''Varanus salvadorii'', also known as the crocodile monitor, Papuan monitor and Salvadori's monitor, is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
monitor lizard
Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recogn ...
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to
New Guinea
New Guinea (; Hiri Motu
Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea).
It is a simplified version of ...
. It is the largest monitor lizard known from New Guinea, and is
one of the longest lizards in the world, verified at up to . The tail of the species is exceptionally long, so some specimens have been claimed to exceed the length of the world's largest lizard, the
Komodo dragon
The Komodo dragon (''Varanus komodoensis''), also known as the Komodo monitor, is a member of the monitor lizard family Varanidae that is endemic to the Indonesian islands of Komodo, Rinca, Flores, and Gili Motang. It is the largest extant ...
; however, ''V. salvadorii'' is far less massive.
''Varanus salvadorii'' is an
arboreal
Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...
lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
with a dark green body marked with bands of yellowish spots. It has a characteristic blunt snout and a very long tail. It lives in
mangrove swamp
Mangrove forests, also called mangrove swamps, mangrove thickets or mangals, are productive wetlands that occur in coastal intertidal zones. Mangrove forests grow mainly at tropical and subtropical latitudes because mangroves cannot withstand fre ...
s and
coastal
The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...
rainforest
Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...
s in the southeastern part of the island, feeding on
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
s, small
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s, eggs, and carrion. Its teeth are better adapted than those of most monitors for seizing fast-moving
prey
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...
. Like all monitors, ''V. salvadorii'' has anatomical features that enable it to breathe more easily when running than other lizards can, but it may have even greater stamina than most other monitor species. Little is known of its reproduction and development, as the species is difficult to breed in
captivity
Captivity, or being held captive, is a state wherein humans or other animals are confined to a particular space and prevented from leaving or moving freely. An example in humans is imprisonment. Prisoners of war are usually held in captivity by a ...
.
''V. salvadorii'' is threatened by
deforestation
Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...
and
poaching
Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights.
Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...
, and is protected by the
CITES
CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
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 tribesmen maintain that the monitor gives warnings if
crocodile
Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to inclu ...
s are nearby.
Taxonomy
''V. salvadorii'' was first described as ''Monitor salvadorii'' by
Wilhelm Peters
Wilhelm Karl Hartwich (or Hartwig) Peters (22 April 1815 in Koldenbüttel – 20 April 1883) was a German natural history, naturalist and explorer.
He was assistant to the anatomist Johannes Peter Müller and later became curator of the Natural ...
and
Giacomo Doria
Marquis Giacomo Doria (1 November 1840 – 19 September 1913) was an Italian naturalist, botanist, herpetologist, and politician.
He was the founder of the Museo Civico di Storia Naturale in Genoa in 1867, and director from then until his d ...
in 1878 based on a female specimen with a snout-to-vent length of , and a long tail.
It was subordinated to the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Varanus'' under the name ''Varanus salvadorii'' by
George Albert Boulenger
George Albert Boulenger (19 October 1858 – 23 November 1937) was a Belgian-British zoologist who described and gave scientific names to over 2,000 new animal species, chiefly fish, reptiles, and amphibians. Boulenger was also an active botani ...
in 1885.
Etymology
The generic name, ''Varanus'', is derived from the
Arabic
Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...
''waral'' (), meaning "lizard". The term "monitor" is thought to have come about from confusion between ''waral'' and the
German
German(s) may refer to:
* Germany (of or related to)
**Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ger ...
', meaning "warning". The term "goanna" came about as a corruption of the name "iguana". The
specific name, ''salvadorii'', is derived from a
Latinization of
Tommaso Salvadori
Count Adelardo Tommaso Salvadori Paleotti (30 September 1835 – 9 October 1923) was an Italian zoologist and ornithologist.
Biography
Salvadori was born in Porto San Giorgio, son of Count Luigi Salvadori and Ethelyn Welby, who was English. His ...
, an Italian ornithologist who worked in New Guinea.
Evolution
The evolutionary history of ''V. salvadorii'' started with the genus ''
Varanus'', which originated in Asia about 40 million years ago (Mya). Around 15 Mya, a
tectonic
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...
connection between Australia and
Southeast Asia
Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...
allowed the varanids to spread into what is now the Indonesian archipelago.
Based upon DNA sequences of three
nuclear
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
* Nuclear engineering
*Nuclear physics
*Nuclear power
*Nuclear reactor
*Nuclear weapon
*Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
*Nuclear space
*Nuclear ...
and two
mitochondrial
A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...
genes,
cladistic analysis
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived chara ...
identifies ''V. salvadorii'' as a member of a species cluster that includes the
lace monitor
The lace monitor or tree goanna (''Varanus varius'') is a member of the monitor lizard family native to eastern Australia. A large lizard, it can reach in total length and in weight. The lace monitor is considered to be a least-concern species ...
(''V. varius'') and the
Komodo dragon
The Komodo dragon (''Varanus komodoensis''), also known as the Komodo monitor, is a member of the monitor lizard family Varanidae that is endemic to the Indonesian islands of Komodo, Rinca, Flores, and Gili Motang. It is the largest extant ...
(''Varanus komodoensis'').
Morphological considerations suggest that ''
Varanus priscus
Megalania (''Varanus priscus'') is an extinct species of giant monitor lizard, part of the megafaunal assemblage that inhabited Australia during the Pleistocene. It is the largest terrestrial lizard known to have existed, reaching an estimated ...
'' was also a member of the group.
Monitors apparently colonized Australasia from Asia about 32 Mya; the ''varius'' clade then arose about 17 Mya.
The
Torres Strait
The Torres Strait (), also known as Zenadh Kes, is a strait between Australia and the Melanesian island of New Guinea. It is wide at its narrowest extent. To the south is Cape York Peninsula, the northernmost extremity of the Australian mai ...
separating New Guinea from Australia is less than long, a distance that could have been covered fairly easily with
island hopping
Leapfrogging, also known as island hopping, was a military strategy employed by the Allies in the Pacific War against the Empire of Japan during World War II.
The key idea is to bypass heavily fortified enemy islands instead of trying to captu ...
.
Distribution
The largest of the seven species of monitors found on the island of New Guinea, ''V. salvadorii'' occurs in both the state
Papua New Guinea
Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...
and the
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
n region of
West Papua. It inhabits the high and low canopies of the lowland rainforests and coastal
mangrove
A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...
swamps, sometimes venturing out of these areas during floods in the rainy seasons. No detailed field investigation data are available for ''V. salvadorii'', so the full extent of its range is unknown.
Its remote and generally inaccessible habitat is an obstacle to detailed study of this monitor in its natural
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
.
Biology and morphology
![Varanus salvadorii, Cincinnati Zoo](https://upload.wikimedia.org/wikipedia/commons/4/44/Varanus_salvadorii%2C_Cincinnati_Zoo.jpg)
The most characteristic feature of ''V. salvadorii'' is its blunt, bulbous snout, which makes it look different from every other monitor on New Guinea, and suggested the common name "tree crocodile".
The body of the lizard is dark green with rings of yellow spots.
The tail is banded yellow and black and is extremely long, more than twice as long as the snout-to-vent length.
Its teeth are long, straight, and sharp. Its claws are prominent and strongly curved. No clear external
sexual dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
is seen.
Various descriptions are mutually inconsistent, but agreement exists that ''V. salvadorii'' is unique among
extant
Extant is the opposite of the word extinct. It may refer to:
* Extant hereditary titles
* Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English
* Extant taxon, a taxon which is not extinct, ...
varanid species, in that the animal's tail is much longer than the snout-to-vent length in both juveniles and adults. One figure
gives the tail as two-thirds longer, whereas another states that the tail is 210% of the animal's body length.
At hatching, ''V. salvadorii'' is about long. Reports of the maximal length vary greatly and are the subject of much dispute. It possibly attains the greatest length among extant species of lizards, although it is considerably less massive than the Komodo dragon.
Specimens are known to reach at least in length.
but it has been claimed to grow much longer.
A specimen measuring reportedly was caught in
Konedobu
Konedobu is a suburb of Port Moresby, the capital of Papua New Guinea. It is located in the valley in between Touaguba Hill and Burns Peak.
The suburb is the location of numerous Government departments, including the headquarters of the Royal Pa ...
by Dr. F. Barker.
Claims that some specimens considerably exceed such lengths are so far unsupported.
Claims of ''V. salvadorii'' attaining large weights also are unverified; the species is much more slender than Komodo dragons of comparable length.
The typical reported length of this species is less than with a matching body mass of about . Ten adult specimens were found to weigh only at a length of , so even the aforementioned weight is fairly optimistic for this species. However, these specimens were not fully mature since wild caught specimen have been known to grow over and breeders of this lizard have estimated that wild specimens can weigh up to . The average size of ''V. salvadorii'' caught in one study was with a weight of , but these must have been young specimens.
''Varanus salvadorii'' has mammal-like
aerobic
Aerobic means "requiring air," in which "air" usually means oxygen.
Aerobic may also refer to
* Aerobic exercise, prolonged exercise of moderate intensity
* Aerobics, a form of aerobic exercise
* Aerobic respiration, the aerobic process of cellu ...
abilities; a positive pressure
gular pump in the animal's throat assists lung ventilation.
Unlike most lizards that cannot breathe efficiently while running, because of
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 the sideways flexing expands one lung ...
, the gular pump of monitor lizards enables them to overcome the effect of one lung at a time being compressed by their running gait.
The evolutionary development of the gular pump is functionally analogous to that of the diaphragm in mammals, which ventilates the lung independently of locomotion. ''V. salvadorii'' may be the species that achieves the greatest running endurance as a result of its gular pump.
Investigation supports the idea that gular breathing is an evolutionary development that masks the effect of Carrier's constraint.
Behavior
![CrocMonitor](https://upload.wikimedia.org/wikipedia/commons/e/e0/CrocMonitor.jpg)
''V. salvadorii'' is a highly
arboreal
Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...
lizard. It can hang onto branches with its rear legs, and occasionally use its tail as a
prehensile
Prehensility is the quality of an appendage or organ (anatomy), organ that has Adaptation (biology), adapted for grasping or holding. The word is derived from the Latin term ''prehendere'', meaning "to grasp". The ability to grasp is likely der ...
grip. The primary function of the tail, however, is as a counterbalance when leaping from branch to branch.
As in some other ''Varanus'' species, the tail also may be used for defense, as captive specimens may attempt to lash keepers with their tails.
This species occasionally is seen in the pet trade, but has a reputation for aggression and unpredictability.
Although they are known to rest and bask in trees, they sleep on the ground or submerged in water.
These monitors rise up on their hind legs to check their surroundings, behavior that also has been documented in
Gould's monitor
The sand goanna (''Varanus gouldii'') is a species of large Australian monitor lizard, also known as Gould's monitor, sand monitor, or racehorse goanna.
Taxonomy
John Edward Gray described the species in 1838 as ''Hydrosaurus gouldii'', notin ...
s (''V. gouldii'').
They are known to exhibit a warning posture, in which they carry their tails rolled up behind them. According to native belief, they give a warning call if they see crocodiles.
In general ''V. salvadorii'' avoids human contact, but its bite is capable of causing infection, like the Komodo dragon's.
One fatality was 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 those of other monitor species, which typically are blunt, peglike, and face slightly rearward.
Their upper teeth are long, fang-like, set vertically in the jawbone, adapted to hooking into fast-moving prey such as birds, bats, and rodents. Their lower teeth are housed in a fleshy sheath. In the wild, ''V. salvadorii'' is the
top predator
An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own.
Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...
in New Guinea, feeding on birds (particularly ''
Cacatua
''Cacatua'' is a genus of cockatoos found from the Philippines and Wallacea east to the Solomon Islands and south to Australia. They have a primarily white plumage (in some species tinged pinkish or yellow), an expressive crest, and a black (sub ...
'' sp. and
maleo
The maleo (''Macrocephalon maleo'') is a large megapode and the only member of the monotypic genus ''Macrocephalon''. The maleo is endemic to Sulawesi and the nearby smaller island of Buton in Indonesia. It is found in the tropical lowland and ...
s (''Macrocephalon maleo'')),
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
, small mammals, and
carrion
Carrion () is the decaying flesh of dead animals, including human flesh.
Overview
Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...
.
Natives have reported that it can take down pigs,
deer
Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
, and hunting dogs, and hauls its prey into the canopy to consume it.
Captive specimens have been known to eat
fish
Fish are aquatic, craniate, gill-bearing 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. Approximately 95% of li ...
,
frog
A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...
s,
rodent
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...
s, chickens, and dog food.
This species has been observed hunting prey in a unique fashion for monitor lizards.
Rather than following its prey to ambush it from behind, ''V. salvadorii'' may stalk its prey and anticipate where it will run, meeting it headlong.
Reproduction
Reproduction of ''V. salvadorii'' has only been observed in captivity, so nothing is known about its reproduction in the wild. The egg clutches, comprising four to 12 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 , while weight may vary from . Most clutches laid in captivity have been infertile, and only four successful breedings have been documented thus far. Hatchlings are about long and weigh around . Like those of many other monitors, the hatchlings of ''V. salvadorii'' are more colorful than adults, and feed primarily on insects and small reptiles.
Conservation
''Varanus salvadorii'' is currently protected under the
CITES
CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
Appendix II,
which requires an exportation permit for international trade. It is not listed on the
IUCN
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
Red List or the
Endangered Species Act
The Endangered Species Act of 1973 (ESA or "The Act"; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of ec ...
.
It faces threats from deforestation and poaching, as it is hunted and skinned alive by native peoples, who consider the monitor an evil spirit that "climbs trees, walks upright, breathes fire, and kills men", to make drums .
In 2008, 52 individuals were maintained at 17 zoological parks in the United States, with an unknown number in private collections.
References
Honoluluzoo.org
{{Taxonbar, from=Q940883
Varanus
Reptiles of Indonesia
Monitor lizards of New Guinea
Reptiles described in 1878
Taxa named by Wilhelm Peters
Taxa named by Giacomo Doria
Endemic fauna of New Guinea
Apex predators