The Water Dragon describes large, semi-aquatic lizards of the genus Physignathus (Asian Water Dragon) and the closely related genus Intellagama (Australian Water Dragon). These reptiles are native to the freshwater habitats of Southeast Asia and Eastern Australia. Their physical appearance is highly adapted to their arboreal and riverine environment, featuring specific characteristics that allow them to be efficient swimmers and climbers.
General Body Structure and Size
The Water Dragon possesses a robust, athletic build that enables its semi-aquatic lifestyle. Adult individuals often reach up to one meter (three feet) in length from snout to the tip of the tail, with males typically growing larger than females. The powerful tail is laterally compressed, meaning it is flattened from side to side, which serves as a highly effective rudder for propulsion when swimming. The tail alone constitutes about two-thirds of the lizard’s total body length.
The body is supported by four strong, well-developed limbs that feature five toes ending in long, curved claws. These claws allow the dragon to grip tree bark and rocks along riverbanks with ease. The skin is covered in small, granular scales, with coloration varying from vibrant green (Asian species) to olive, grey-green, or brown (Australian species). Some individuals display dark transverse bands across the back and tail, providing camouflage.
Defining Features: Crests and Dewlaps
One of the most defining aspects of the Water Dragon’s appearance is the prominent crest of enlarged, spiny scales that runs along its body. This crest begins at the back of the head, known as the nuchal crest, and continues down the center of the back as the dorsal crest. The spines decrease in size as they extend toward the tail, emphasizing the lizard’s large head and neck region. These physical extensions are typically more pronounced and taller in mature males.
Beneath the head, the Water Dragon features a noticeable fold of loose skin known as a gular pouch, which is often referred to as a dewlap. Both species have this loose skin under the jaw that can be extended during threat or courtship displays. The head itself is distinctly shaped, and a large, visible tympanum (external ear opening) is located just behind the eye.
Differences Between Males and Females
Water Dragons are sexually dimorphic, meaning clear visual differences develop between the sexes as they reach maturity. Males are consistently larger overall, possessing broader, more triangular heads with significantly larger jowls than females. The crests on the head and back are also much more exaggerated in males, featuring longer, more salient spines.
The most striking difference is coloration, particularly during the breeding season. Mature male Australian Water Dragons often develop vivid red or orange flushes on their chest and belly, or colorful blotches of blue, orange, or yellow on the throat. In contrast, females typically retain a duller, more subdued coloration, lacking these intense markings. Female heads remain narrower, and their crests are shorter and less defined.