Skinks are reptiles characterized by long, cylindrical bodies and tapering tails. They belong to the lizard family Scincidae, which is part of the reptilian order Squamata, a group that includes snakes and other lizards. Unlike true lizards from the family Lacertidae, skinks have relatively shorter necks and legs.
They are found in almost every habitat except the Arctic and sub-Arctic regions. These reptiles are typically insectivorous, but some consume a variety of fruits, vegetables, and even moss.
There are over 1,500 described skink species classified under seven subfamilies and around 170 genera.
Though most skinks measure around 4.5 in (12 cm) in snout-to-vent length, the largest species, the Solomon Islands skink (Corucia zebrata), is 14 in (35 cm) long. In contrast, some of the smaller species, such as Scincella lateralis, range between 3 to 5.7 in (7.5 to 14.5 cm) in length.
Skinks usually have a cylindrical body, a cone-shaped head, and a long, tapering tail. Although they resemble true lizards in appearance, they lack a pronounced neck and have considerably smaller limbs. However, some species, like the red-eyed crocodile skink, have a distinct neck that distinguishes the head from the rest of the body. Some genera, like Neoseps, have such reduced limbs and fewer toes that they almost look like snakes while moving.
They have hard skulls covered by overlapping bony scales, providing extra protection and structural support.
These reptiles derive their name from the Greek word skinkos and the Latin word scincus. Currently, over 1,500 extant species are grouped under 7 subfamilies and around 170 genera.
In addition, some extinct fossil genera include Aethesia, Orthrioscincus, Sauriscus, Aocnodromeus, and Ayalasaurus. However, some genera, like Mabuya, are not well-studied, and thus their systematic position remains controversial.
The earliest known skink, Electroscincus zedi, was unearthed from Burmese amber in Myanmar. It dates back to the Middle Cretaceous Period (around 100 million years ago). The presence of bony deposits called osteoderms on its body suggests that it may represent the crown group of skinks. Other undisputed skink fossils belong to the Miocene Epoch.
These reptiles are found almost everywhere (cosmopolitan) except in the Arctic and Sub-Arctic regions. They are particularly diverse in the temperate regions of North America, Australia, and Southeast Asia.
Sand skinks (genus Scincus) are native to North Africa and Asia, while keeled skinks (genus Tropidophorus) are found in Southeast Asia, extending all the way to Australia. Members of the genera Mabuya and Cryptoblepharus are distributed across the tropics, while those in the genus Plestiodon are most abundant in the temperate regions of the New World, including Japan.
Being mostly terrestrial and a few aquatic, skinks typically inhabit a wide variety of habitats, such as grasslands, rainforests, mountains, deserts, and mangroves. Most terrestrial skinks live in burrows (fossorial) than in trees.
Skinks are typically carnivorous and feed on a wide range of insects, like crickets, flies, beetles, grasshoppers, and even caterpillars. They also consume other invertebrates, such as arachnids, centipedes, millipedes, earthworms, and mollusks. Among vertebrates, they feed on other lizards (like geckos) and small rodents.
In captivity, many skinks feed on leaves, flowers, fruits, and vegetables. Again, members of the genus Tristiidon are primarily fruit-eaters (frugivorous) and are sometimes even found to feed on mosses.
Skinks are diurnal and are found to bask on rocks or tree logs during the daytime. However, they spend most of their time hiding in burrows or digging out tunnels to prevent meeting a predator’s eye, a characteristic feature common in skinks.
These lizards flick their tongues and pick up scent particles from the air. These particles then enter the mouth and land on specialized sensory cells called Jacobson’s organs. Using such a mechanism, these reptiles also sense their prey and chase them down. Once the prey has surrendered, they bite and swallow it whole. However, skinks lack venom and are non-poisonous; thus, their bites are minor and non-lethal to humans.
When under a predator’s grip, skinks, like many other lizards, often shed their tails quickly to free themselves, a phenomenon known as autotomy. In about three to four months, they slowly regenerate their lost tails.
They are territorial and often stand in front of their nests, religiously guarding the eggs within. When an intruder is around, they hiss and puff up their bodies to appear intimidating.
Their life expectancy varies greatly among different species. While some, like common garden skinks, live for 2 to 3 years, others, like Northern blue-tongued skinks, survive up to 20 years in captivity.
Around the breeding season, when the level of testosterone is high in male skinks, their heads turn red, and the head muscles increase in size. They slowly become aggressive to other males and engage in courtship behaviors to attract potential mates. These attempts include the release of chemical signals to draw the attention of females. In fact, the males can distinguish between receptive and non-receptive females by detecting scents through their Jacobson’s organs.
Once the pair establishes, they copulate and later seek grounds to build nests for laying eggs. They typically select habitats such as underneath thick foliage or even man-made spaces like basement garages and first-floor apartments that are less frequented by potential predators.
Though most skinks are oviparous and lay eggs in clutches of 4 to 8 at a time, about 45% are viviparous and give birth to live young. Some skinks, however, are ovoviviparous, with the eggs developing and hatching within the mother’s reproductive tract.
In members of the genera Tiliqua and Corucia, the developing young are nourished within the mother’s body by a mammal-like placenta (matrotrophy). In the species Trachylepis ivensi, the placenta is as complex as that found in eutherian mammals.
The young emerge from the eggs as hatchlings (also called skinklets) and gradually grow into adults. While some attain sexual maturity within a year, others may take several years to mature.
Skinks are preyed upon by a variety of animals, including foxes, raccoons, weasels, cats, dogs, herons, hawks, rodents, and other reptiles such as snakes and lizards. Some species, like the Anguilla Bank skink (Spondylurus powelli), face significant threats from predators like mongooses, which have nearly driven them to extinction.
Moreover, some indigenous people in New Guinea and Papua New Guinea hunt and consume these animals.
Skinks that typically burrow underground have a transparent scale covering their eyes, which protects them from debris. This replaces the movable lower eyelid found in other burrowing species.
Skinks of the genus Prasinohaema have green blood due to the buildup of biliverdin, a green bile pigment that accumulates as a waste product in their bodies.
Welcome to AnimalFact - your go-to source for fascinating insights into the amazing world of animals!
