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Bengal monitor: Difference between revisions
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Bengal monitors have external nostril openings (nares) that is slit-like and oriented near horizontal, and positions between the eye and the tip of the snout. The nares can be closed at will, especially to keep away debris or water.<ref>Auffenberg (1994):22</ref> The scales of the skin are rougher in patches and on the sides, they have minute pits, especially well distributed in males.<ref>Auffenberg (1994):36</ref> These scales with micropores have glandular structures in the underlying dermal tissue and produce a secretion which may be a pheromone-like substance. Like other monitors, Bengal monitors have a forked tongue similar to snakes. The function is mainly sensory, and is not very involved in the transport of food down the throat. Bengal monitors have fat deposits in the tail and body that serve them in conditions when prey are not easily available. | Bengal monitors have external nostril openings (nares) that is slit-like and oriented near horizontal, and positions between the eye and the tip of the snout. The nares can be closed at will, especially to keep away debris or water.<ref>Auffenberg (1994):22</ref> The scales of the skin are rougher in patches and on the sides, they have minute pits, especially well distributed in males.<ref>Auffenberg (1994):36</ref> These scales with micropores have glandular structures in the underlying dermal tissue and produce a secretion which may be a pheromone-like substance. Like other monitors, Bengal monitors have a forked tongue similar to snakes. The function is mainly sensory, and is not very involved in the transport of food down the throat. Bengal monitors have fat deposits in the tail and body that serve them in conditions when prey are not easily available. | ||
The lungs have spongy tissue unlike the sacs of other [[ | The lungs have spongy tissue unlike the sacs of other [[sauria]]ns. This allows for a greater rate of gas exchange and allows a faster metabolic rate and higher activity levels. Like all monitors, they have subpleurodont teeth, meaning the teeth are fused to the inside of the jaw bones.<ref>Auffenberg (1994):50</ref> The teeth are placed one behind another, and there are replacement teeth behind and between each functional tooth (polyphyodont). The maxillary and dentary teeth are laterally compressed, sometimes with a slightly serrate cutting edge, while the premaxillary teeth are conical. There are 78 premaxillary teeth, 10 maxillary and 13 dentary teeth. Replacement teeth move forward and about four replacements happens each year for a tooth.<ref>Auffenberg (1994):51</ref> While monitor lizards are venomous, there are no reports of the effects of venom in Bengal monitors other than a very controversial case report of fatal renal failure as a result of envenomation from this species.<ref>{{Cite journal|last=White|first=Julian|last2=Weinstein|first2=Scott A.|date=2015-04-21|title=Reply to Vikrant and Verma about "Monitor Lizard Envenoming"|url=http://www.tandfonline.com/doi/full/10.3109/0886022X.2015.1006116|journal=Renal Failure|language=en|volume=37|issue=4|pages=740–741|doi=10.3109/0886022X.2015.1006116|issn=0886-022X}}</ref> | ||
== Distribution and habitat == | == Distribution and habitat == | ||
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The species ranges from Iran to Java, among the most widely distributed of monitor lizards as they are eurytopic and adaptable to a range of habitats.<ref name=":0" /> It is found in river valleys in eastern [[Iran]], [[Afghanistan]], [[India]], [[Nepal]], [[Sri Lanka]], [[Pakistan]], [[Bangladesh]] and [[Burma]]. The closely related species, the [[clouded monitor]], occurs in southern [[Burma]], [[Vietnam]], [[Cambodia]], [[Thailand]], [[Malaysia]], [[Sumatra]], [[Java]] and the [[Sunda Islands]]. They have not been confirmed on Sumatra, and have been found to be absent from the [[Andaman Islands]].<ref>Auffenberg (1994):86</ref> | The species ranges from Iran to Java, among the most widely distributed of monitor lizards as they are eurytopic and adaptable to a range of habitats.<ref name=":0" /> It is found in river valleys in eastern [[Iran]], [[Afghanistan]], [[India]], [[Nepal]], [[Sri Lanka]], [[Pakistan]], [[Bangladesh]] and [[Burma]]. The closely related species, the [[clouded monitor]], occurs in southern [[Burma]], [[Vietnam]], [[Cambodia]], [[Thailand]], [[Malaysia]], [[Sumatra]], [[Java]] and the [[Sunda Islands]]. They have not been confirmed on Sumatra, and have been found to be absent from the [[Andaman Islands]].<ref>Auffenberg (1994):86</ref> | ||
The species is mainly distributed through lower elevations below an altitude of 1500 metres, and is found both in dry semiarid desert habitats to moist forest. They are often found in agricultural areas.<ref>Auffenberg (1994):103-118</ref | The species is mainly distributed through lower elevations below an altitude of 1500 metres, and is found both in dry semiarid desert habitats to moist forest. They are often found in agricultural areas.<ref name="iucn" /><ref>Auffenberg (1994):103-118</ref> | ||
== Ecology and behaviour == | == Ecology and behaviour == | ||
Bengal monitors are usually solitary and usually found on the ground, although the young are often seen on trees. Clouded monitors by contrast have a greater propensity for tree climbing. Bengal and [[yellow monitor | Bengal monitors are usually solitary and usually found on the ground, although the young are often seen on trees. Clouded monitors by contrast have a greater propensity for tree climbing. Bengal and [[yellow monitor]]s are sympatric but are partially separated by their habitat as Bengal monitors prefers forest over agricultural areas.<ref name="herpconbio.org">Ghimire, H. R., & Shah, K. B. (2014). Status and habitat ecology of the Yellow Monitor, Varanus flavescens, in the Southeastern part of Kanchanpur District, Nepal. Herpetological Conservation and Biology, 9(2), 387-393. http://www.herpconbio.org/Volume_9/Issue_2/Ghimire_Shah_2014.pdf</ref> Bengal monitors shelter in burrows they dig or crevices in rocks and buildings, whilst clouded monitors prefer tree hollows. Both species will make use of abandoned termite mounds. Bengal monitors are [[Diurnality|diurnal]] like other monitors, becoming active around 6 AM and bask in the morning sun.<ref>Auffenberg (1994):138-145</ref> During winter in the colder parts of their range, they may take shelter and go through a period of reduced metabolic activity.<ref>Auffenberg (1994):147</ref> They are not territorial, and may change their range seasonally in response to food availability.<ref>Auffenberg (1994):175</ref> | ||
They are usually shy and avoid humans. They have keen eyesight and can detect human movement nearly 250 m away. When caught, a few individuals may bite, but rarely do so.<ref>Auffenberg (1994):182</ref> | They are usually shy and avoid humans. They have keen eyesight and can detect human movement nearly 250 m away. When caught, a few individuals may bite, but rarely do so.<ref>Auffenberg (1994):182</ref> | ||