Varanus salvadorii
Encyclopedia
Varanus salvadorii is a monitor lizard
found in New Guinea
. It is also known by the common names Salvadori's monitor, Crocodile monitor, Papua(n) monitor, and Artellia. The largest monitor lizard in New Guinea, it is believed to be one of the longest lizards in the world, reaching up to 244 cm (8 ft). It is the sole member of the subgenus
Papusaurus. V. salvadorii is an arboreal lizard
with a dark green body and yellowish bands, a blunt snout and a very long tail. It lives in mangrove swamps and coastal rain forests in the southeastern part of the island, where it feeds on bird
s, small mammal
s, eggs, and carrion in the wild, using teeth that are better adapted than those of most monitors for seizing fast-moving prey. Like all monitors it has anatomical features that enable it to breathe more easily when running than other lizards can, and V. salvadorii is thought to have greater stamina than most monitors. Little is known about its reproduction and development, as the species is very difficult to breed in captivity
.
V. salvadorii is threatened by deforestation
and poaching
, and is protected by the CITES agreement. The lizard is hunted and skinned alive by tribesmen to make drums, who describe the monitor as an evil spirit that "climbs trees, walks upright, breathes fire, and kills men"; yet the tribesman maintain that the monitor gives warnings if there are crocodile
s nearby.
The generic
name Varanus is derived from the Arabic waral (ورل), meaning "Lizard". The term "Monitor" is thought to have come about from confusion between waral and the German warnen, meaning "warning". The term "Goanna" came about as a corruption of the name "Iguana". The specific
name is derived from a Latinization of Tommaso Salvadori
, an Italian ornithologist who worked in New Guinea
. Later, in 1885, it was renamed Varanus salvadorii by George Albert Boulenger
. The Papua monitor is occasionally confused for the Water monitor
(V. salvator) because of their similar scientific names.
about 40 million years ago and migrated to Australia
. Around 15 million years ago, a collision between Australia and Southeast Asia
allowed the varanids to move into what is now the Indonesian archipelago.
V. salvadorii has been placed cladistically
as part of a species cluster with the Lace monitor
(V. varius) and the Komodo dragon
(V. komodoensis). This study was based upon mitochondrial DNA
and microcomplement fixation analysis. A theory has been put forth that the species diverged from a common ancestor, as the Torres Strait
separating New Guinea from Australia
is less than 90 km (55.9 mi) long, a distance that could have been covered fairly easily with island hopping. However, the similarities between V. salvadorii and V. varius may simply be an example of convergent evolution
. Another clade postulated by Eric Pianka
places V. salvadorii in a larger "Australian" clade of large monitors, along with other species as the Komodo dragon, the Lace monitor, the Perentie
(V. giganteus), the Argus monitor
(V. panoptes), and the Sand goanna
(V. gouldii).
, V. salvadorii occurs in both the state Papua New Guinea
and the Indonesia
n region of West Papua. It inhabits the high and low canopies of the lowland rainforests and coastal mangrove
swamps, sometimes venturing out of these areas during floods in the rainy seasons. No detailed field investigation data is available for V. salvadorii, so the full extent of its range is unknown. Its remote and generally inaccessible habitat is the main factor in preventing detailed study of this animal in its natural habitat
.
. The body of the lizard is dark green with rings of yellow spots. The tail is banded yellow and black. It has long straight teeth and prominent curved claws. There is no external sexual dimorphism
.
Unique among living varanid species, the animal's tail is two-thirds longer than the snout-to-vent length in both juveniles and adults. Herpetologist Robert Sprackland gives the proportion as the tail being 210% of the animal's body length. At birth V. salvadorii is about 45 cm (17.7 in) long, while a sexually mature female may grow to 150 cm (4.9 ft). The longest recorded specimen is 244 cm (8 ft) in length, but it has been speculated that it may grow longer.
Varanus salvadorii has what physiologists refer to as mammal-like aerobic abilities; this is accomplished by means of a positive pressure gular pump
in the animal’s throat to assist lung ventilation. The majority of lizards cannot run and breathe at the same time due to Carrier's constraint
, but monitor lizards are exceptions to this rule. The development of this ventilatory pump is analogous to the evolution of the diaphragm in mammals, which ventilates the lung independently of locomotion; scientists place Varanus salvadorii as the species with the highest endurance in this regard. This would suggest that the lizard is at an evolutionary midpoint, relying on both forms of breathing.
V. salvadorii is an arboreal lizard. As such, it can hang onto branches with its rear legs and occasionally use its tail as a prehensile grip. The primary use of the tail, however, is to counterbalance its weight when leaping from one branch to another. The tail may also be used for defense, as captive specimens have attempted to whip their keepers with their tails. This species is occasionally seen in the pet trade, but has earned a reputation of being aggressive and unpredictable. Although they are known to rest and bask in trees, they sleep on the ground or submerged in water.
The monitors will rise up on their hind legs to check their surroundings, a behavior that has also been documented in Gould's monitor
s (V. gouldii). According to native belief, they will give a warning call if they see crocodile
s. In general V. salvadorii avoids human contact, but their bites are capable of causing infection, like the Komodo dragon's. One fatality is reported from a bite in 1983 when a Papuan woman was bitten and later died from an infection.
, small animals, and carrion
. There are reports from natives that it may take down pigs, deer
, and hunting dogs, and that the monitor hauls its prey into the canopy to consume it. Its only competition is the New Guinea Singing Dog
. Captive specimens have been known to eat fish
, frog
s, rodent
s, chickens, and dog food.
V. salvadorii has been observed hunting prey in a unique fashion for monitor lizards. Rather than following its prey to ambush it from behind, V. salvadorii will stalk its prey and anticipate where it will run meeting it headlong.
. It faces threats from deforestation and poaching as it is hunted and skinned alive by native peoples to make drums, who consider the monitor an evil spirit that "climbs trees, walks upright, breathes fire, and kills men". The species is maintained at 17 zoological parks worldwide. The total U.S. captive zoo population totals 52 individuals and an unknown number in private collections.
Monitor lizard
Monitor lizards are usually large reptiles, although some can be as small as in length. They have long necks, powerful tails and claws, and well-developed limbs. Most species are terrestrial, but arboreal and semiaquatic monitors are also known...
found in New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
. It is also known by the common names Salvadori's monitor, Crocodile monitor, Papua(n) monitor, and Artellia. The largest monitor lizard in New Guinea, it is believed to be one of the longest lizards in the world, reaching up to 244 cm (8 ft). It is the sole member of the subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
Papusaurus. V. salvadorii is an arboreal lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
with a dark green body and yellowish bands, a blunt snout and a very long tail. It lives in mangrove swamps and coastal rain forests in the southeastern part of the island, where it feeds on bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, small mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, eggs, and carrion in the wild, using teeth that are better adapted than those of most monitors for seizing fast-moving prey. Like all monitors it has anatomical features that enable it to breathe more easily when running than other lizards can, and V. salvadorii is thought to have greater stamina than most monitors. Little is known about its reproduction and development, as the species is very difficult to breed in captivity
Captivity (animal)
Animals that live under human care are in captivity. Captivity can be used as a generalizing term to describe the keeping of either domesticated animals or wild animals. This may include for example farms, private homes and zoos...
.
V. salvadorii is threatened by deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
and poaching
Poaching
Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...
, and is protected by the CITES agreement. The lizard is hunted and skinned alive by tribesmen to make drums, who describe the monitor as an evil spirit that "climbs trees, walks upright, breathes fire, and kills men"; yet the tribesman maintain that the monitor gives warnings if there are crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s nearby.
Taxonomy and etymology
V. salvadorii was first described as Monitor salvadorii by Wilhelm Peters and Giacomo Doria in 1878 from a female specimen with a snout-to-vent length of 48 cm (18.9 in) long and a tail measuring 114 cm (44.9 in) in length.The generic
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
name Varanus is derived from the Arabic waral (ورل), meaning "Lizard". The term "Monitor" is thought to have come about from confusion between waral and the German warnen, meaning "warning". The term "Goanna" came about as a corruption of the name "Iguana". The specific
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
name is derived from a Latinization of Tommaso Salvadori
Tommaso Salvadori
Count Adelardo Tommaso Salvadori Paleotti was an Italian zoologist and ornithologist.Salvadori was born in Porto San Giorgio, son of Count Luigi Salvadori and Ethel. He took an early interest in birds and published a catalogue of the birds of Sardinia in 1862...
, an Italian ornithologist who worked in New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
. Later, in 1885, it was renamed Varanus salvadorii by George Albert Boulenger
George Albert Boulenger
George Albert Boulenger FRS was a Belgian-British zoologist who identified over 2000 new animal species, chiefly fish, reptiles and amphibians.-Life:...
. The Papua monitor is occasionally confused for the Water monitor
Water monitor
The Water monitor, is a large species of monitor lizard capable of growing to in length, with the average size of most adults at long. Maximum weight of Varanus salvator can be over , but most are half that size. Their body is muscular with a long, powerful, laterally compressed tail...
(V. salvator) because of their similar scientific names.
Evolutionary development
The evolutionary development of V. salvadorii started with the Varanus genus, which originated in AsiaAsia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
about 40 million years ago and migrated to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. Around 15 million years ago, a collision between Australia and Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
allowed the varanids to move into what is now the Indonesian archipelago.
V. salvadorii has been placed cladistically
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
as part of a species cluster with the Lace monitor
Lace monitor
The Lace Monitor, or Lace Goanna, Varanus varius, is a member of the monitor lizard family, Australian members of which are commonly known as goannas. It belongs to the subgenus Varanus....
(V. varius) and the Komodo dragon
Komodo dragon
The Komodo dragon , also known as the Komodo monitor, is a large species of lizard found in the Indonesian islands of Komodo, Rinca, Flores, Gili Motang and Gili Dasami. A member of the monitor lizard family , it is the largest living species of lizard, growing to a maximum length of in rare cases...
(V. komodoensis). This study was based upon mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
and microcomplement fixation analysis. A theory has been put forth that the species diverged from a common ancestor, as the Torres Strait
Torres Strait
The Torres Strait is a body of water which lies between Australia and the Melanesian island of New Guinea. It is approximately wide at its narrowest extent. To the south is Cape York Peninsula, the northernmost continental extremity of the Australian state of Queensland...
separating New Guinea from Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
is less than 90 km (55.9 mi) long, a distance that could have been covered fairly easily with island hopping. However, the similarities between V. salvadorii and V. varius may simply be an example of convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
. Another clade postulated by Eric Pianka
Eric Pianka
Eric Rodger Pianka is an American biologist, whose work includes herpetology and evolutionary ecology. His textbook, Evolutionary Ecology is considered a classic, and his writings for the general public and television appearances have made him an influential figure.-Youth:Pianka was born in...
places V. salvadorii in a larger "Australian" clade of large monitors, along with other species as the Komodo dragon, the Lace monitor, the Perentie
Perentie
The Perentie is the largest monitor lizard or goanna native to Australia, and fourth largest lizard on earth, after the Komodo Dragon, crocodile monitor and the water monitor...
(V. giganteus), the Argus monitor
Argus monitor
The Argus monitor is a monitor lizard found in northern regions of Australia and southern New Guinea. It is also commonly known as the Yellow-spotted Monitor....
(V. panoptes), and the Sand goanna
Sand goanna
The Sand goanna is a large Australian monitor lizard - also known as Gould's monitor, the Sand monitor, or Racehorse goanna....
(V. gouldii).
Distribution
The largest of the seven species of monitors found on the island of New GuineaNew Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
, V. salvadorii occurs in both the state Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...
and the Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
n region of West Papua. It inhabits the high and low canopies of the lowland rainforests and coastal mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
swamps, sometimes venturing out of these areas during floods in the rainy seasons. No detailed field investigation data is available for V. salvadorii, so the full extent of its range is unknown. Its remote and generally inaccessible habitat is the main factor in preventing detailed study of this animal in its natural habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
.
Biology and morphology
The most characteristic feature of this monitor is its blunt bulbous snout, which makes this species look different than every other monitor on New Guinea and lends to its common name of tree crocodileCrocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
. The body of the lizard is dark green with rings of yellow spots. The tail is banded yellow and black. It has long straight teeth and prominent curved claws. There is no external sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
.
Unique among living varanid species, the animal's tail is two-thirds longer than the snout-to-vent length in both juveniles and adults. Herpetologist Robert Sprackland gives the proportion as the tail being 210% of the animal's body length. At birth V. salvadorii is about 45 cm (17.7 in) long, while a sexually mature female may grow to 150 cm (4.9 ft). The longest recorded specimen is 244 cm (8 ft) in length, but it has been speculated that it may grow longer.
Varanus salvadorii has what physiologists refer to as mammal-like aerobic abilities; this is accomplished by means of a positive pressure gular pump
Buccal pumping
Buccal pumping is a method of respiration in which the animal moves the floor of the mouth in a rhythmic manner that is externally apparent.This method has several stages. These will be described for an animal starting with lungs in a deflated state: First, the glottis is closed, and the...
in the animal’s throat to assist lung ventilation. The majority of lizards cannot run and breathe at the same time due to Carrier's constraint
Carrier's constraint
Carrier's constraint is the observation that air-breathing vertebrates which have two lungs and flex their bodies sideways during locomotion find it very difficult to move and breathe at the same time, because:...
, but monitor lizards are exceptions to this rule. The development of this ventilatory pump is analogous to the evolution of the diaphragm in mammals, which ventilates the lung independently of locomotion; scientists place Varanus salvadorii as the species with the highest endurance in this regard. This would suggest that the lizard is at an evolutionary midpoint, relying on both forms of breathing.
Behavior
The monitors will rise up on their hind legs to check their surroundings, a behavior that has also been documented in Gould's monitor
Sand goanna
The Sand goanna is a large Australian monitor lizard - also known as Gould's monitor, the Sand monitor, or Racehorse goanna....
s (V. gouldii). According to native belief, they will give a warning call if they see crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s. In general V. salvadorii avoids human contact, but their bites are capable of causing infection, like the Komodo dragon's. One fatality is reported from a bite in 1983 when a Papuan woman was bitten and later died from an infection.
Diet
The teeth of V. salvadorii do not resemble the teeth of other monitor species, which are typically blunt, peglike and face slightly rearward. V. salvadoriis upper teeth are long and fanglike standing vertical from the jawbone, designed to hook into fast-moving or feathered prey such as birds, bats, and rodents. Its lower teeth are housed in a fleshy sheath. In the wild it is the top predator in New Guinea, feeding on birds, eggsEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
, small animals, and carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. There are reports from natives that it may take down pigs, deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
, and hunting dogs, and that the monitor hauls its prey into the canopy to consume it. Its only competition is the New Guinea Singing Dog
New Guinea Singing Dog
The New Guinea Singing Dog is a wild dog once found throughout New Guinea. New Guinea Singing Dogs are named for their unique howl....
. Captive specimens have been known to eat fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s, rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, chickens, and dog food.
V. salvadorii has been observed hunting prey in a unique fashion for monitor lizards. Rather than following its prey to ambush it from behind, V. salvadorii will stalk its prey and anticipate where it will run meeting it headlong.
Reproduction
Reproduction has only been observed in captivity, so nothing is known about its reproduction in the wild. The egg clutches, comprising four to twelve eggs, are deposited around October to January, with the eggs showing a remarkable difference in dimensions, a phenomenon for which no explanation is known. Dimensions may vary from 7.5x3.4 cm (3.0x1.3 in) to 10x4.5 cm (3.9x1.8 in), while weight may vary from 43.3 to 60.8 grams (1.53 to 2.14 oz). Most clutches laid in captivity have been infertile, and there have only been four successful breedings documented thus far. Hatchlings are about 18 inches (45 cm) long and weigh around 56 grams (2.0 oz). Like that of many other monitors, the hatchlings of V. salvadorii are more colorful than adults and feed primarily on insects and small reptiles.Conservation status
V. salvadorii is currently protected under the Convention on International Trade of Endangered Species (CITES) Appendix II, which requires an exportation permit for international trade. It is not listed on the IUCN Red List or the Endangered Species ActEndangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
. It faces threats from deforestation and poaching as it is hunted and skinned alive by native peoples to make drums, who consider the monitor an evil spirit that "climbs trees, walks upright, breathes fire, and kills men". The species is maintained at 17 zoological parks worldwide. The total U.S. captive zoo population totals 52 individuals and an unknown number in private collections.