Reptiles
Crocodile Monitor
Varanus salvadorii · also called Salvadori's monitor, Papuan monitor, artellia
Somewhere in the rainforest canopy of New Guinea moves a lizard that can stretch two and a half metres from nose to tail tip, most of it a long, thin, whip-like tail. The crocodile monitor is usually called the longest lizard in the world, and it is one of the least studied of all the big monitors.
Overview
Varanus salvadorii is a large, slender, strongly arboreal monitor endemic to the lowland rainforest and swamp forest of New Guinea. Verified animals reach about 2.5 m, with old reports of much longer ones, and roughly two thirds of that is tail. It has a distinctive blunt, rounded snout, long limbs, curved claws, and serrated, backward-hooked teeth. It hunts birds, eggs, bats, small mammals, and reptiles through the canopy and along rivers.
Longest, not largest
Because so much of its length is a thin tail, the crocodile monitor is usually ranked the longest living lizard, while the shorter but far heavier Komodo dragon is the biggest and most massive. The long tail is a permanent tool for balance in the trees, for steering, and as a whip that a cornered monitor swings hard enough to hurt.
Barely known
It lives in remote, dense forest, is shy, and has never had the field study its relatives have received, so much of its natural history is uncertain. Local peoples hunt it for drum-head skin and meat, and it is exported for the exotic pet trade with a reputation as a demanding and risky animal to keep.
Status
The crocodile monitor is listed as Least Concern on the basis of a wide range and no clear evidence of decline, but data are poor, and hunting, the pet trade, and the loss of New Guinea lowland rainforest are all recognised pressures.
Crocodile Monitor: common questions
Is the crocodile monitor really the longest lizard in the world?
It is usually given that title, with an important qualification. Reliably measured crocodile monitors reach around 2.5 m, and there are older, less certain reports of animals between 3.5 and 4.75 m, which if accurate would make it the longest living lizard. The catch is that roughly two thirds of that length is an extremely long, thin tail, so by body length or by weight the Komodo dragon, which is shorter overall but vastly heavier and bulkier, is the larger animal. So the fairest statement is that the crocodile monitor is probably the longest lizard, and the Komodo dragon is the biggest and heaviest.
Why is it called a crocodile monitor?
The name refers to its appearance and size rather than any close relationship to crocodiles, which are not lizards at all. Several features suggested the comparison to early naturalists and to the people who live alongside it, among them its great length, its rows of large, raised, dark scales, its blunt, deep, rounded snout unlike the pointed face of most monitors, and its long, powerful, laterally flattened tail. Its scientific name, Varanus salvadorii, honours the Italian zoologist Tommaso Salvadori, and it is also known as Salvadori's monitor and the Papuan monitor.
How dangerous is a crocodile monitor?
To a person who leaves it alone in the forest, not very, since it is shy and will climb or flee. To a keeper or anyone who handles or corners one, it is among the more hazardous monitors. It is fast, strong, and agile, with long claws that rake, a hard bite from jaws lined with sharp, serrated, backward-hooked teeth that tear rather than crush, and a long tail that it lashes like a whip. Bites can cause deep wounds and, as with other large monitors, may become infected. Reports of the species killing large domestic animals or people exist in New Guinea folklore but are not well substantiated, and much of the fear attached to it is cultural rather than documented.
How well is the crocodile monitor known and protected?
Poorly on both counts, compared with its famous relatives. It lives in some of the least accessible rainforest in the world, is secretive and largely arboreal, and has never been the subject of the sustained field study that the Komodo dragon and the Nile and water monitors have received, so basic facts about its numbers, range limits, diet, and breeding in the wild remain uncertain. It is listed by the IUCN as Least Concern, mainly because there is no evidence of a sharp decline across its large range, and international trade is regulated under CITES, but the steady clearance of New Guinea lowland forest for logging and agriculture is reducing its habitat.