These lizards lost their legs, but don’t call them snakes
An expert explains why legless lizards are the coolest reptiles you’ve never heard of.
By Jason Bittel,
iStock
What do you call a reptile with no legs? If you answered “snake,” you’d be right. But did you know there’s another kind of reptile that fits the same description?
They’re called legless lizards, and they are more common than you might think.
“Legless lizards are normal lizards that lost their legs,” says Chelsea Connor, a herpetologist at Midwestern State University in Texas. (A herpetologist is a scientist who studies reptiles and amphibians.)
Of course, legless lizards didn’t just kick off their legs and slither away one day. Over millions of years, the animals developed smaller and smaller limbs until, eventually, their legs and arms disappeared. This kind of change, which is called evolution, often happens over long periods of time.
Connor explains it this way: Everything about an animal, from its eye color to the length of its tail, is encoded in the animal’s genes. And animals that are better able to find food and mates, and escape from predators, are more likely to pass their genes to their offspring.
“Legless lizards tend to live underground. And it’s a lot easier to sort of swim through the dirt than it is to dig through it,” says Connor. “So for legless lizards, being able to burrow underground faster is a desirable trait.”
Emily Fyfe/Jacksonville Zoo
The Eastern glass lizard, also legless, can be seen at the Jacksonville Zoo. One of the noticeable differences between lizards and snakes is that lizards can blink but snakes cannot. Snakes have membranes to protect their eyeballs.
This means that a long, long time ago, a lizard was hatched that had shorter than usual legs. And for whatever reason, that little-legged lizard was extra good at surviving. Most important, it was still able to find a mate and pass on its gene mutation (change) for tiny limbs to its offspring. In turn, that first lizard’s offspring must have also survived and passed on their genes, perhaps adding more genes for even shorter legs along the way.
Connor says snakes used to have legs, too. But snakes lost their legs much longer ago. Snakes come from a different branch of the reptile family tree than legless lizards, which is why they aren’t the same. In fact, there are easy-to-recognize differences between legless lizards and snakes.
For example, legless lizards can blink. Snakes don’t have eyelids but instead protect their eyes with see-through membranes. Legless lizards also have tiny ear holes on either side of the head, while snakes lack external ears. Snakes have relatively short tails, says Connor. But legless lizards are mostly tail, with the part of the animal that comes after the internal organs making up as much as two-thirds of a legless lizard’s length.
There are hundreds of legless lizard species found around the world. Some are skinny and super snakelike, while others are chunks,with bulky, legless frames. There are also many species of lizard on their way toward evolving leglessness. These animals, such as the Western three-toed skink or Transvaal grass lizard, still have teeny arms or legs, but those are mostly useless.
Most legless lizards survive on a diet of insects and are harmless to humans. Some people even keep them as pets. It’s also not unheard of to find a legless lizard in a backyard.
“They just kind of chill in the leaf litter and eat pesky insects that might be harming your garden,” says Connor. “Every animal has its place on Earth.”
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