Eastern blue-tongued lizard

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Eastern blue-tongued skink
Eastern blue tongued lizard.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Scincidae
Genus: Tiliqua
Species:
Subspecies:
T. s. scincoides
Trinomial name
Tiliqua scincoides scincoides
(White, 1790) [1]

The Tiliqua scincoides scincoides, or eastern blue-tongued lizard, is native to Australia. Its blue tongue can be used to warn off predators. In addition to flashing its blue tongue, the skink hisses and puffs up its chest to assert dominance and appear bigger when in the presence of its predators such as large snakes and birds. The eastern blue tongue is ovoviviparous and precocial, meaning that its young are more developed and advanced at their time of birth. The Tiliqua scincoides scincoides is not venomous to humans and can be found in suburban and urban areas, specifically in house gardens.

Contents

Nomenclature

The eastern blue-tongued lizard (Tiliqua scincoides scincoides) is a species of skink in the genus Tiliqua. The Tiliqua scincoides scincoides can also be called the common blue tongue, the eastern bluetongue, the eastern blue-tongued lizard, or skink. [1] The Tiliqua scincoides scincoides is in the Animalia kingdom, the Chordata phylum, the Reptilia class, the Squamata order, the Scincidae family, the Tiliqua genus, the T Scincoides species, and the T. s. Scincoides subspecies.

Appearance

Eastern blue-tongued skink in the Leipzig Zoological Garden, Leipzig, Germany Tiliqua scincoides (White, 1790).jpg
Eastern blue-tongued skink in the Leipzig Zoological Garden, Leipzig, Germany

The eastern blue-tongued lizard has a short body and short legs. This lizard weighs approximately 1 kilogram and extends approximately 60 centimeters. [2] 36cm of the 60 cm are the lizards' head and body. [2] The snout-vent length is 300-320mm and the hind limb length makes up 20% of snout-vent length. The skinks have tails that are short and robust. [3] In other words, the length of the hind legs are roughly 62 mm while the tail length is approximately 195mm and makes up 50-75% of the snout-vent length. [4]

The lizard can have different colors, but its pattern frequently appears to be banded. The tongue of the lizard is a blue color and can appear to have a hint of violet. [5] This blue tongue is used to alarm predators and scare them off. The eastern blue-tongue lizard has smooth skin covered with scales that overlap and have small bone plates. [2] The ventral (abdominal) region of the lizard is a silver or gray color. The lizard's back, however, appears dark brown and cream-colored and its head is pale brown. [5] Across its body, the eastern-blue-tongued lizard has broad black and brown bands. [2] This lizard can generally be identified by its black stripe that extends from its eye to its tympanum (exposed eardrum), and sometimes all the way to the side of the lizard's neck. [2] The lizards blue tongues could be an evolutionary adaptation that can assist in long distance communication in order warn off predators and decrease aggressive activity. [6]

Habitat

Eastern blue-tongued lizard Tiliqua scincoides scincoides 01.jpg
Eastern blue-tongued lizard

Tiliqua scincoides scincoides are found in the coastal plain and lower Blue Mountains in Sydney, Australia and in the majority of New South Wales and Cobar. [2] Eastern blue tongues frequent in the open country and take shelter among large objects on the ground like logs or rocks or among leaf litter. [2] Blue tongued lizards are incapable of producing their own body heat, as are all lizards. Because of this, they spend their mornings in the sun before looking for food in order to maintain their body temperature which is between 30-35 degrees Celsius when they are active. [2] In the winter, however, when the weather is cold, lizards bury themselves in their shelter sites and are not active. These lizards only leave their shelters on days where the sun is out, so that they can bask in the sun. [2] They infrequently leave the comfort of their hollow logs and ground debris. [7]

Temperature regulation

Eastern blue-tongued lizard Eastern blue-tongued lizard (Tiliqua scincoides scincoides) - 2022 werrington lake reserve sydney.jpg
Eastern blue-tongued lizard

Tiliqua scincoides scincoides are behaviorally regulated by their internal temperature which is a direct result of the peripheral temperature and the temperature of their brains. In a study done in 1969, the behavior of this species was observed between warm and cold environments. The results of this study suggested that when the lizards were inactive, they chose to move to a place that was cooler, therefore causing their internal temperatures to decrease. [8] When their internal temperatures reached a reproducible level when in heat, they decided to return to a more neutral environment. [8] It has also been found that juvenile lizards utilize higher environmental temperatures and thermo-regulate more often than adult lizards. [4]

Conservation status

Eastern blue-tongued lizard Eastern blue-tongued lizard - Tiliqua scincoides scincoides - 4.jpg
Eastern blue-tongued lizard

Eastern blue tongued lizards may eat poisonous snails and slugs that have been tainted by snail baits. [2] If these lizards are living in a garden, they may be exposed to snail baits and insecticides that can cause them harm. [2] Because blue tongued lizards are able to squirm through small holes in fences and under fences, they may be faced with garden pests or chemicals used by neighbors. [2] When these lizards are kept as pets, they often are attracted to horizontal pipes, cavities under houses, and rockeries as hiding sites. [2] The Tiliqua scincoides scincoides shows signs of having a stable population, whereas its sister species, the Tiliqua scincoides intermedia appears to have a population that is declining. [4] In Australia, there has been a ban on exportation and trading of reptiles. [4] Although there is a ban, the blue tongue is a very popular lizard to trade due its unique tongue color.

According to a consensus published in 2017 by the San Diego Zoo Wildlife Alliance Library, the eastern blue-tongued lizard has a wide distribution and it is categorized as “least concern” in terms of endangerment. Regardless of their stable population, these lizards are protected in Australia as a native species. Government regulations like the Environment Protection and Biodiversity Conservation Act in 1999 have positively influenced the preservation of the eastern blue-tongued lizard. [9]

Eastern blue-tongued lizard Eastern blue-tongued lizard - Tiliqua scincoides scincoides - 7.jpg
Eastern blue-tongued lizard

Close relatives

Eastern blue-tongued lizard Eastern blue-tongued lizard - Tiliqua scincoides scincoides - 6.jpg
Eastern blue-tongued lizard

This specific species is closely related to 2 other species, Tiliqua scincoides intermedia and Tiliqua scincoides chimaera.  However, they have different habitats. The Tiliqua scincoides scincoides is native to southern and eastern Australia. [10] On the other hand, the Tiliqua scincoides intermedia is native to northern Australia and the Tiliqua scincoides chimaera is native to the Maluku Province in Indonesia. [10] These lizards are found in mixed woodland habitats, semi-deserts, and scrubland areas in Tasmania, Australia, and New Guinea. [5] They can also be found habituating in terrestrial biomes such as scrub forests, grasslands, or the savanna. [5]

Diet

As an omnivore, the blue tongued skink has a diet that consists of plants, fruits, insects, and other reptiles. Captive studies have been conducted and have shown that high quality dog food is one of the best food sources for these lizards as it has extra minerals and vitamins. [5]   These lizards eat during the day and have been labeled as diurnal. [5] Because eastern blue tongued lizards are agile, they frequently consume animals that move more slowly. Typically, they tend to munch on snail shells and beetles. They are able to do so because their jaw muscles are strong and their teeth are large. [2] These lizards also eat crickets and wax worms. [7]

Eastern blue-tongued lizard Eastern blue-tongued lizard - Tiliqua scincoides scincoides - 2.jpg
Eastern blue-tongued lizard

Reproductive cycle and parental care

The eastern blue tongue becomes sexually mature between 561 and 590 days. [4] The Tiliqua scincoides scincoides is said to be ovoviviparous because the mother lays live young that are more developed than the typical offspring as the young have spent more time developing inside of the mother.The Tiliqua scincoides scincoides is reported to be ovoviviparous, which means eastern blue tongue embryos develop inside eggs that are retained within the mother's body until they are hatched.  Since baby lizards are born in this mode, there is no risk of predators stealing the eggs. On average, each female has about 10 offspring and due to this process, the offspring all have an elevated level of survival. [5] Female lizards give birth to 6-20 young per year. [7] Similar to other animals, these offspring are nourished by the primitive placenta. [7]

Tiliqua scincoides scincoides are precocial species, meaning that they are born at a more advanced developmental stage and therefore do not require as much parental care because their brain is mostly developed at the time of their birth, unlike altricial species. A study done on these lizards found that adults and juveniles are able to distinguish between color and shape stimuli successfully and one was not superior in learning capabilities. [10] This study highlights the idea that Tiliqua scincoides scincoides are behaviorally flexible and adaptable in both adulthood and youth, specifically in reversal learning. These results, however, did not support the formation of an attentional set. [10]

Eastern blue-tongued lizard Blue Tongue Lizard (11905047974).jpg
Eastern blue-tongued lizard

Interestingly enough, research has been done that has shown that sexual maturity occurs at different body sizes depending on the location that a male Tiliqua scincoides scincoides resides. For example, it was found that sexuality maturity happens at smaller body sizes in southern part of Australia than in Queensland. [11]

Lifespan

In captivity, the eastern blue-tongued lizard can live in excess of 20 years. [12]

Eastern blue-tongued lizard Eastern blue-tongued lizard - Tiliqua scincoides scincoides - 3.jpg
Eastern blue-tongued lizard

Predators and parasites

Reptile ticks

Blue tongued lizards can be attacked by reptile ticks which attach under their scales or inside of their ear canal. [2] These reptile ticks do not cause paralysis and do not latch onto mammals, only onto reptiles. Other than ticks, mites and nematode worms are also parasites to the eastern blue tongue. [4]

Other predators

Blue tongues fall prey to large snakes and large predatory birds. The large snakes include the mulga snake (Pseudechis australis), the red bellied black snake, the black headed python (Aspidites malanocephalus), and the eastern brown snake [2] [4] The large predatory birds include the laughing kookaburras and brown falcons. [2] [4] Eastern blue tongued lizards can also be eaten by feral dogs and cats. Other predators of the eastern blue tongue include goannas, dingoes, and domestic cats and dogs.

Behavior and physiology

Tiliqua scincoides scincoides show very little aggression and are said to be docile and shy. [7] The eastern blue tongued lizard has a blue tongue in order to scare off potential predators. When predators approach the lizard, it opens its mouth and sticks out its blue tongue to warn off predators showing that it may be distasteful. [5] The lizards also hiss, which adds fear to any potential predators. [7]

Many methods have been explored in order to best categorize lizards as male or female.  Lizard sex can be determined non invasively by measuring head width, snout-vent length, weight, and trunk length. Specifically, ratios of head width to snout-vent length and head width to trunk length can be calculated to determine the sex of the blue tongued eastern lizard. [13]

Studies have been done that show that reptiles are capable of feeling human like feelings such as anxiety and pleasure among other emotions. [14]

Protective coloration

It has been hypothesized that the Tiliqua scincoides scincoides has a blue tongue in order to mimic the Death Adder, which shares some characteristics with the lizard, and is venomous. The Death Adder and the tiliqua scincoides scincoides have very similar coloration. Additionally, since this type of lizard has very short legs, it does look very similar to a snake. [5] The Tiliqua scincoides scincoides hisses loudly and puffs up its chest to appear larger and assert dominance. This lizard species can also lose its tail during a quarrel and regrow it. It typically takes a year for their tail to regrow. [7] In terms of breeding, the Tiliqua scincoides scincoides spend most of their time alone. However, September, October, and November are mating months. These months consist of fights between males in order to attain their first choice female. [2] More research needs to be done on whether the skinks blue tongue is a result of an adaptation that is anti-predatory or if it serves as infraspecific communication. Studies have been done, however, that have supported the idea that the amount of melanin that is present in the skink's skin does not heavily effect tongue coloration [15] Another interesting finding is that blue colored tongues have similar chromatic qualities to UV blue skin patches and can be reflective. [15] Another finding from this 2015 study is that “UV blue tongues are more conspicuous than pink tongues, especially in the visual model of conspecifics”. [15]

Olfaction

The eastern blue tongue skink has an olfactory epithelium that appears to be of the pseudo stratified type and is loosely packed. [16] The underlying Bowman glands and other supporting cells secrete to the olfactory epithelium's surface which has cilia from sensory cells and microvilli from supporting cells. [16]

Venom

Tiliqua scincoides scincoides are not venomous or deadly to humans. Bites from this skink will cause pain and leave a bruise, however it will not cause any long term effects. [2]

Interactions with humans and livestock

The eastern blue tongue can adapt to suburban living as well as cities. The skink can be found in gardens or basking in the sun on roads or drain pipes. [4] As the Tiliqua scincoides scincoides can live in urban areas, it can face injury from house pets such as cats and dogs, be hit by cars, or harmed by gardening tools. [4]

Related Research Articles

<span class="mw-page-title-main">Skink</span> Family of reptiles

Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. Skinks are characterized by their smaller legs in comparison to typical lizards and are found in different habitats except arctic and subarctic regions.

<span class="mw-page-title-main">Pink-tongued skink</span> Species of lizard

The pink-tongued skink is a species of lizard in the family Scincidae. It is endemic to Australia, where it is also called commonly the pink-tongued lizard. As suggested by these common names, its distinguishing characteristic is a pink tongue as opposed to the blue tongue of lizards of the closely related genus Tiliqua.

<span class="mw-page-title-main">Blue-tongued skink</span> Genus of lizards

Blue-tongued skinks comprise the Australasian genus Tiliqua, which contains some of the largest members of the skink family (Scincidae). They are commonly called blue-tongued lizards or simply blue-tongues or blueys in Australia or panana in Indonesia. As suggested by these common names, a prominent characteristic of the genus is a large blue tongue that can be bared as bluff-warning to potential enemies. The type of predator/threat that is near will determine the intensity of colour present in the tongue. The tongue can also deform itself and produce a thick mucus in order to catch prey. They are relatively shy in comparison with other lizards, and also significantly slower due to their shorter legs.

<span class="mw-page-title-main">Blotched blue-tongued lizard</span> Species of lizard


The blotched blue-tongued lizard, also known as the southern blue-tongued lizard or blotched blue-tongued skink is a blue-tongued skink endemic to south-eastern Australia.

<i>Tiliqua rugosa</i> Species of lizard

Tiliqua rugosa, most commonly known as the shingleback skink or bobtail lizard, is a short-tailed, slow-moving species of blue-tongued skink endemic to Australia. It is commonly known as the shingleback or sleepy lizard. Three of its four recognised subspecies are found in Western Australia, where the bobtail name is most frequently used. The fourth subspecies, T. rugosa asper, is the only one native to eastern Australia, where it goes by the common name of the eastern shingleback.

<span class="mw-page-title-main">Western blue-tongued lizard</span> Species of lizard

The western blue-tongued lizard, also known as the western blue-tongued skink, is a large skink native to Australia. It is one of six species of blue-tongued skinks found in Australia, though further species are found in New Guinea and Indonesia.

<span class="mw-page-title-main">Northern blue-tongued skink</span> Subspecies of lizard

The northern blue-tongued skink or northern blue-tongued lizard is the largest and heaviest of the blue-tongued lizards. They are native to Australia and found almost exclusively in the Northern Region. They generally live around 20 years and are commonly kept as pets.

<span class="mw-page-title-main">Adelaide pygmy blue-tongue skink</span> Species of lizard

The Adelaide pygmy blue-tongue skink or pygmy bluetongue is a species of skink, a lizard in the family Scincidae. The species was previously thought to be extinct and only rediscovered in 1992. Known locations of the species extend from Kapunda in the Light River valley, about 77 kilometres (48 mi) north east of Adelaide, northwards to Peterborough, about 254 kilometres (158 mi) north of Adelaide.

<span class="mw-page-title-main">Eastern three-lined skink</span> Species of lizard

The eastern three-lined skink, also known commonly as the bold-striped cool-skink, is a species of skink, a lizard in the family Scincidae. The species is endemic to Australia. A. duperreyi has been extensively studied in the context of understanding the evolution of learning, viviparity in lizards, and temperature- and genetic-sex determination. A. duperreyi is classified as a species of "Least Concern" by the IUCN.

<span class="mw-page-title-main">Southern water skink</span> Species of lizard

The southern water skink, cool-temperate water-skink, highland water skink, or Dreeite water skink is a medium-sized species of skink that is endemic to Australia. These skinks are found in New South Wales, South Australia, Victoria as well as on Tasmania's Rodondo Island in the Bass Strait. They are viviparous, mating in spring, and giving birth to live young in mid to late summer.

<i>Eulamprus quoyii</i> Species of lizard

Eulamprus quoyii, more commonly known as the eastern water skink, eastern water-skink, or golden water skink, is a viviparous species of diurnal skink. Eulamprus quoyii belongs to the family Scincidae and is considered a common garden animal in Australia. The skink is endemic to Australia and found only along the east coast of the country. It makes its home in creekside habitats along the east coast of Australia and in urban garden areas with high amounts of moisture. The species can be identified by the twin, long yellow stripes that run along its body from the top of the eye, as well as by several more specific character derived states. The pale yellow dorsolateral stripes are most likely where its common name, the golden water skink, is derived. Like other ectotherms, the skink can often be seen basking in the sun on rocky outcroppings in order to regulate its body temperature. Its diet mainly consists of both aquatic and terrestrial insects, tadpoles and small amounts of plant matter. The skink both hunts for food and scavenges when necessary and is considered an opportunistic feeder. It is prey to larger lizards, snakes, cats and birds and so will often be seen moving quickly into hiding when other organisms are present.

<i>Tiliqua gigas</i> Species of lizard

The Indonesian blue-tongued skink is a lizard in the family Scincidae. It is a close relative of the eastern blue-tongued lizard. They are endemic to the island of New Guinea and other various surrounding islands. They are found typically in the rainforest, and in captivity, require high humidity. In comparison to Tiliqua scincoides, they are fairly lean. They also have long tails.

<i>Cryptoblepharus egeriae</i> Species of reptile

Cryptoblepharus egeriae, also known commonly as the blue-tailed shinning-skink, the Christmas Island blue-tailed shinning-skink, and the Christmas Island blue-tailed skink, is a species of lizard in the family Scincidae that was once endemic to Christmas Island. The Christmas Island blue-tailed skink was discovered in 1888. It was formerly the most abundant reptile on the island, and occurred in high numbers particularly near the human settlement. However, the Christmas Island blue-tailed skink began to decline sharply outwardly from the human settlement by the early 1990s, which coincided with the introduction of a predatory snake and also followed the introduction of the yellow crazy ant in the mid-1980s. By 2006, the Christmas Island blue-tailed skink was on the endangered animals list, and by 2010 the Christmas Island blue-tailed skink was extinct in the wild. From 2009 to 2010, Parks Australia and Taronga Zoo started a captive breeding program, which has prevented total extinction of the species.

<i>Tiliqua scincoides</i> Species of lizard

Tiliqua scincoides is a species of skink. It is native to Australia as well Tanimbar Island.

<span class="mw-page-title-main">Centralian blue-tongued skink</span> Species of lizard

The Centralian blue-tongued skink or Centralian blue-tongue is a species of skink, occurring predominantly in the far north-west corner of New South Wales, Australia. It is one of six species belonging to the genus Tiliqua; the blue-tongued skinks and the shinglebacks.

<span class="mw-page-title-main">Stokes's skink</span> Species of lizard

Egernia stokesii is a gregarious species of lizard of the Scincidae family. This diurnal species is endemic to Australia, and is also known as the Gidgee skink, spiny-tailed skink, Stokes's skink and Stokes's egernia. The species forms stable, long-term social aggregations, much like the social groups seen in mammalian and avian species. This characteristic is rarely found in the Squamata order, but is widespread within the Australian subfamily of Egerniinae skinks. Populations of E. stokesii are widely distributed, but fragmented, and occur in semi-arid environments. There are three recognised subspecies. The conservation status for the species is listed as least concern, however, one subspecies is listed as endangered.

The saltbush slender bluetongue is a species of lizard in the family Scincidae. The species is endemic to the arid interior of eastern Australia. Although its conservation status is of least concern, it has been listed as endangered in New South Wales. The slender saltbush bluetongue has been recorded in Sturt National Park in New South Wales but extends into northeast South Australia and south-west Queensland.

<i>Cryptoblepharus buchananii</i> Species of lizard

Cryptoblepharus buchananii, also known as Buchanan's snake-eyed skink, is a species of lizard in the family Scincidae. The species is endemic to Western Australia.

The Spinifex slender blue-tongue or Samphire slender bluetongue is an endemic species of skink that inhabits the arid areas of central Australia. The Spinifex slender blue-tongue is closely related to the large blue-tongue skinks. However is individually categorised under the Genus Cyclodomorphus and species Cyclodomorphus melanops(C. melanops).

References

  1. 1 2 Tiliqua scincoides at the Reptarium.cz Reptile Database
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Australian Museum 2000.
  3. Abbate, F.; Latella, G.; Montalbano, G.; Guerrera, M. C.; Germanà, G. P.; Levanti, M. B. (October 2009). "The lingual dorsal surface of the blue-tongue skink (Tiliqua scincoides)". Anatomia, Histologia, Embryologia. 38 (5): 348–350. doi:10.1111/j.1439-0264.2009.00952.x. ISSN   1439-0264. PMID   19769569. S2CID   24711884.
  4. 1 2 3 4 5 6 7 8 9 10 Jirik 2021.
  5. 1 2 3 4 5 6 7 8 9 Abbey 2000.
  6. Abramjan, Andran; Bauerová, Anna; Somerová, Barbora; Frynta, Daniel (August 2015). "Why is the tongue of blue-tongued skinks blue? Reflectance of lingual surface and its consequences for visual perception by conspecifics and predators". Die Naturwissenschaften. 102 (7–8): 42. Bibcode:2015SciNa.102...42A. doi:10.1007/s00114-015-1293-4. ISSN   1432-1904. PMID   26185113. S2CID   16915899.
  7. 1 2 3 4 5 6 7 Potter Park Zoo 2017.
  8. 1 2 Myhre & Hammel 1969.
  9. "Eastern Blue-tongued Skink (Tiliqua scincoides) Fact Sheet: Population & Conservation Status". San Diego Zoo Wildlife Alliance Library.
  10. 1 2 3 4 Szabo et al. 2019.
  11. Shea, Glenn M. (1993-01-01). "The male reproductive cycle of the Eastern Blue-tongued Lizard Tiliqua scincoides scincoides (Squamata: Scincidae)". Herpetology in Australia. pp. 397–403. doi:10.7882/RZSNSW.1993.063. ISBN   0-9599951-8-8.
  12. "Eastern Blue-tongue Lizard". The Australian Museum. Retrieved 2021-10-21.
  13. Phillips, C. A.; Roffey, J. B.; Hall, E.; Johnson, Rsp (July 2016). "Sex identification in the eastern blue-tongued lizard (Tiliqua scincoides White, ex Shaw, 1790) using morphometrics". Australian Veterinary Journal. 94 (7): 256–259. doi:10.1111/avj.12429. ISSN   1751-0813. PMID   27349886.
  14. Lambert, Helen; Carder, Gemma; D’Cruze, Neil (2019-10-17). "Given the Cold Shoulder: A Review of the Scientific Literature for Evidence of Reptile Sentience". Animals. 9 (10): 821. doi: 10.3390/ani9100821 . ISSN   2076-2615. PMC   6827095 . PMID   31627409.
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  16. 1 2 Kratzing 1975.

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