Reptiles
Skink
Scincidae · also called skink lizard
Turn over a log or a flat stone in a warm garden and a smooth, glossy lizard may pour out of the gap and vanish. That is very likely a skink — the sleek, streamlined, wedge-headed lizard that makes up one of the two biggest lizard families and that, over and over, has evolved its way toward becoming a snake.
Overview
Skinks are the family Scincidae, around 1,700 species, second in size only to the geckos. The typical skink has smooth, tight scales, a cylindrical body, short legs, a tapering tail, and a wedge-shaped head that blends into the neck — a shape for slipping through grass, litter, and loose soil. Most eat insects and other small invertebrates, though the big blue-tongues are omnivores.
Toward a legless body
Many separate skink lineages have reduced or lost their legs and taken up burrowing, from the sand-swimming sandfish to the various snake-skinks with tiny useless limbs. Most skinks also drop the tail to escape, and young skinks often have a bright blue or pink tail that draws a predator’s strike away from the body.
Unusual families
A few Australian skinks in the genus Egernia live in stable family groups, recognise their relatives, and share a crevice for years — very rare among lizards. And the blue-tongued skink’s startling cobalt tongue is a pure bluff, a flash of colour to make a predator hesitate.
Status
Skinks as a family are Not Evaluated. Most are common, but many island and narrow-range species have declined or gone extinct after rats and cats arrived, and several are Critically Endangered.
Skink: common questions
What makes a lizard a skink rather than another kind of lizard?
Skinks are recognised by a combination of features rather than one single trait. The classic skink look is a smooth, shiny, streamlined lizard with small, flat, closely overlapping scales that often have tiny bony plates beneath them, short legs, a long tail that tapers to a fine point, and a narrow, wedge-shaped head that blends into the neck without an obvious neck constriction. Most skinks also have a transparent lower eyelid or a fixed clear window in the eyelid. They move with a smooth, almost snake-like glide, using body undulation as much as their legs. Not every skink fits every point, since the family is huge and varied, but that overall impression separates a skink from a rough-scaled agamid, a warty gecko, or a long-legged wall lizard.
Why have so many skinks lost their legs?
Because for an animal that lives by burrowing or by pushing through dense grass and litter, legs get in the way. In loose sand or soil, a smooth, cylindrical, legless body driven by side-to-side waves moves more efficiently than one that has to fold and swing limbs, and the skink family, with its already elongated, low-slung shape, is unusually prone to going the whole way. Evolutionary studies show limb reduction and loss has happened dozens of times independently within the skinks, in Australia, Africa, and elsewhere, producing a full range of forms from four normal legs, through progressively shorter legs and fewer toes, to tiny scaly flaps and finally nothing at all, essentially a lizard that has become a small burrowing snake.
Are skinks good pets, and are they dangerous?
Several skinks are popular, well-behaved pets, most of all the blue-tongued skinks of Australia and New Guinea, which are large, calm, long-lived, and become genuinely tame, and the smaller fire skinks and other African species. None is dangerous. A big skink can give a firm, briefly painful bite if it is grabbed or mishandled, and the blue-tongue in particular has strong jaws for crushing snails, but there is no venom and no lasting harm. Skinks kept as pets should be captive-bred rather than wild-caught, given a warm basking area and a cooler retreat, and, for the omnivorous species, a varied diet rather than just insects or just greens.
Where do skinks live, and might I see one in my garden?
Skinks are among the most widespread lizards, and depending on where you are, a garden skink may be a regular sight. In much of Australia, small striped garden skinks bask on paths and walls and dart under leaf litter all summer. In the south-eastern United States, five-lined and broad-headed skinks live around wood piles, sheds, and gardens. In Europe there are fewer species and they are more local, but skinks occur around the Mediterranean. Elsewhere, tropical gardens across Africa and Asia usually hold several skink species. They favour warm, sunny spots with cover close by, such as rockeries, log piles, compost heaps, and the base of walls, and they retreat instantly into a crevice at any disturbance.