Asian Water Dragon

Class: Reptilia
Order: Squamata
Family: Agamidae
Genus and Species: Physignathus cocincinus
  • A green lizard, called an Asian water dragon, standing in mulch
  • a lizard sits on a branch
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Asian Water Dragon

Asian water dragons are bright green lizards found in Thailand, Vietnam, Cambodia, Laos, Burma and southern China. They are adept climbers and strong swimmers and, if necessary, can remain submerged for up to 25 minutes.
Physical Description

Asian water dragons are typically bright green. Their laterally flattened tails have brown bands and end in a fine point. They use their tails for balance and leverage when climbing, and can whip them to defend against predators. High horn scales run from the dragon's head, down the back and to the base of the tail. Water dragons are sexually dimporphic, with males generally exhibiting more vivid colors. Males have an area under the throat that is intensely orange to yellow with pink tones in the lower jaw. They also develop larger heads, jowls and crests on the back and neck, and their femoral pores are somewhat larger than a female's.

Water dragons do not have a typical dewlap or throat pouch. The species has well-developed legs, the front legs generally more slender than the back. Each leg is five-toed with long, thick claws ending in sharp, needle-like points. The water dragon's clawed front legs help it climb and grasp branches. Its muscular back legs also aid in climbing, as well as swimming and jumping or leaping from object to object. Water dragons can also run bipedally.

When nervous or frightened, Asian water dragons seek refuge in the water. They are strong swimmers and, if necessary, can remain submerged for long periods of time—sometimes as long as 25 minutes!

Asian water dragons typically reach lengths of 3 feet (1 meter). Females are typically slightly smaller than males. The water dragon's tail accounts for nearly 70 percent of its body length.
Native Habitat
Asian water dragons are found in Thailand, Vietnam, Cambodia, Laos, Burma and southern China. They generally live around permanent, standing water, such as on banks of rivers, in rainforests and in swamps. They are good climbers and can drop from branches into the water if threatened or startled. Water dragons live in areas with an average humidity level ranging from 80 percent in the morning to 60 percent in the evening. The temperatures average 75 to 85 degrees Fahrenheit (23.8 to 29.4 degrees Celsius). 
Both males and females will occasionally express aggressive behavior toward each other in the form of arm waving, puffing up of the throat, head bobbing and, sometimes, chasing.
Food/Eating Habits
Water dragons prey on rodents, birds, fish and invertebrates, supplementing this diet with vegetation and eggs. Their sticky tongue and small, pointed teeth aid in catching and holding on to prey. At the Smithsonian's National Zoo, Asian water dragons are fed a lizard salad of mixed greens and insects. 
Social Structure
Asian water dragons typically live in groups consisting of one male and multiple females, with both sexes establishing territories.
Reproduction and Development
Males court their mates through physical displays, including head bobbing. During mating, males will latch onto the crest of the female's head. Females lay between six and 15 eggs that hatch after an incubation period of 60 to 75 days. Hatchlings are about 1 inch (2.54 centimeters) from snout to vent and 5 to 6 inches (13 to 15 centimeters) in total length. They are often a brown-green color dorsally and a pale green to white ventrally. Light stripes run vertically across each side of their body. They also have brown and green banded tails, large eyes and short snouts. 

Asian water dragons have not been assessed by the International Union for Conservation of Nature. Threats to the species have not been identified, though they are commonly found in the pet trade. Habitat destruction is also common within their native range. Asian water dragons have been identified as an invasive species in Hong Kong, likely due to the release of unwanted pets.