Monitor lizard

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Monitor lizards
An Australian lace monitor(Varanus varius) on a tree.
An Australian lace monitor
(Varanus varius) on a tree.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Order: Squamata
Suborder: Scleroglossa
Infraorder: Anguimorpha
Family: Varanidae
Genus: Varanus
Merrem, 1820
Species

Category:Monitor lizards

Monitor lizards are the family Varanidae, a group of carnivorous lizards which includes the largest living lizard, the Komodo dragon. Varanidae is monotypic, containing only the genus Varanus.

In Tamil and Malayalam monitor lizards are known as "Udumbu" and in Australia they are known as goannas (See main article). In Kannada monitor lizards are known as "Uda". In Sinhalese the monitor lizard is known as "Kabaragoya".

Contents

[edit] Distribution

The various species of Varanus cover a vast area, occurring through Africa, the Asian subcontinent from India and Sri Lanka to China, down Southeast Asia to Indonesia, the Philippines, New Guinea, Australia and islands of the Indian Ocean and South China Sea.

[edit] Evolutionary overview

Monitor lizards differ greatly from other lizards in several ways, possessing a relatively high metabolic rate for reptiles and several sensory adaptations that benefit the hunting of live prey. Recent research indicates that the varanid lizards, including the Komodo dragon, may have very weak venom.[1] The discovery of venom in Monitor Lizards, as well as in agamid Lizards, led to the Toxicofera hypothesis: that all venomous reptiles share a common venomous ancestor. Some monitor lizards are apparently capable of parthenogenesis.[2] Almost all Monitor lizards are carnivorous.

[edit] Origin of the name

The genus name, "Varanus" is derived from the Arabic word waral ورل, which is translated to English as "monitor". It has been suggested that the occasional habit of varanids to stand on their two hind legs and to appear to "monitor" their surroundings led to the original Arabic name.[3] According to legend, these lizards were supposed to warn people that crocodiles were nearby.[4]

[edit] Intelligence

Varanid lizards are very intelligent, and some species can even count.[5] Careful studies feeding V. albigularis at the San Diego Zoo varying numbers of snails showed that they can distinguish numbers up to six.[5][4][6] V. niloticus have been observed to cooperate when foraging.[7] One varanid lures the female crocodile away from her nest while the other opens the nest to feed on the eggs.[7] The decoy then returns to also feed on the eggs.[7][4] Komodo dragons, V. komodoensis, at the Smithsonian National Zoological Park in Washington, D.C., recognize their keepers and seem to have distinct personalities.[4]

[edit] Monitor lizards as pets

Monitor lizards have become a staple in the reptile pet trade. The most commonly kept monitors are the savannah monitor, white throated monitor, and Acklin's monitor, due to their relatively small size and ease of domestication. Nile monitors, water monitors, mangrove monitors, and papau monitors have also been kept in captivity. Like all reptiles that are kept as pets, monitors need hiding places, and an appropriate substrate (bedding). Monitors also need a large water dish in which they can soak their entire body. In the wild, monitors will eat anything they can overpower, but crickets, superworms, and the occasional rodent make up most of the captive monitors' diet. Boiled eggs, silkworms, earthworms, and feeder fish can also be fed to monitors. Monitor lizards have been compared to reptilian cats - independent animals with different personalities. However, due to their predatory nature and large size some monitors can be dangerous to keep as pets. Adult nile monitors can reach seven feet in length, and are stronger than an alligator of equal weight.

[edit] The Bengal Monitor Lizards

The Bengal Monitor lizard, also known as the Common Indian Monitor lizard, is not uncommon in Asia and Africa. It is widely said to have been used to scale the fort of Kondana in Pune, India, by Tanaji Malusare, a general in the army of the Maratha ruler Shivaji. The skin of this lizard has traditionally been utilized in making the Kanjira, a South Indian classical percussion instrument. Now however, it is not in vogue owing to the increased awareness to the dwindling population of the lizard. The lizard evokes mixed responses from the people across the world. It is considered a delicacy in Sri Lanka. It is killed for sport in North Eastern India. It is revered in Maharashtra, India where an entire clan of people use "Ghorpade" as their surname after "Ghorpad", the local name for the Bengal Monitor lizard [8].

[edit] Extinct giants

During the Pleistocene giant monitor lizards lived in Southeast Asia and Australiasia, the best known being Megalania prisca. Recently reclassified as a constituent of the genus Varanus, it is an iconic member of the Pleistocene megafauna of Australia.

[edit] Classification

A Nile monitor
A Nile monitor
A monitor lizard seen at the Australia Zoo.
A monitor lizard seen at the Australia Zoo.

Genus Varanus

Emerald tree monitor (also called Green tree monitor) lizard Varanus prasinus
Emerald tree monitor (also called Green tree monitor) lizard Varanus prasinus
Asian water monitor (Varanus salvator salvator).
Asian water monitor (Varanus salvator salvator).
  • Water Monitor, Varanus salvator
    • Asian Water Monitor, Varanus salvator salvator
    • Andaman Islands Water Monitor, Varanus salvator andamanensis
    • Two-striped Water Monitor, Varanus salvator bivittatus
    • Cuming's Water Monitor, Varanus salvator cumingi
    • Black Water Monitor, Varanus salvator komaini
    • Marbled Water Monitor, Varanus salvator marmoratus
    • Negros Water Monitor, Varanus salvator nuchalis
    • Togian Water Monitor, Varanus salvator togianus
  • Spotted Tree Goanna, Varanus scalaris
  • Mangrove pygmy goanna, Varanus semiremex
  • Spencer's Goanna, Varanus spenceri
  • St. Isabel Mangrove Monitor, Varanus spinulosus
  • Storr's Goanna, Varanus storri
    • Eastern Storr's Goanna, Varanus storri storri
    • Western Storr's Monitor, Varanus storri ocreatus
  • Rossel Island Tree Monitor, Varanus telenesetes
  • Timor Tree Monitor, Varanus timorensis
  • Black-headed Monitor, Varanus tristis
    • Freckled Monitor, Varanus tristis orientalis
  • Lace Monitor, Varanus varius
  • Yemen Monitor, Varanus yemenensis
  • Tri-colored Monitor, Varanus yuwonoi
  • Varanus zugorum

[edit] References

  1. ^ Fry, B.G; Vidal, N; Norman J.A.; Vonk F.J.; Scheib, H.; Ramjan S.F.R; Kuruppu S.; Fung, K.; Hedges, B.; Richardson M.K.; Hodgson, W.C.; Ignjatovic, V.; Summerhays, R. and Kochva, E. 2006. Early evolution of the venom system in lizards and snakes. Nature. 439, 584-588. Summary
  2. ^ Smith, Kerri. Dragon virgin births startle zoo keepers. Nature. Retrieved on 2006-12-20.
  3. ^ Pianka, E.R.; King, D.R. and King, R.A. 2004. Varanoid Lizards of the World. Indiana University Press.
  4. ^ a b c d Pianka, Eric R. Varinidae [1]
  5. ^ a b King, Dennis & Green, Brian. 1999. Goannas: The Biology of Varanid Lizards. University of New South Wales Press. ISBN 0-86840-456-X, p. 43.
  6. ^ The Weekend Australian. July 24-25, 1999, p. 12.
  7. ^ a b c King, Dennis & Green, Brian. 1999. Goannas: The Biology of Varanid Lizards. University of New South Wales Press. ISBN 0-86840-456-X, p. 43.
  8. ^ Little Book of Monitor Lizards, Daniel Bennett, Viper Press, 1995

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