29-11-2016 SINGAPORE - ASIAN WATER MONITOR (Varanus salvator ssp. salvator)

The Asian water monitor (Varanus salvator) is a large varanid lizard native to South and Southeast Asia. It is one of the most common monitor lizards in Asia and is among the largest squamates in the world.

The bodies of Asian water monitors are muscular, with long, powerful, laterally compressed tails. Water monitors are often defined by their dark brown or blackish coloration with yellow spots found on their underside - these yellow markings have a tendency to disappear gradually with age. This species is also denoted by the blackish band with yellow edges extending back from each eye. These monitors have very long necks and elongated snouts. They use their powerful jaws, serrated teeth, and sharp claws for both predation and defense.

Asian water monitors are widely distributed from India, Bangladesh, Sri Lanka, Myanmar and Thailand, Cambodia, Laos, Vietnam, the Chinese Guangxi and Hainan provinces, Malaysia, and Singapore to the Sunda islands Sumatra, Java, Bali, Borneo, and Sulawesi. They inhabit a variety of natural habitats though predominantly these lizards reside in primary forests and mangrove swamps. They may also thrive in agricultural areas as well as cities with canal systems. Habitats that are considered to be most important to this species are mangrove vegetation, swamps, and wetlands.

Asian water monitors are semiaquatic; they are excellent swimmers, using the raised fin on their tails to steer through water. They are diurnal creatures. During the night or when just resting monitors hide in trees, under bushes, large roots, or cavities in between rocks. They also make their burrows which often lie close to the river or stream and are partially flooded. Asian water monitors defend themselves using their tails, claws, and jaws. When hunted by predators such as the King cobra they will climb trees using their powerful legs and claws. If this evasion is not enough to escape danger, they may jump from trees into streams for safety.

The possibility of venom in the genus Varanus is widely debated. Previously, venom was thought to be unique to Serpentes (snakes) and Heloderma (venomous lizards). The aftereffects of a Varanus bite were thought to be due to oral bacteria alone, but recent studies have shown venom glands are likely to be present in the mouths of several, if not all, of the species. The venom may be used as a defensive mechanism to fend off predators, to help digest food, to sustain oral hygiene, and possibly to help in capturing and killing prey.

Asian water monitors are carnivores and consume a wide range of prey. They eat fish, frogs, rodents, birds, crabs, and snakes. They have also been known to eat turtles, as well as young crocodiles and crocodile eggs. Water monitors will also often eat carrion. They have a keen sense of smell and can smell a carcass from far away.

Asian water monitors breed from April until October. Females lay their eggs a month after mating usually in rotting logs or tree stumps. A clutch usually contains about 10-40 eggs which are incubated during 6-7 months. The young are fully developed and independent at birth. Males become reproductively mature when they are about 1 m in size and females are reproductively mature at about 50 cm.