Stump-tailed skink
Encyclopedia
Tiliqua rugosa is a short-tailed, slow moving species of blue-tongued skink found in Australia
. Three of the four recognized subspecies
are found only in Western Australia
, where they are known collectively by the common name bobtail. The name shingleback is also used, especially for T. rugosa asper, the only subspecies native to eastern Australia
.
T. rugosa has a heavily armoured body and can be found in various colours, ranging from dark brown to cream. It has a short, wide stumpy tail that resembles its head and may confuse predators. The tail also contains fat reserves, which are drawn upon during hibernation
in winter. This skink is an omnivore
that eat snail
s and plants and spends much of its time browsing through vegetation for food. It is often seen sunning itself on roadsides or other paved areas.
Apart from bobtail and shingleback a variety of other common names are used, including stump-tailed skink, bogeye, pinecone lizard and sleepy lizard.
in 1825 as Trachydosaurus rugosus. It has since been reclassified as Tiliqua rugosa. Some herpetologists claim this species has more common names than any other lizard.
are currently recognized:
and Western Australia. The range extends from Shark Bay, Western Australia
, across the southern-most regions of the country to the coast, then north into Queensland
. Four subspecies are found in Western Australia, including one at Rottnest Island
. It also occurs in the eastern states of Victoria and New South Wales
, but does not reach coastal areas.
The habitat of the species includes shrubland and desert grassland to sandy dunes. These skinks are well known, due to a preference for sun basking and open areas, and are often seen along roadsides or other cleared areas in its range.
It has a triangular shaped head, and a bright blue tongue. Its short stumpy tail is similar in shape to its head. This possibly evolved as a defence mechanism against predators and has led to the common name of "two-headed skink". Their short tail also contains fat reserves, which the lizard lives upon during hibernation in winter. Unlike many skinks, shinglebacks do not exhibit autotomy
and cannot shed their tails .
that eat snails, insects, carrion
, vegetation and flowers. The species was once preyed upon by dingo
s, Australian pythons such as Morelia spilota, and local peoples; a threat is now more likely to come from large introduced feral
species such as fox
es and cat
s.
They have been know to eat human food such as sausage and chicken as well as fruits such as banana and passionfruit.
, giving birth to broods of 1 to 4 relatively large offspring. Unlike most lizards, the species tends to be monogamous extending outside the breeding season
of September through November; such pairs have been known to return to each other every year for up to 20 years.
Upon being born, the newborn young immediately consume their afterbirth. The young stay with their parents for several months before moving on, however they remain in close proximity forming a colony of closely related skinks.
The male of a monogamous pair eats less while parenting, remaining alert and ready to give an alarm.
Single unit recordings from the auditory nerve show both spontaneous and nonspontaneous responses. The spontaneous fibers exhibited multimodal interval histograms and responded to a tone burst by an initial rate increase, an after-inhibition, and a rebound. Tuning curves show peak sensitivity between 700 Hz and 3 kHz. A marked seasonal dependence on the number of responsive fibers correlates well with the increase of summating potential found to occur during early spring. The absolute sensitivity is quite high, with thresholds below 25 db sound pressure level. The most sensitive fiber respond to the rustle of clothing a few feet away.
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...
. Three of the four recognized 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...
are found only in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, where they are known collectively by the common name bobtail. The name shingleback is also used, especially for T. rugosa asper, the only subspecies native to eastern Australia
Eastern states of Australia
In Australia, the term eastern states refers to the states adjoining the east coast of Australia. These are the mainland states of New South Wales, Queensland and Victoria. The Australian Capital Territory and Jervis Bay Territory, while not states, are also included. The term usually includes the...
.
T. rugosa has a heavily armoured body and can be found in various colours, ranging from dark brown to cream. It has a short, wide stumpy tail that resembles its head and may confuse predators. The tail also contains fat reserves, which are drawn upon during hibernation
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...
in winter. This skink is an omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
that eat snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s and plants and spends much of its time browsing through vegetation for food. It is often seen sunning itself on roadsides or other paved areas.
Apart from bobtail and shingleback a variety of other common names are used, including stump-tailed skink, bogeye, pinecone lizard and sleepy lizard.
Etymology and taxonomy
The species was first described by John Edward GrayJohn Edward Gray
John Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....
in 1825 as Trachydosaurus rugosus. It has since been reclassified as Tiliqua rugosa. Some herpetologists claim this species has more common names than any other lizard.
Subspecies
Four subspeciesSubspecies
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...
are currently recognized:
- Tiliqua rugosa rugosa
- Bobtail or Western Shingleback: Western AustraliaWestern AustraliaWestern Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
- Tiliqua rugosa asper
- Eastern Shingleback: eastern AustraliaEastern states of AustraliaIn Australia, the term eastern states refers to the states adjoining the east coast of Australia. These are the mainland states of New South Wales, Queensland and Victoria. The Australian Capital Territory and Jervis Bay Territory, while not states, are also included. The term usually includes the...
- Tiliqua rugosa konowi
- Rottnest Island Bobtail/Rottnest Island Shingleback: Rottnest IslandRottnest IslandRottnest Island is located off the coast of Western Australia, near Fremantle. It is called Wadjemup by the Noongar people, meaning "place across the water". The island is long, and at its widest point with a total land area of . It is classified as an A Class Reserve and is managed by the...
, Western Australia- Tiliqua rugosa palarra
- Northern Bobtail/Shark Bay Shingleback: Shark BayShark Bay, Western AustraliaShark Bay is a World Heritage Site in the Gascoyne region of Western Australia. It is an area centred approximately on , 800 kilometres north of Perth, on the westernmost point of Australia. An expedition led by Dirk Hartog happened upon the area in 1616, becoming the second group of Europeans...
, Western Australia
Distribution and habitat
The species is widely distributed in arid to semi-arid regions of southernSouthern Australia
The term southern Australia is generally considered to include the States and territories of Australia of New South Wales, Victoria, South Australia, Tasmania and the Australian Capital Territory...
and Western Australia. The range extends from Shark Bay, Western Australia
Shark Bay, Western Australia
Shark Bay is a World Heritage Site in the Gascoyne region of Western Australia. It is an area centred approximately on , 800 kilometres north of Perth, on the westernmost point of Australia. An expedition led by Dirk Hartog happened upon the area in 1616, becoming the second group of Europeans...
, across the southern-most regions of the country to the coast, then north into Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
. Four subspecies are found in Western Australia, including one at Rottnest Island
Rottnest Island
Rottnest Island is located off the coast of Western Australia, near Fremantle. It is called Wadjemup by the Noongar people, meaning "place across the water". The island is long, and at its widest point with a total land area of . It is classified as an A Class Reserve and is managed by the...
. It also occurs in the eastern states of Victoria and New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, but does not reach coastal areas.
The habitat of the species includes shrubland and desert grassland to sandy dunes. These skinks are well known, due to a preference for sun basking and open areas, and are often seen along roadsides or other cleared areas in its range.
Description
Tiliqua rugosa has a heavily armoured body and can be found in various colours, ranging from dark brown to cream. Its total length seldom exceeds 18 or 25 inches, but it is a very heavy-bodied lizard for its length.It has a triangular shaped head, and a bright blue tongue. Its short stumpy tail is similar in shape to its head. This possibly evolved as a defence mechanism against predators and has led to the common name of "two-headed skink". Their short tail also contains fat reserves, which the lizard lives upon during hibernation in winter. Unlike many skinks, shinglebacks do not exhibit autotomy
Autotomy
Autotomy or self amputation is the act whereby an animal severs one or more of its own appendages, usually as a self-defense mechanism designed to elude a predator's grasp...
and cannot shed their tails .
Diet
Tiliqua rugosa is an omnivoreOmnivore
Omnivores are species that eat both plants and animals as their primary food source...
that eat snails, insects, 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...
, vegetation and flowers. The species was once preyed upon by dingo
Dingo
The Australian Dingo or Warrigal is a free-roaming wild dog unique to the continent of Australia, mainly found in the outback. Its original ancestors are thought to have arrived with humans from southeast Asia thousands of years ago, when dogs were still relatively undomesticated and closer to...
s, Australian pythons such as Morelia spilota, and local peoples; a threat is now more likely to come from large introduced feral
Feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
species such as fox
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
es and cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s.
They have been know to eat human food such as sausage and chicken as well as fruits such as banana and passionfruit.
Reproduction
Tiliqua rugosa is a viviparous skinkSkink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...
, giving birth to broods of 1 to 4 relatively large offspring. Unlike most lizards, the species tends to be monogamous extending outside the breeding season
Breeding season
The breeding season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding among some wild animals and birds . Species with a breeding season have naturally evolved to have sexual intercourse during a certain time of year in order to achieve the...
of September through November; such pairs have been known to return to each other every year for up to 20 years.
Upon being born, the newborn young immediately consume their afterbirth. The young stay with their parents for several months before moving on, however they remain in close proximity forming a colony of closely related skinks.
The male of a monogamous pair eats less while parenting, remaining alert and ready to give an alarm.
Hearing
The hearing of T. rugosus, can be measured at the round window as cochlear microphonics and summating potential (of the cochlea), and compound action potential (of the auditory nerve). These indicate a probable best hearing range of 750–3000 Hz. When pairs of sine wave tone bursts were sounded, the amplitude and latency of the neural response to the second tone burst were greatly increased. This may indicate a greater (behavioural) sensitivity to a second sound. The summating potential was very sensitive to season, increasing ten-fold during spring.Single unit recordings from the auditory nerve show both spontaneous and nonspontaneous responses. The spontaneous fibers exhibited multimodal interval histograms and responded to a tone burst by an initial rate increase, an after-inhibition, and a rebound. Tuning curves show peak sensitivity between 700 Hz and 3 kHz. A marked seasonal dependence on the number of responsive fibers correlates well with the increase of summating potential found to occur during early spring. The absolute sensitivity is quite high, with thresholds below 25 db sound pressure level. The most sensitive fiber respond to the rustle of clothing a few feet away.