Reptiles
Alligator Lizard
Elgaria · also called alligator lizards
An alligator lizard looks like it is built from two different lizards stitched together: a stiff, armoured back and a soft, stretchy fold of skin down each side that lets its body swell after a big meal without a single scale cracking. Grab one and it will usually bite first and think about it later, though the bite is harmless and the lizard typically calms down fast.
Overview
Alligator lizards, genus Elgaria, are long-bodied, short-legged lizards found across western North America, from forest and grassland to mountain slopes and suburban gardens. They hunt insects, slugs, and small animals during the day, with a slow, sinuous, almost snake-like way of moving through leaf litter.
Built to stretch, built to snap off a tail
The flexible lateral skin fold along each side lets the body expand for a big meal or a clutch of eggs. Depending on climate, different species either lay eggs or give birth to live young, and like many lizards, a grabbed tail — often longer than the body itself — detaches and keeps thrashing while the lizard escapes.
Status
Least Concern — widespread and common, tolerating gardens, woodpiles, and other human-altered habitat well across much of its western North American range.
Alligator Lizard: common questions
Why does an alligator lizard have a fold of skin along its sides?
The lateral skin fold running along each side of the body is more flexible and less rigidly scaled than the rest of the lizard's armoured skin, and it can stretch outward to accommodate an unusually large meal, a clutch of developing eggs, or general seasonal weight gain without the more rigid dorsal scales having to stretch or split. This gives the alligator lizard a degree of flexibility in body volume that a uniformly rigid, tightly scaled body would not easily allow.
Is an alligator lizard dangerous to handle?
No, an alligator lizard is not dangerous to humans, though it will often bite firmly if picked up and may release a foul-smelling musk from glands near the tail base as a defensive deterrent, both of which can be startling but cause no real harm. Most individuals settle down noticeably after a short period of gentle, regular handling, and the bite itself, while it can pinch, is not capable of causing serious injury to a person.
Why do some alligator lizards lay eggs while others give birth to live young?
Species and populations living in cooler climates or at higher elevations, where consistently warm conditions needed for successful egg incubation in the ground are less reliable, have generally evolved to give birth to live young instead, allowing the mother to regulate her own body temperature through basking and protect developing embryos far more effectively than eggs left in cool soil could be protected. Species from warmer, lower-elevation habitats, by contrast, more commonly retain egg-laying, since ground temperatures there are reliable enough to support normal egg development.
How is an alligator lizard different from a skink?
Although both are smooth-bodied, elongated lizards that can look superficially similar at a glance, alligator lizards belong to a separate family, Anguidae, and are distinguished by their characteristic flexible lateral skin fold along each side of the body, a feature skinks lack entirely. Alligator lizards also tend to have a stiffer, more armoured overall body and a notably long tail relative to body length, while skinks typically have smoother, more uniformly glossy scales without the distinctive expandable side fold that gives alligator lizards their name.