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5 Slithering Differences Between Snakes and Legless Lizards

Ceci n'est pas un serpent. It's a glass lizard. Image credit: Don Becker via Wikimedia Commons // CC BY-SA 3.0

 
If a limbless reptile like the one above crosses your path, it’s obviously a snake, right? Maybe not. Over the course of evolution, many different lizards have independently lost their legs. Today, we’re looking at the subtle differences that set these creatures apart from their serpentine brethren.

1. WE’VE YET TO FIND A LEGLESS LIZARD WITH A FORKED TONGUE.

All snakes have such tongues—as do a fair number of lizards, including gila monsters, monitor lizards (such as the Komodo dragon), and South American tegus. When it comes to tracking down food, these pronged organs are incredibly useful. Here’s how they work: Wandering animals leave microscopic taste particles floating behind them in the air. Snakes and some lizards gather these up by flicking their forked tongues. After the tongue is drawn back into the mouth, the chemicals are delivered to a sensory apparatus called the vomeronasal organs. These help the reptiles figure out what sort of creature produced the taste particles in question. Although legless lizards are a diverse bunch, none that we know of feature this kind of tongue.

2. SNAKES DON’T HAVE EYELIDS, BUT SOME LEGLESS LIZARDS DO.

Snakes can’t blink (or wink, for that matter). Unlike us, the slithering reptiles don’t possess eyelids. Evolution’s given them a different way to protect their invaluable pupils. In the vast majority of species, a thin, transparent scale covers each eye. These are known as “spectacles” or “brilles” and, like most scales, they’re regularly replaced when the snake sheds its skin.

Numerous lizards—including most geckos—also have brilles instead of eyelids. However, many legless species sport the latter. For example, consider the so-called “glass lizards.” A widespread group, these lithe creatures can be found in Morocco, North America, and parts of Asia. Like snakes, glass lizards are essentially devoid of legs: Their forelimbs are completely gone while their rear legs have evolved into useless nubs that lie buried under the skin. Yet, unlike snakes, glass lizards do possess moveable eyelids.

3. NO KNOWN SNAKE HAS EXTERNAL EAR HOLES.

It’s often said that snakes are deaf. Over the past few decades, research has thoroughly disproved this notion, and we now know that the animals can easily detect certain airborne sounds. So where did the whole myth about snakes not being able to hear come from? Well, the misconception probably has something to do with the fact that snakes don’t have visible ear openings.

Most land vertebrates have both an eardrum and an inner ear. Snakes, on the other hand, lack the former. Their inner ears are connected directly to the jawbones, which usually rest against the ground. Whenever some other animal walks by, its footsteps inevitably produce vibrations. These travel through the earth and cause the snake’s jaw to vibrate in response. The inner ear then signals the brain, which interprets the data and identifies the source of the sound. Low-frequency noises that travel through the air can also be picked up in more or less the same manner.

Look closely at a snake, and you’ll notice that there aren’t any ear holes on the sides of its head. In contrast, most legless lizards have a pair. Then again, some varieties don’t. The Australian Aprasia lizards are adapted for a burrowing lifestyle—one that doesn’t really require external ear cavities. As such, most members of this genus lack these openings altogether.

4. SNAKE JAWS TEND TO BE A LOT MORE FLEXIBLE.

A lora, or parrot snake, eats an evergreen robber frog in Panama. Image credit: Brian Gatwicke via Wikimedia Commons // CC BY 2.0


 
Contrary to popular belief, snakes don’t unhinge or dislocate their jaws while feeding. They simply don’t need to. An average snake can swallow prey that are several times larger than its own head. This feat is made possible by an amazingly flexible set of jaws.

Just like in humans, a snake’s lower jaw consists of two bones called mandibles. Ours meet to form a chin, which is where the separate bones become fused. Snake mandibles aren’t joined together in this manner. Instead, the two lower jawbones can move independently of each other and can even splay apart to a considerable extent.

By comparison, the jaws of most legless lizards are far less maneuverable. As a result, they tend to eat proportionally smaller prey—but there’s an exception to this rule. Burton’s snake lizard (Lialis burtonis) is an unusual predator that specializes in eating other lizards. Bisecting the skull is a special hinge which enables the front of its snout to swing downwards. This gives Burton’s snake lizard enough oral flexibility to swallow fairly big prey whole. Recurved teeth and a muscular tongue help prevent the prey from escaping.

5. WHEN THREATENED, MANY LEGLESS LIZARDS CAN DISCARD AND RE-GROW THEIR TAILS.

If a snake, crocodilian, turtle, or tortoise loses its tail, the animal won’t be able to replace it with a new one. In the world of reptiles, that talent is reserved for lizards. Many—but not all—lizard species can famously lose a segment of their tail and then regenerate it (although the replacement is not as good as the original). This is no parlor trick: Out in the wild, it’s a potentially life-saving maneuver. Should a predator seize a lizard by the tail, the whole appendage can break off. Afterward, this discarded appendage might flail and spasm, distracting the attacker long enough for our lizard to escape. Check out some graphic images of a glass lizard sans tail.

There’s a correlation between a legless lizard’s habitat and the length of its tail. Species that burrow through dirt or spend most of their time submerged in sand have relatively short tails. In contrast, those that live at the surface have rather long ones. Why is this? To lizards with subterranean habits, lengthy tails can be a nuisance because they create excessive drag during digs. Up above the soil, however, a really long tail reduces the odds of some predator snagging a more vital part of the body.

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Everything You Ever Wanted to Know About Dogs
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Dogs: They’re cute, they’re cuddly … and they can smell fear!

Today on Scatterbrained, John Green and friends go beyond the floof to reveal some fascinating facts about our canine pals—including the story of one Bloodhound who helped track down 600 criminals during his lifetime. (Move over, McGruff.) They’re also looking at the name origins of some of your favorite dog breeds, going behind the scenes of the Puppy Bowl, and dishing the details on how a breed gets to compete at the Westminster Kennel Club Dog Show.

You can watch the full episode below.

For more episodes like this one, be sure to subscribe here!

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Sploot 101: 12 Animal Slang Words Every Pet Parent Should Know
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For centuries, dogs were dogs and cats were cats. They did things like bark and drink water and lay down—actions that pet parents didn’t need a translator to understand.

Then the internet arrived. Scroll through the countless Facebook groups and Twitter accounts dedicated to sharing cute animal pictures and you’ll quickly see that dogs don’t have snouts, they have snoots, and cats come in a colorful assortment of shapes and sizes ranging from smol to floof.

Pet meme language has been around long enough to start leaking into everyday conversation. If you're a pet owner (or lover) who doesn’t want to be out of the loop, here are the terms you need to know.

1. SPLOOT

You know your pet is fully relaxed when they’re doing a sploot. Like a split but for the whole body, a sploot occurs when a dog or cat stretches so their bellies are flat on the ground and their back legs are pointing behind them. The amusing pose may be a way for them to take advantage of the cool ground on a hot day, or just to feel a satisfying stretch in their hip flexors. Corgis are famous for the sploot, but any quadruped can do it if they’re flexible enough.

2. DERP

Person holding Marnie the dog.
Emma McIntyre, Getty Images for ASPCA

Unlike most items on this list, the word derp isn’t limited to cats and dogs. It can also be a stand-in for such expressions of stupidity as “duh” or “dur.” In recent years the term has become associated with clumsy, clueless, or silly-looking cats and dogs. A pet with a tongue perpetually hanging out of its mouth, like Marnie or Lil Bub, is textbook derpy.

3. BLEP

Cat laying on desk chair.
PoppetCloset, Flickr // CC BY-NC-ND 2.0

If you’ve ever caught a cat or dog poking the tip of its tongue past its front teeth, you’ve seen a blep in action. Unlike a derpy tongue, a blep is subtle and often gone as quickly as it appears. Animal experts aren’t entirely sure why pets blep, but in cats it may have something to do with the Flehmen response, in which they use their tongues to “smell” the air.

4. MLEM

Mlems and bleps, though very closely related, aren’t exactly the same. While blep is a passive state of being, mlem is active. It’s what happens when a pet flicks its tongue in and out of its mouth, whether to slurp up water, taste food, or just lick the air in a derpy fashion. Dogs and cats do it, of course, but reptiles have also been known to mlem.

5. FLOOF

Very fluffy cat.
J. Sibiga Photography, Flickr // CC BY-NC-ND 2.0

Some pets barely have any fur, and others have coats so voluminous that hair appears to make up most of their bodyweight. Dogs and cats in the latter group are known as floofs. Floofy animals will famously leave a wake of fur wherever they sit and can squeeze through tight spaces despite their enormous mass. Samoyeds, Pomeranians, and Persian cats are all prime examples of floofs.

6. BORK

Dog outside barking.
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According to some corners of the internet, dogs don’t bark, they bork. Listen carefully next time you’re around a vocal doggo and you won’t be able to unhear it.

7. DOGGO

Shiba inu smiling up at the camera.
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Speaking of doggos: This word isn’t hard to decode. Every dog—regardless of size, floofiness, or derpiness—can be a doggo. If you’re willing to get creative, the word can even be applied to non-dog animals like fennec foxes (special doggos) or seals (water doggos). The usage of doggo saw a spike in 2016 thanks to the internet and by the end of 2017 it was listed as one of Merriam-Webster’s “Words We’re Watching.”

8. SMOL

Tiny kitten in grass.
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Some pets are so adorably, unbearably tiny that using proper English to describe them just doesn’t cut it. Not every small pet is smol: To earn the label, a cat or dog (or kitten or puppy) must excel in both the tiny and cute departments. A pet that’s truly smol is likely to induce excited squees from everyone around it.

9. PUPPER

Hands holding a puppy.
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Like doggo, pupper is self-explanatory: It can be used in place of the word puppy, but if you want to use it to describe a fully-grown doggo who’s particularly smol and cute, you can probably get away with it.

10. BOOF

We’ve already established that doggos go bork, but that’s not the only sound they make. A low, deep bark—perhaps from a dog that can’t decide if it wants to expend its energy on a full bark—is best described as a boof. Consider a boof a warning bark before the real thing.

11. SNOOT

Dog noses poking out beneath blanket.
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Snoot was already a dictionary-official synonym for nose by the time dog meme culture took the internet by storm. But while snoot is rarely used to describe human faces today, it’s quickly becoming the preferred term for pet snouts. There’s even a wholesome viral challenge dedicated to dogs poking their snoots through their owners' hands.

12. BOOP

Have you ever seen a dog snoot so cute you just had to reach out and tap it? And when you did, was your action accompanied by an involuntary “boop” sound? This urge is so universal that boop is now its own verb. Humans aren’t the only ones who can boop: Search the word on YouTube and treat yourself to hours of dogs, cats, and other animals exchanging the love tap.

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