Argus monitor
Encyclopedia
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.
There are at least two Australian subspecies
: the one in Western Australia is Varanus panoptes rubidus (rubidus referring to its reddish coloration), while the subspecies from Arnhem Land
, the Kimberley and Cape York Peninsula
is Varanus panoptes panoptes. The New Guinea
variety is Varanus panoptes horni.
, with the female reaching an average total length of three feet (90 cm), while the male reaches an average of 4–5 feet (120–140 cm), the larger sized animals being V. panoptes panoptes vs. V. panoptes horni. It is a reasonably lean monitor and does not put on the bulk that its African cousins often do. Most Argus Monitors are yellow in color, with a background of brown or dark tan. Their color often varies with place of origin or even the individual.
s. They are primarily terrestrial, meaning they spend a great deal of time on the ground. This species is an avid digger and will dig large burrows or take over an already existing one, where they spend a sizable portion of their time. Despite all this, they will eagerly forage
in trees and in the water. These large lizards are quite fast and will run up to 100 yards/meters to the nearest tree or burrow when they are chased. The Argus Monitor is riparian in habits and as such, it can usually be found around a permanent source of water. The Argus will often "tripod" in captivity (animal)
and in the wild, raising up on their hind legs and supporting themselves with the tail. This unusual behavior is used to spot potential prey or enemies from a distance or when they are threatened. They exhibit this behavior on a regular basis in captivity. This habit provides them a unique characteristic that separates them from most other monitors.
In Arnhem Land
, they lay 6 to 13 eggs
between January and February.
Its prey consists of almost anything that it can overpower. This includes fish
, crab
s, small birds, rodents, insects and even other monitors
. The Argus Monitor frequently preys on the dwarf monitors that it shares its range with. Spiny-tailed goannas and rock monitors are eaten on a regular basis. Argus Monitors have great senses, with smell being the most acute. Like all monitors, the Argus has a forked tongue and a vomeronasal organ
in the roof of its mouth. It uses this organ in the same manner as snakes do and can often be seen flicking their tongues in search of a meal.
With such a voracious appetite, the Argus Monitor makes for an interesting animal and is great for breeding programs. Argus Monitors will often attack one's hand if they have not been fed recently. They are often thought to be "bottomless pits" because they can fit amazing amounts of food in their stomachs.
Recent studies suggest that the Cane Toad
infestation has severely damaged the population of Argus Monitors within the Top End
. It is estimated that numbers have dropped by as much as 90% in many areas.
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 northern regions of 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...
and southern 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 commonly known as the Yellow-spotted Monitor.
There are at least two Australian subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
: the one in Western Australia is Varanus panoptes rubidus (rubidus referring to its reddish coloration), while the subspecies from Arnhem Land
Arnhem Land
The Arnhem Land Region is one of the five regions of the Northern Territory of Australia. It is located in the north-eastern corner of the territory and is around 500 km from the territory capital Darwin. The region has an area of 97,000 km² which also covers the area of Kakadu National...
, the Kimberley and Cape York Peninsula
Cape York Peninsula
Cape York Peninsula is a large remote peninsula located in Far North Queensland at the tip of the state of Queensland, Australia, the largest unspoilt wilderness in northern Australia and one of the last remaining wilderness areas on Earth...
is Varanus panoptes panoptes. The 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...
variety is Varanus panoptes horni.
Physical characteristics
The size of an Argus Monitor differs greatly between the sexesSexual 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:...
, with the female reaching an average total length of three feet (90 cm), while the male reaches an average of 4–5 feet (120–140 cm), the larger sized animals being V. panoptes panoptes vs. V. panoptes horni. It is a reasonably lean monitor and does not put on the bulk that its African cousins often do. Most Argus Monitors are yellow in color, with a background of brown or dark tan. Their color often varies with place of origin or even the individual.
Behavior
The Argus Monitor is a versatile predator and inhabits a large variety of biomes and habitatHabitat
* 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...
s. They are primarily terrestrial, meaning they spend a great deal of time on the ground. This species is an avid digger and will dig large burrows or take over an already existing one, where they spend a sizable portion of their time. Despite all this, they will eagerly forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...
in trees and in the water. These large lizards are quite fast and will run up to 100 yards/meters to the nearest tree or burrow when they are chased. The Argus Monitor is riparian in habits and as such, it can usually be found around a permanent source of water. The Argus will often "tripod" in captivity (animal)
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...
and in the wild, raising up on their hind legs and supporting themselves with the tail. This unusual behavior is used to spot potential prey or enemies from a distance or when they are threatened. They exhibit this behavior on a regular basis in captivity. This habit provides them a unique characteristic that separates them from most other monitors.
In Arnhem Land
Arnhem Land
The Arnhem Land Region is one of the five regions of the Northern Territory of Australia. It is located in the north-eastern corner of the territory and is around 500 km from the territory capital Darwin. The region has an area of 97,000 km² which also covers the area of Kakadu National...
, they lay 6 to 13 eggs
Egg (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...
between January and February.
Its prey consists of almost anything that it can overpower. This includes 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...
, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, small birds, rodents, insects and even other monitors
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...
. The Argus Monitor frequently preys on the dwarf monitors that it shares its range with. Spiny-tailed goannas and rock monitors are eaten on a regular basis. Argus Monitors have great senses, with smell being the most acute. Like all monitors, the Argus has a forked tongue and a vomeronasal organ
Vomeronasal organ
The vomeronasal organ , or Jacobson's organ, is an auxiliary olfactory sense organ that is found in many animals. It was discovered by Frederik Ruysch and later by Ludwig Jacobson in 1813....
in the roof of its mouth. It uses this organ in the same manner as snakes do and can often be seen flicking their tongues in search of a meal.
With such a voracious appetite, the Argus Monitor makes for an interesting animal and is great for breeding programs. Argus Monitors will often attack one's hand if they have not been fed recently. They are often thought to be "bottomless pits" because they can fit amazing amounts of food in their stomachs.
Recent studies suggest that the Cane Toad
Cane Toad
The Cane Toad , also known as the Giant Neotropical Toad or Marine Toad, is a large, terrestrial true toad which is native to Central and South America, but has been introduced to various islands throughout Oceania and the Caribbean...
infestation has severely damaged the population of Argus Monitors within the Top End
Top End
The Top End of northern Australia is the second northernmost point on the continent. It covers a rather vaguely-defined area of perhaps 400,000 square kilometres behind the northern coast from the Northern Territory capital of Darwin across to Arnhem Land with the Indian Ocean on the west, the...
. It is estimated that numbers have dropped by as much as 90% in many areas.