Skinks have adopted a wide variety of habits. Most are diurnal, but others, such as some species of Egernia and Eremi-ascincus, are nocturnal. Many North American skinks, especially Eumeces, are secretive, spending much of their time under fallen logs or rocks; thus, they are not very conspicuous. Central and South American skinks (Mabuya and Sphe-nomorphus) are active during the day and frequently are observed basking or foraging. In some parts of Africa and Australia, skinks are very conspicuous and diverse, being active during the heat of midday, often in very arid areas.
Almost all skinks exploit tail autotomy as a means of escape from predators, although a few skinks, such as some species of Egernia, Corucia, and Tiliqua, do not shed their tails. Some Egernia species have flattened, spiny tails, which are used to block off entrances to their crevice retreats. Australian Ctenotus and North American Scincella sometimes return to the site where their tails were lost and swallow the remains of them. Few, if any, other vertebrates display auto-amputation and self-cannibalism.
Visual cues are used in individual discrimination, particularly the choice of mate, as well as in prey discrimination. Skinks have exceedingly well developed olfactory abilities and can recognize and determine species, sex, and sexual receptivity of other individuals by scent. They also can detect predators and discriminate prey on the basis of chemical cues.
All skinks possess bony plates within their scales, known as osteoderms, which are composed of compound plates of several interconnected bones underneath each scale. Scales overlap in the fashion of shingles on a roof. Such body armor doubtless confers protection from predators. One pygopodid lizard and several species of snakes have evolved hinged teeth to facilitate obtaining a firm grip on their skink prey. (Hinged teeth fold when they hit an osteoderm.) Indeed, if a skink struggles backward during ingestion, the teeth lock into place. Skinks are swallowed rapidly, suggesting that they might actually facilitate their own ingestion, crawling away from the ratchet-like teeth down a predator's gullet. Some skinks have very loose skin and scales that tear away when they are attacked by predators, allowing for escape.
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