Draco (lizard)
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Draco is a genus of agamid lizards[1] that are also known as flying lizards, flying dragons or gliding lizards. These lizards are capable of gliding flight via membranes that may be extended to create wings (patagia), formed by a support structure from an enlarged set of ribs.[2] They are arboreal insectivores.
While not capable of powered flight they often obtain lift in the course of their gliding flights. Glides as long as Script error: No such module "convert". have been recorded, over which the animal loses only Script error: No such module "convert". in height which makes for a glide ratio of 6:1. This is done by a lizard of only around Script error: No such module "convert". in total length, tail included.[3] They are found across Southeast Asia and Southern India and are fairly common in forests, areca gardens, teak plantations and shrub jungle.
History of discovery
Carl Linnaeus described the genus in 1758, with the type species being Draco volans. The name of the genus is from the Latin term for dragons of mythology. Some scholars as late as the early-mid 20th century who had not seen the animal in person doubted its flight capabilities or whether the patagia played a significant role in the gliding, but research in the late 1950s firmly established the gliding function of the patagia.[4]
Distribution and habitats
Species of Draco are widely distributed in the forests of Southeast Asia, with one species, Draco dussumieri, inhabiting Southern India.[5]
Members of Draco are primarily arboreal, inhabiting tropical rainforests, and are almost never found on the forest floor.[4]
Overall description
They are insectivorous, primarily feeding on eusocial insects such as ants and termites.[6] The colour of the patagium is strongly correlated to the colour of falling leaves in their range, which complements their cryptic camouflage resembling tree bark; both are likely to be camouflage against predatory birds.[7]
Gliding
The lizards are well known for their "display structures" and ability to glide long distances using their wing-like, patagial membranes supported by elongated thoracic ribs to generate lift forces.[8] The hindlimbs in cross section form a streamlined and contoured airfoil, and are also probably involved in generating lift.[4] Gliding is both used to escape predators, and as the primary means of moving through their forest habitat.[4] The folding and unfolding of the membrane is controlled by the iliocostalis and intercostal muscles, which in other lizards are used to control breathing. At takeoff, the lizard jumps and descends headfirst, orientating itself so that the underside of the body is parallel to the ground. During flight, the back arches, forming the patagium into a cambered surface, and the forelimbs grab the front of the patagium, forming a straight front edge to the aerofoil. The forelimbs are used to manipulate the patagium in order to adjust the trajectory during flight. Maximum gliding speeds have been found to be between 5.2 and 7.6 metres per second, depending on the species. During the landing process, the glide is mostly horizontal.
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Takeoff and initial stages of gliding, slowed down 10x, showing the attachment of the forelimbs to the gliding membrane
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Landing, slowed down 20x
Immediately before landing, the forelimbs release the patagium. The landing is forefeet-first, followed by hindfeet.[9] The shape of the gliding membrane does not correlate with body size, meaning the larger species have proportionately less lift-generating surface area and consequently higher wing loading.[10]
Life history
Draco lizards are highly territorial, with the home range consisting of one or a few trees. The trees are actively guarded by males, with territory-less males searching the forest landscape in search of vacant areas. Experimental studies have determined that suitable unoccupied territories were claimed within a few hours of the removal of a dominant male. Females move freely through the territories. The patagium is used as a display structure during courtship and territorial disputes between rival males, alongside the opening of a brightly-colored dewlap that contrasts with their camouflaged body scalation.[4] The dewlap is translucent, and deliberately orientated perpendicular to the orientation of the sun during display in order to enhance visibility.[11] Draco lizards are sexually dimorphic, with females being larger than males.[12][13] The only time a female flying lizard ventures to the ground is when she is ready to lay her eggs. She descends the tree she is on and makes a nest hole by forcing her head into the soil. She then lays a clutch of 2–5 eggs before filling the hole and guards the eggs for approximately 24 hours, but then leaves and has nothing more to do with her offspring.[3]
Phylogenetics
Within Agamidae, Draco is a member of the subfamily Draconinae. Within Draconinae, Draco is most closely related to the genera Japalura and Ptyctolaemus.[14]
Species
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The following 41 species are recognized:[1][15]
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- Draco abbreviatus Hardwicke & Gray, 1827Script error: No such module "Check for unknown parameters". – Singapore flying dragon
- Draco beccarii W. Peters & Doria, 1878Script error: No such module "Check for unknown parameters".[16]
- Draco biaro Lazell, 1987Script error: No such module "Check for unknown parameters". – Lazell's flying dragon
- Draco bimaculatus Günther, 1864Script error: No such module "Check for unknown parameters". – two-spotted flying lizard
- Draco blanfordii Boulenger, 1885Script error: No such module "Check for unknown parameters". – Blanford's flying dragon, Blanford's flying lizard, Blanford's gliding lizard
- Draco boschmai Hennig, 1936Script error: No such module "Check for unknown parameters".
- Draco caerulhians Lazell, 1992Script error: No such module "Check for unknown parameters".
- Draco cornutus Günther, 1864Script error: No such module "Check for unknown parameters".
- Draco cristatellus Günther, 1872Script error: No such module "Check for unknown parameters". – crested flying dragon
- Draco cyanopterus W. Peters, 1867Script error: No such module "Check for unknown parameters".
- Draco dussumieri A.M.C. Duméril & Bibron, 1837Script error: No such module "Check for unknown parameters". – Indian flying lizard, Western Ghats flying lizard, southern flying lizard
- Draco fimbriatus Kuhl, 1820Script error: No such module "Check for unknown parameters". – fringed flying dragon, crested gliding lizard
- Draco formosus Boulenger, 1900Script error: No such module "Check for unknown parameters". – dusky gliding lizard
- Draco guentheri Boulenger, 1885Script error: No such module "Check for unknown parameters". – Günther's flying lizard, Guenther's flying lizard
- Draco haematopogon Gray, 1831Script error: No such module "Check for unknown parameters". – red-bearded flying dragon, yellow-bearded gliding lizard
- Draco indochinensis M.A. Smith, 1928Script error: No such module "Check for unknown parameters". – Indochinese flying lizard, Indochinese gliding lizard
- Draco iskandari McGuire et al., 2007Script error: No such module "Check for unknown parameters".
- Draco jareckii Lazell, 1992Script error: No such module "Check for unknown parameters".
- Draco lineatus Daudin, 1802Script error: No such module "Check for unknown parameters". – lined flying dragon
- Draco maculatus (Gray, 1845)Script error: No such module "Check for unknown parameters". – spotted flying dragon
- Draco maximus Boulenger, 1893Script error: No such module "Check for unknown parameters". – great flying dragon, giant gliding lizard
- Draco melanopogon Boulenger, 1887Script error: No such module "Check for unknown parameters". – black-bearded gliding lizard, black-barbed flying dragon
- Draco mindanensis Stejneger, 1908Script error: No such module "Check for unknown parameters". – Mindanao flying dragon, Mindanao flying lizard
- Draco modiglianii Vinciguerra, 1892Script error: No such module "Check for unknown parameters". – lined flying dragon
- Draco norvillii Alcock, 1895Script error: No such module "Check for unknown parameters". – Norvill's flying lizard
- Draco obscurus Boulenger, 1887Script error: No such module "Check for unknown parameters". – dusky gliding lizard
- Draco ornatus (Gray, 1845)Script error: No such module "Check for unknown parameters". – white-spotted flying lizard
- Draco palawanensis McGuire & Alcala, 2000Script error: No such module "Check for unknown parameters".
- Draco punctatus Boulenger, 1900Script error: No such module "Check for unknown parameters". – punctate flying dragon
- Draco quadrasi Boettger, 1893Script error: No such module "Check for unknown parameters". – Quadras's flying lizard
- Draco quinquefasciatus Hardwicke & Gray, 1827Script error: No such module "Check for unknown parameters". – five-lined flying dragon, five-banded gliding lizard
- Draco reticulatus Günther, 1864Script error: No such module "Check for unknown parameters".
- Draco rhytisma Musters, 1983Script error: No such module "Check for unknown parameters".
- Draco spilonotus Günther, 1872Script error: No such module "Check for unknown parameters". – Sulawesi lined gliding lizard
- Draco spilopterus Wiegmann, 1834Script error: No such module "Check for unknown parameters". – Philippine flying dragon
- Draco sumatranus Schlegel, 1844Script error: No such module "Check for unknown parameters". – common gliding lizard
- Draco supriatnai McGuire et al., 2007Script error: No such module "Check for unknown parameters".
- Draco taeniopterus Günther, 1861Script error: No such module "Check for unknown parameters". – Thai flying dragon, barred flying dragon, barred gliding lizard
- Draco timoriensis Kuhl, 1820Script error: No such module "Check for unknown parameters". – Timor flying dragon
- Draco volans Linnaeus, 1758Script error: No such module "Check for unknown parameters". – common flying dragon
- Draco walkeri Boulenger, 1891Script error: No such module "Check for unknown parameters".
Nota bene: a binomial authority in parentheses indicates that the species was originally described in a genus other than Draco.
Similar prehistoric reptiles
Several other lineages of reptile known from the fossil record have convergently evolved similar gliding mechanisms consisting of a patagium or plate flanking the torso; the weigeltisaurids are the oldest of these, living in the Late Permian from around 258 to 252 million years ago. Other lineages include the Triassic kuehneosaurids and Mecistotrachelos, and the Cretaceous lizard Xianglong.[4][9]
See also
- Flying and gliding animals
- Chrysopelea gliding snake
References
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- ↑ a b Draco at the Reptarium.cz Reptile Database. Accessed 8 June 2021.
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- ↑ a b Piper, Ross (2007). 'Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals'. Santa Barbara, California: Greenwood PressScript error: No such module "Unsubst"..
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- ↑ Script error: No such module "Citation/CS1".
- ↑ "Draco ". Dahms Tierleben. www.dahmstierleben.de.
- ↑ Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. Template:ISBN. (Draco beccarii, p. 21).
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Further reading
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- Goin CJ, Goin OB, Zug GR (1978). Introduction to Herpetology, Third Edition. San Francisco: W.H. Freeman & Company. xi + 378 pp. Template:ISBN. (Genus Draco, pp. 41, 86, 112, 279, 288).
- Script error: No such module "citation/CS1". 33 pp.
- Linnaeus C (1758). Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio Decima, Reformata. Stockholm: L. Salvius. 824 pp. (Genus Draco, p. 199).
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- Read on vastlyimportant