The Asian water dragon — also called the Thai, Chinese or green water dragon — is a dark to bright green lizard with high horn scales that run from its head to the base of its laterally flattened tail. The tail is banded in brown and green and ends in a fine point. The water dragon uses its tail for balance and leverage when climbing, and whips it to defend against predators.

Water dragons are sexually dimorphic, meaning males and females exhibit different characteristics. Males generally have more vivid coloring than females, including a bright orange to yellow area under the throat with pink tones near the lower jaw. Males also develop larger heads, jowls and crests on the back and neck, and their femoral pores are typically larger than a female's.

Water dragons do not have a dewlap, or throat pouch. They have well-developed legs, and their feet are five-toed with long, thick claws that end in sharp, needle-like points. The front limbs are generally more slender than the back and are used for climbing and grasping branches. The muscular back legs also aid in climbing, as well as swimming and jumping or leaping from object to object. Asian water dragons can also run bipedally.

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

Asian water dragons typically reach lengths of 3 feet (1 meter), with the tail accounting for nearly 70 percent of its body length. Females tend to be slightly smaller than males.

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 and average temperatures of 75 to 85 degrees Fahrenheit (23.8 to 29.4 degrees Celsius). 

Water dragons can live for 10 to 15 years.

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.

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, cockroaches, earthworms and crickets.

These lizards typically live in groups consisting of one male and multiple females, with both sexes establishing territories.

Males court their mates through physical displays, including head bobbing. During mating, the male latches 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 with a pale green to white underside. Light stripes run vertically across each side of their bodies. They also have brown and green banded tails, large eyes and short snouts. 

Threats to the species have not been identified, but they are commonly found in the pet trade. Habitat destruction is also common within their native range, and the permanent bodies of water they rely on are disappearing.

Asian water dragons have been identified as an invasive species in Hong Kong, likely due to the release of unwanted pets.

Reptile Discovery Center staff at the Smithsonian's National Zoo have identified facultative parthenogenesis, the ability of a sexually reproducing species to sometimes produce offspring asexually, in this species.