Table of Contents
Overview
Distribution
Range Description
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Geographic Range
Varanus salvator occurs throughout much of southern Asia, from India in the west to the Philippines and the Indo-Australian islands in the east.
Biogeographic Regions: oriental (Native )
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Distribution: Sri Lanka, NE India (incl. Nicobar Islands, Andaman Islands), Bangladesh, Myanmar (= Burma), Cambodia, Laos, Vietnam, S China (Hong Kong, Guangdong, Hainan, Guangxi, S Yunnan), Thailand (incl. Phuket), Malaysia (incl. Pulau Tioman, Johor: Pulau Besar), Singapore, Indonesia (Borneo, Sumatra, Nias, Enggano, Bangka, Kalimantan, Java, Bali, Lombok, Sumbawa, Flores, Wetar, Sulawesi), USA (possibly introduced to Florida) adamanensis: Andaman Islands;
Type locality: Port Blair, Andaman Islands. bivittatus: Java, Bali, Lombok, Sumbawa, Flores, Ombai (Alor), Wetar and some neighbouring islands within the Sunda arch, Indonesia;
Type locality: Java (designated by MERTENS 1959). komaini: Thailand.
Type locality: Amphoe La-ngu, Satun Prov., Thailand, and Thai-Malaysian bodeer area. macromaculatus: Thailand, Cambodia, Laos, Vietnam, Myanmar, Bangladesh, Malaysia, Indonesia (Sumatra, Borneo) salvator: restricted to Sri Lanka (KOCH et al. 2007);
Type locality: America (in error); emended to "Ceylon" (= Sri Lanka) by Mertens (1959). ziegleri: Obi Island, Indonesia;
Type locality: Kali Telaga, Obi Island, Maluku Province, Central Indonesia.
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Physical Description
Morphology
Physical Description
Varanus salvator is reported to grow to 3 meters in length, but most adults are 1.5 meters long at most. Individuals have a black temporal band edged with yellow that extends back from each eye. The neck of this monitor is very long with an elongated snout. The nostrils are close to the end of the nose. The tail is laterally compressed and has a dorsal keel. The scales on the top of the head are relatively large, whil those on the back are smaller in size and are keeled.
The color of the Water Monitor is usually dark brown or blackish, with yellow spots on the underpart of the lizard. The yellow markings on the species tend to diminish as the individual becomes older (Steel, 1996).
- Steel, R. 1996. Living Dragons. London: Ralph Curtis Books.
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Ecology
Habitat
Habitat and Ecology
Although the species may inhabit all the habitats listed above in at least parts of its range, they cannot all be considered equally as important. The habitats considered most important to this species are mangrove vegetation, swamp and wetlands at altitudes of below 1,000 m (Gaulke and Horn 2004).
Systems
- Terrestrial
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Habitat
Varanus salvator is semi-aquatic and has a wide range of habitats. They are frequently seen on river banks and in swamps. The Water Monitor is a water-dependent species and has been known to cross large stretches of water, explaining its wide distribution.(Taylor, 1966).
Though also found on flat land, a typical burrow is in a river bank. The entrance starts on a downward slope but then increases forming a shallow pool of water. The average length is about 9.5 m, the average depth is about 2 m, and the average temperature is around 26 degrees Celsius (Traeholt, 1995).
Terrestrial Biomes: forest
Aquatic Biomes: rivers and streams
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Trophic Strategy
Food Habits
The Water Monitor is an extreme carnivore. This means that the lizard will eat about any animal that it believes it can consume (see additional comments). Among some of the common prey includes: birds and their eggs, small mammals (especially rats), fish, lizards, frogs, snakes, juvenile crocodiles, and tortoises. Like the Komodo Dragon, the Water Monitor has been known to dig up corpses of humans and devour them as well.
The primary hunting technique used by Varanus salvator, as well as by other monitors, is characterized by 'open pursuit' hunting, rather than stalking and ambushing. The lizard is very fast for it size due to its powerful leg muscles (Shine & Harlow, 1996).
While hunting for aquatic prey, Varanus salvator can remain submerged for up to 30 minutes (Taylor, 1963).
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Life History and Behavior
Life Expectancy
Lifespan/Longevity
Average lifespan
Status: captivity: 10.6 years.
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Lifespan, longevity, and ageing
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Reproduction
Reproduction
Males are normally larger than the females, usually twice as large in mass. The maturation of the male occurs when the individual is about 1-meter in size and the female at about 50-cm. The breeding season begins in April and lasts until October. However the testes of the male are the largest during April and the female is more receptive, thus there is an increase in reproductive success the earlier fertilization takes place (Shine, 1996).
Larger females produce a larger clutch size than smaller individuals. The eggs are usually deposited along rotting logs or stumps.
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Molecular Biology and Genetics
Molecular Biology
Barcode data: Varanus salvator
There are 3 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
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Statistics of barcoding coverage: Varanus salvator
Public Records: 3
Species: 3
Species With Barcodes: 1
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
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Conservation Status
Although killed extensively for its skin, this species seems to be resilient. It has been proposed that this is because large females, who produce larger clutches, are avoided by the leather trade (Steel, 1996).
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
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Trends
Population
Population Trend
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Threats
Threats
Apart from direct utilization of this species, destruction of habitats for oil palm plantations, farming, timber, and firewood have caused declines in population numbers in some areas, particularly in Borneo and Sulawesi, where the species in this complex seem to be less tolerant of human activities and do not generally thrive in agricultural regions (S. Sweet pers. comm.). It is likely that habitat loss was the main reason for population declines in those areas where this species has disappeared (D. Bennett pers. comm.).
In Sri Lanka, the species is not hunted for meat due to the belief that its meat is toxic, but the oil extracted from it is used for traditional medicine and witchcraft. However, this is a very trivial threat compared to the numbers lost from road traffic (R. Somaweera pers. comm.). Since the species can tolerate very polluted habitats, and thrive in areas with high anthropogenic activity, habitat degradation and loss may not be major threats to this species in Sri Lanka (R. Somaweera pers. comm.).
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Management
Conservation Actions
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Positive
Skins of Varanus salvator are used for dietary protein, ceremonies, medicine, and leather goods. Annual trade in these skins may reach more than 1 million whole skins a year, mostly in Indonesia for the leather trade. Medium-sized individual are preferred because the skin of large animals is too tough and thick to shape (Shine, 1996).
There is small trade in live monitors, but they are not suitable pets for a majority of the owners.
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Wikipedia
Water monitor
- For large firefighting devices, see Deluge gun.
- For the Australian species with a similar common names, see Mertens' Water Monitor and Mitchell's Water Monitor.
Contents |
Description
The Water monitor, (Varanus salvator) is a large species of monitor lizard capable of growing to 3.21 metres (10.5 ft) in length, with the average size of most adults at 1.5 metres (4.9 ft) long.[1] Maximum weight of Varanus salvator can be over 25 kilograms (55 lb), but most are half that size. Their body is muscular with a long, powerful, laterally compressed tail. Water monitors are one of the most common monitor lizards found throughout Asia, and range from Sri Lanka, India, Indochina, the Malay Peninsula and various islands of Indonesia, living in areas close to water.
Etymology
The generic name Varanus is derived from the Arabic waral (ورل), which translates as "monitor" in English. The specific name is the Latin word for "Saviour" denoting a possible religious connotation.[2] The Water monitor is occasionally confused with the Crocodile monitor (V. salvadorii) because of their similar scientific names.[3]
In Thailand, the word water monitor or actually local word 'เหี้ย' (hia) is used as an insulting word for bad and evil things including a bad person. Its name is also considered a word bringing a bad luck, so some people prefer to call them 'ตัวเงินตัวทอง' which means 'silver and gold' in Thai to avoid the jinx.
The origin of this offensive meaning can be traced back to a time when more people lived in rural areas in close proximity to monitor lizards. Traditionally, Thai villagers lived in 2-story houses, the top floor was for living while the ground floor was designed to be a space for domestic animals such as pigs, chickens, and dogs. Water monitors would enter the ground floor and eat or maim the domestic animals, also hence the other name 'ตัวกินไก่' (Tua kin kai - chicken eater).
In Indonesian and Malay, the water monitor is called 'biawak'.
Subspecies of Varanus salvator
- Asian Water Monitor, Varanus salvator salvator the nominotypic subspecies is now restricted to Sri Lanka where it is known as the Kabaragoya in Sinhala, and Udumbu in Tamil.
- Andaman Islands Water Monitor, Varanus salvator andamanensis: Andaman Islands; Type locality: Port Blair, Andaman Islands.
- Two-striped Water Monitor, Varanus salvator bivittatus: Java, Bali, Lombok, Sumbawa, Flores, Ombai (Alor), Wetar and some neighbouring islands within the Sunda arch, Indonesia; Type locality: Java (designated by Mertens 1959).
- Black Water Monitor, Varanus salvator komaini: Thailand. Type locality: Amphoe La-ngu, Satun Prov., Thailand, and Thai-Malaysian border area. This was formerly a subspecies, but now regarded as a synonym of V. s. macromaculatus.[4]
- Southeast Asian Water Monitor, Varanus salvator macromaculatus: Type locality: Siam (Thailand). Mainland Southeast Asia, Singapore, Sumatra, Borneo and smaller associated offshore islands.[4]
- Yellow-headed Water Monitor was deemed a race until 2007 when it was elevated to full species.[4][5]
Behavior and diet
Water monitors can be defensive, using their tail, claws, and jaws when fighting. They are excellent swimmers, using the raised fin located on their tails to steer through water. Water Monitors are carnivores, and have a wide range of foods. They are known to eat fish, frogs, rodents, birds, crabs, and snakes.[2] They have also been known to eat turtles, as well as young crocodiles and crocodile eggs[6] Like the Komodo Dragon, they will often eat carrion.[2]
Conservation
In Hong Kong, it is a protected species under Wild Animals Protection Ordinance Cap 170. In Malaysia, this species is one of the most common wild animals around with numbers comparable to that of the population of macaques there. Although many fall prey to humans via road kill and animal cruelty, it still thrives in most states of Malaysia especially in the shrubs of the east-coast states such as Pahang and Terengganu. Malay "kampung" boys and young working class Malay men often catch and kill water monitors for their own amusement although the widespread population of the species causes the lack of conservation attention. In the east-coast states of Malaysia, this species is very common in roadkill. In Thailand, all monitor lizards are protected species.[7]
Gallery
References
- ^ Pianka, King & king. Varanoid lizards of the world. 2004
- ^ a b c Robert George Sprackland (1992). Giant lizards. Neptune, NJ: T.F.H. Publications. ISBN 0-86622-634-6.
- ^ Netherton, John; Badger, David P. (2002). Lizards: A Natural History of Some Uncommon Creatures--Extraordinary Chameleons, Iguanas, Geckos, and More. Stillwater, MN: Voyageur Press. pp. 140–141. ISBN 0-7603-2579-0.
- ^ a b c Koch, A., M. Auliya, A. Schmitz, U. Kuch & W. Böhme. (2007). Morphological Studies on the Systematics of South East Asian Water Monitors (Varanus salvator Complex): Nominotypic Populations and Taxonomic Overview. pp. 109-180. In Horn, H.-G., W. Böhme & U. Krebs (eds.), Advances in Monitor Research III. Mertensiella 16, Rheinbach.
- ^ monitor-lizards.net. "Soterosaurus: Mindanao Water Monitor". http://www.monitor-lizards.net/species/soterosaurus/cumingi.html. Retrieved 20 March 2012.
- ^ Whitaker, Rom (1981) Bangladesh - Monitors and turtles Hamadryad. 6 (3): 7-9
- ^ "Species Diversity, Distribution and Proposed Status of Monitor Lizards (Family Varanidae) in Southern Thailand". The Natural History Journal of Chulalongkorn University (Chulalongkorn University) 1 (1): 39–46. 2001-08. http://www2.biology.sc.chula.ac.th/web%20of%20NHJCU%20PDF/1-1,%2039-46.pdf. Retrieved 2009-06-28.
- Bennett, Daniel 1995 The water monitor Varanus salvator Reptilian 3 (8): 15-21
- Das, Indraneil 1988 New evidence of the occurrence of water monitor (Varanus salvator) in Meghalaya J. Bombay Nat. Hist. Soc. 86: 253-255
- Deraniyagala, P. E. P. 1944 Four New Races of the Kabaragoya Lizard Varanus salvator. Spolia Zeylanica 24: 59-62
- Pandav, Bivash 1993 A preliminary survey of the water monitor (Varanus salvator) in Bhitarkanika Wildlife Sanctuary, Orissa Hamadryad 18: 49-51
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