Eastern blue-tongued skink

Appearance

The eastern blue-tongued lizard has a short body and short legs. This lizard weighs approximately 1 kilogram and extends approximately 60 centimeters. 36 cm of the 60 cm are the lizards' head and body. 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. In other words, the length of the hind legs is roughly 62 mm while the tail length is approximately 195mm and makes up 50-75% of the snout-vent length.

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. This blue tongue is used to alarm predators and scare them off. The eastern blue-tongued lizard has smooth skin covered with scales that overlap and have small bone plates. The ventral 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. Across its body, the eastern blue-tongued lizard has broad black and brown bands. This lizard can generally be identified by the black stripe that extends from its eye to the tympanum , and sometimes all the way to the side of the neck. Their blue tongues could be an evolutionary adaptation that assists in long-distance communication in order to warn off predators and decrease aggressive activity.

Status

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

Cane toads have become an invasive species in Australia which affect all native predators, including blue-tongued skinks. These lizards are killed by these toxic toads, thus affecting their population.

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.

Behavior

''Tiliqua scincoides scincoides'' show very little aggression and are said to be docile and shy. 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 them off by showing that it may be distasteful. The lizards also hiss, inflate and lunge, which may evoke fear in any potential predator.

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 eastern blue-tongued lizard.

Studies have shown that reptiles are capable of displaying human-like feelings, such as anxiety and pleasure among other emotions.

Habitat

''Tiliqua scincoides scincoides'' are found in the coastal plain and lower Blue Mountains near Sydney, Australia and in the majority of New South Wales. Eastern blue-tongues frequent open country and take shelter among large objects on the ground like logs or rocks or among leaf litter. 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 and 35 degrees Celsius when they are active. 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 when the sun is out, so that they can bask in the sun. They infrequently leave the comfort of their hollow logs and ground debris.

Reproduction

The eastern blue tongue becomes sexually mature between 561 and 590 days. ''T. s. 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. Female lizards give birth to 6-20 young per year. Similar to other animals, these offspring are nourished by the primitive placenta.

''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. This study highlights the idea that ''T. s. 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.

Interestingly, research has shown that sexual maturity occurs at different body sizes depending on the location where a male ''T. s. scincoides'' resides. For example, it was found that sexual maturity happens at smaller body sizes in the southern part of Australia than in Queensland.

Food

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 contains extra minerals and vitamins.  These lizards eat during the day and have been labeled as diurnal. 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. When feeding, the lizard will use their extensive, wet adhesion tongue to capture the prey , similar to Iguania, before transporting it into their mouths. These lizards also eat crickets and wax worms.Species of reptile native to Australia

Predators

Blue tongues fall prey to large snakes and large predatory birds. The large snakes include the mulga snake , the red bellied black snake, the black-headed python , and the eastern brown snake The large predatory birds include the laughing kookaburras and brown falcons. 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.

Defense

''Tiliqua scincoides scincoides'' are not venomous or deadly to humans. Bites from this skink will cause pain and leave a bruise; however, they will not cause any long-term effects.