Here be Dragons

14th August is World Lizard Day! This year we are going to be featuring dragons.

File:Friedrich-Johann-Justin-Bertuch Mythical-Creature-Dragon 1806.jpg
No not that kind of dragon…

Dragons are found in one form or another in nearly every culture in the world. And every dragon has its style; fire-breathers, gold-hoarders, princess-stealers, and more. But these dragons are of lore. We are going to meet some real-life dragons today, and we don’t even mean the giant varanids of the Indonesian islands.

Say hello to some of the tiniest dragons ever: the Agamids of the genus Draco .

Draco sumatranus JT
A male Sumatran Flying Dragon (Draco sumatranus) flagging. Flagging (the extension of the brightly coloured dewlap) acts as a cue to attract females and to ward off rival males [1].  Photo Credit: Jonathan Tan

Draco lizards belong to the family Agamidae. Other members of this family include Changeable Lizards (Calotes versicolor) and Green Crested Lizards (Bronchocela cristatella), both of which are commonly found in Singapore.

A Green Crested Lizard, pictured here doing a split! Photo Credit: Emmanuel Goh

Globally, there are more than 40 extant Draco species. Three of them call our little island (and specifically our trees) home. They are the Sumatran Flying Dragon (D. sumatranus), the Black-bearded Flying Dragon (D. melanopogon) and the Five-banded Flying Dragon (D. quinquefasciatus).

The Black-bearded Flying Dragon (Left), and the Five-banded Flying Dragon (Right)
Photo Credit: Bernard DUPONT (CC-BY-SA 2.0)

But, what do these tiny tree-dwelling lizard [2] have in common with the dragons of myths and lore?

The ability to take to the air. Well, almost.

PSM V36 D830 Flying dragons of malaysia.jpg
Flying dragons of Malaysia, Armand-Lucien Clément (1848-1921)
Published in Popular Science Monthly, Volume 36

Life in the trees is not all breezy and filled with birdsong. To some birds, the Draco is a decent-sized meal. And when a predator in the treetops confronts you, the only way is down. Jumping off a tree is much faster than attempting to run down its length!

While it is not the real wing-powered flight of Smaug, Toothless, or Drogon, Draco lizards take to the air and glide with expanded flaps of membranous skin stretched between elongated and flexible ribs. This morphological adaptation, known as a patagium, helps increase this skinny lizard’s surface area and slows its descent, preventing an unfortunate splat. With muscles and rib bones running throughout its length [3], the patagium can be actively controlled, making the Draco an active and agile glider!

A moulting Black-bearded Flying Dragon. Note the expansion of the ribcage!
Photo Credit: Ron Yeo <link>

In addition to their patagium, Draco have improved their gliding skills by evolving flatter limbs [4] and a long dewlap [5]. These add to the increased surface area of the airborne lizard. With such amazing adaptations, Draco glides lose very little height while still travelling very far! Records include one that spanned over 60 metres, where the lizard only lost a mere 10 metres in height [6]!

So, where might one encounter these tiny dragons in Singapore? While the Black-bearded Flying Dragon and the Five-banded Flying Dragon prefer the matured primary forests of our Central Nature Reserves, the Sumatran Flying Dragon has adapted well to urban habitats and are readily found in our parks, gardens, and forest fringes!

While not the fire-breathing dragons of stories or the giant Komodo dragons, these small creatures have no trouble inspiring awe. Remember to keep an eye out on the treetops the next time you take a walk. You just might get to see a Draco living up to its majestic name.


References

  1. Mori, A., & Hikida, T. (1994). Field Observations on the Social Behavior of the Flying Lizard, Draco volans sumatranus, in Borneo. Copeia, 1994(1), 124-130. doi:10.2307/1446678
  2. Herre, Albert W. (1958). “On the Gliding of Flying Lizards, Genus Draco “. Copeia. 1958 (4): 338–339. doi:10.2307/1439979
  3. Mcguire, J. A., & Dudley, R. (2011). The Biology of Gliding in Flying Lizards (Genus Draco) and their Fossil and Extant Analogs. Integrative and Comparative Biology, 51(6), 983-990. doi:10.1093/icb/icr090
  4. Mcguire, J. (2003). Allometric Prediction of Locomotor Performance: An Example from Southeast Asian Flying Lizards. The American Naturalist, 161(2), 337-349. doi:10.1086/346085
  5. Smith, Hobart Muir (1995). Handbook of Lizards: Lizards of the United States and of Canada. Cornell University Press. p. 27.
  6. Piper, Ross (2007). ‘Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals’. Santa Barbara, California: Greenwood Press.

Published by Scribbles of a Zoology Student

Zoology Student. Freelance Photographer. Passionate Culinarian. Avid Bibliophile. Armed with a iPhone 6S and/or Canon 60D. Bearded.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Create your website with WordPress.com
Get started
<span>%d</span> bloggers like this: