascar's rare and sensitive chameleons, geckos and frogs, for example.
However, captive bearded dragons worldwide are threatened by
When the female is ready to lay eggs, she will generally stop eating, and spend most of her time trying to dig.
A morph with underdeveloped dorsal scales is popular as a terrarium pet under the name of "leatherback bearded dragon".[24]
References
- . Retrieved 12 November 2021.
- ^ a b Pest Risk Assessment - Central bearded dragon (PDF), Tasmania Department of Primary Industries, Parks, Water and Environment, May 2011, archived from the original (PDF) on 17 February 2023
- ^ Ahl, E. 1926. Neue Eidechsen und Amphibien. Zool. Anz. 67: 186–192
- ^ Pogona vitticeps at the Reptarium.cz Reptile Database
- ^ a b c Doneley, B. (2006). "Caring for the bearded dragon". Proceedings of the North American Veterinary Conference. 20: 1607–1611.
- ^ "Reptile Care and Husbandry: Bearded Dragons". Reptile Specialists LLC. 2008. Archived from the original on 2012-02-19.
- PMID 25354192. Retrieved 29 October 2014.
- ^ Nairn, Tina (2020-06-05). "Bearded Dragons Third Eye [how it changes behaviors & care]". Retrieved 2023-01-25.
- S2CID 235779557.
- ^
Nishimura, Tsutomu (2020-03-15). "The Parietal Eye of Lizards (Pogona vitticeps) Needs Light at a Wavelength Lower than 580 nm to Activate Light-Dependent Magnetoreception". S2CID 212752273.
- ^ "Pogona vitticeps (Central Bearded Dragon)". Animal Diversity Web.
- ^ "BEARDED DRAGON (Pogona vitticeps)". www.lihs.org. Retrieved 2020-08-16.
- ^ "Understand Your Bearded Dragon Behaviors and Body Languages". The Pet Enthusiast. 2019-10-11. Retrieved 2019-12-30.
- ^ Witten, G.J. (1993). No. 29 Family Agamidae. Fauna of Australia. Volume 2A. AGPS Canberra
- ^ S2CID 211122728.
- ^ John Virata (1 October 2014). "Bearded Dragon Lizards Are Smarter Than You Might Think!". Reptile Magazine.
- S2CID 1741119.
- IFLScience. 8 June 2016.
- PMC 4920310.
- ^ "Pet Profile – Bearded Dragons". The Pet Show. Australian Broadcasting Corporation. 2008.
- ISBN 978-1-920694-74-6.
Western Bearded Dragon, Pogona minor minor
- ^ Steve Grenard – Your Happy Healthy Pet: Bearded Dragon 2nd Edition, page 35
- ISSN 1055-937X.
- ^ "What Is A Leatherback Bearded Dragon?". BeardiesRule. 23 April 2022.
Further reading
- Kis, Anna; Huber, Ludwig; Wilkinson, Anna (January 2015). "Social learning by imitation in a reptile (Pogona vitticeps)" (PDF). Animal Cognition. 18 (1): 325–331. S2CID 18161181. Retrieved 30 April 2015.