Water monitor

The Asian water monitor (Varanus salvator), also called common water monitor, is a large varanid lizard native to South and Southeast Asia. It is one of the most common monitor lizards in Asia, ranging from Sri Lanka and coastal northeast India to Indochina, Malay Peninsula, and Indonesian islands where it lives close to water. It is listed as Least Concern on the IUCN Red List. It was described by Laurenti in 1768 and is among the largest squamates in the world. The Asian water monitor is also called Malayan water monitor, common water monitor, two-banded monitor, rice lizard, ring lizard, plain lizard and no-mark lizard, as well as simply 'water monitor'. The local name in Sri Lanka is kabaragoya, denoting a subspecies with distinct morphological features. The water monitor is a large species of monitor lizard. Breeding maturity is attained for males when they are a relatively modest 40 cm (16 in) long and weigh 1 kg (2.2 lb), and for females at 50 cm (20 in). However, they grow much larger throughout life, with males being larger than females. Adults rarely exceed 1.5–2 m (4.9–6.6 ft) in length, but the largest specimen on record, from Sri Lanka, measured 3.21 m (10.5 ft). A common mature weight of V. salvator can be 19.5 kg (43 lb). However, 80 males killed for the leather trade in Sumatra averaged only 3.42 kg (7.5 lb) and 56.6 cm (22.3 in) snout-to-vent and 142 cm (56 in) in total length; 42 females averaged only 3.52 kg (7.8 lb) and 59 cm (23 in) snout-to-vent and 149.6 cm (58.9 in) in total length, although unskinned outsized specimens weighed 16 to 20 kg (35 to 44 lb). Another study from the same area by the same authors similarly estimated mean body mass for mature specimens at 20 kg (44 lb) while yet another study found a series of adults to weigh 7.6 kg (17 lb). The maximum weight of the species is over 50 kg (110 lb). In exceptional cases, the species has been reported to attain 75 to 90 kg (165 to 198 lb), though most such reports are unverified and may be unreliable. They are the world's second-heaviest lizard, after the Komodo dragon. Their bodies are muscular, with long, powerful, laterally compressed tails. The scales in this species are keeled; scales found on top of the head have been noted to be larger than those located on the back. 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 an elongated snout. They use their powerful jaws, serrated teeth and sharp claws for both predation and defense. In captivity, Asian water monitors' life expectancy has been determined to be anywhere between 11–25 years depending on conditions, in the wild it is much less. The Asian water monitor is widely distributed from India, Bangladesh, Sri Lanka, Myanmar and Thailand, Cambodia, Laos, Vietnam, the Chinese Guangxi and Hainan provinces, Malaysia, Singapore to the Sunda islands Sumatra, Java, Bali, Borneo and Sulawesi. It inhabits primarily lowland freshwater and brackish wetlands. It has been recorded up to an altitude of 1,800 m (5,900 ft). Asian water monitors are semiaquatic and opportunistic; they inhabit a variety of natural habitats though predominantly this species resides in primary forests and mangrove swamps. It has been noted that these monitors are not deterred from living in areas of human disturbance. In fact, they have been known to adapt and thrive in agricultural areas as well as cities with canal systems (such as in Sri Lanka, where they are not hunted or persecuted by humans). This species does not thrive in habitats with extensive loss of natural vegetation and aquatic resources. Habitats that are considered to be most important to this species are mangrove vegetation, swamps, wetlands, and altitudes below 1000 meters. Water monitors defend themselves using their tails, claws, and jaws. They are excellent swimmers, using the raised fin on their tails to steer through water. They are carnivores, and consume a wide range of prey. They are known to 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 have been observed eating catfish in a fashion similar to a mammalian carnivore, tearing off chunks of meat with their sharp teeth while holding it with their front legs and then separating different parts of the fish for sequential consumption. In dominantly aquatic habitats their semiaquatic behavior is considered to provide a measure of safety from predators. Paired with their generalist diet, this is thought to contribute to their ecological plasticity. When hunted by predators such as the king cobra (Ophiophagus hannah) they will climb trees using their powerful legs and claws. If this evasion is not enough to escape danger, they have also been known to jump from trees into streams for safety, a tactic similar to that of the green iguana (Iguana iguana). Like the Komodo dragon, the water monitor will often eat carrion. They have a keen sense of smell and can smell a carcass from far away. They are known to feed on dead human bodies. While on the one hand their presence can be helpful in locating a missing person in forensic investigations, on the other hand they can inflict further injuries to the corpse, complicating ascertainment of the cause of death.