I was probably about ten years old when I saw my first legless lizard. I was fishing with my dad and his friend, who happened to be a biologist. We came upon what I thought was a snake. But my dad's friend pointed out that it was actually a "slender glass lizard," a type of lizard without legs. This blew my mind! A long, skinny reptile without legs had to be a snake, right? Nope, not necessarily. Consequently, I've been fascinated by legless lizards ever since then. Below is a slender glass lizard, the same kind I saw that day fifty years ago.
What the heck is a Legless Lizard?
Actually, the term legless lizard is used to refer to a variety of different types of lizards that have lost their legs over time. In different areas of the world, these different groups have lost their legs independently of each other and are not closely related.
Amazingly, at least SEVEN different families of lizards have evolved legless species independently! This includes hundreds of species of legless lizards around the world.
The first question people often have is, why don't we just call these creatures snakes? Well, because they aren't snakes. Other than being legless, these creatures do not have the characteristics of snakes. Legless lizards have eyelids, snakes do not. Legless lizards have external ears, snakes do not. Legless lizards do not have wide belly scales, snake do. Legless lizards have short bodies and long tails, snakes have long bodies and short tails.
Not confusing at all, right? Check out the head of the European glass lizard below (this species also has the awesome name scheltopusik). You can see the lizard's eyelids, which allows it to close its eyes. You can also see its ear openings (behind the mouth). And behind that you can see part of the lateral fold, a weird fold of skin that runs the length of the lizard on each side. Snakes do not have any of these characteristics.
Amazing facts about Legless Lizards
Again, legless lizards are not snakes. They evolved from four-legged lizards, like those we have all seen. Snakes evolved from four-legged snake-like creatures that most of us have never seen (most of those lived long ago).
Legless lizards eat smaller prey than snakes because they cannot "unlock" their jaws. As you probably know, snakes can unhinge their jaws to swallow prey bigger around than their own head. Lizards cannot do this. Legless lizards typically eat insects, snails, spiders, and other small prey that will fit conveniently in their mouth. So, a typical snake will eat just occasionally, swallowing an animal large enough to sustain it for a while. A legless lizard eats small things frequently.
Below is a Burton's legless lizard eating a smaller lizard.
Many legless lizards are called glass lizards. Here's why. You may know some lizards are capable of losing all or a portion of their tail when attacked by a predator. They can then grow the tail back (at least partially). Well, glass lizards are very good at this. Not only do they have a really long tail, but the tail is extremely fragile. In fact, they can even break their tail off by themselves. They can actually thrash around hard enough to break it off without ever being touched. Since that day fifty years ago, I have found perhaps twenty or so slender glass lizards, and almost all of them had broken their tail at some point in their lives. You can easily tell because, once broken, the tail does not grow back the same way as before.
Notice the regenerated tail of the eastern glass lizard below.
This tail-breaking ability is called caudal autotomy (the word autotomy in Greek means "self severing"). This is really an amazing capability—the tail continues wriggling, which distracts the predator's attention from the fleeing lizard. As the lizard gradually regenerates the tail, instead of growing new vertebrae made of bone, the tail usually contains cartilage and is shorter than the original tail. Lizards have special sphincter muscles in the tail that squeeze the caudal artery closed to minimize the amount of bleeding.
Fossils have been found that show caudal autotomy was present in some lizards as long ago as the Jurassic period! Most likely, small lizards were escaping from the clutches of dinosaurs by dropping their tails!
Check out this video by Jungle Bob on legless lizards.
Okay, one last thing... WHY? Why have so many species of lizards evolved to have no legs? Wouldn't they be better off with legs? Well, first of all, we have to recognize that the long, slithery, legless lifestyle must be a pretty good one. Otherwise, snakes and legless lizards wouldn't be so abundant. It also helps to consider that creatures living underground may be better off without legs (think about worms).
So, it's quite possible legless lizards evolved as some types of lizards started living in the soil. As they became more and more adapted to life in the soil, they gradually lost their legs. Then, later, some of those started living above ground again, but by that time they had already lost their legs. Makes perfect sense, right?
To make things even more confusing, there are some snakes that still have remnants of legs (boas and pythons are examples), and there are some legless lizards that have legs! Legless lizards in the family Pygopodidae don't have forelimbs, but they have small remnants of hind legs.
Make up your mind, why don't you! Legs or no legs?
Hmm... whoever came up with the phrase "Leaping lizards!" probably wasn't thinking about legless lizards. I just thought I'd toss that thought into the mix. You're welcome.
So, Legless Lizards deserve a place in the J.D.A.H.O.F.
(Jim-Dandy Animal Hall of Fame).
FUN FACT: The term jim-dandy was first used in the Courier-Journal newspaper in Louisville, Kentucky in 1887: "Dear Sir: Though a stranger to you (yet a Democrat), let me say you are a 'Jim Dandy.'" This term can be both a noun (as used above) and an adjective. As a noun, it means something that is "a superior example of its kind." As an adjective, it means excellent or outstanding. Etymologists are not sure if the term ever referred to an actual person. But there was a popular minstrel song in the 1840s called "Dandy Jim of Caroline." Perhaps that's what gave people the idea of using the phrase? The word dandy dates back to the late 1700s, and it referred to a young man "who devotes excessive attention to fashionable dress and grooming." Anyway, jim-dandy is another way to say awesome!
Baby elephant trunk - Imgur
Sloth - finstad4
Slender glass lizard - Todd Pierson, Herps of NC
European glass lizard head - Australian Reptile Park
Burton's Legless lizard eating a skink - Luke Jongens/Flickr
Eastern glass lizard with regenerated tail - Pinterest
Legless lizard lifting its head - San Diego Zoo
Everyone needs a creative outlet. That's why I write.