If you see a reptile without legs, you probably think you’re looking at a snake. However, other reptiles and even amphibians have also evolved the same body plan.
Legless lizards can have no legs or vestigial limbs that aren’t used for locomotion. There are seven families of lizards that have separately evolved limblessness.
This covers hundreds of unique species that are not always closely related.
While it is difficult to summarize these species, we can give a few general clues that will help you determine if you are looking at a snake or a legless lizard.
The differences between legless lizards and snakes are:
One of the biggest clues is the presence of ears. If you have ever looked at a lizard, you will notice the hole on the side of the head. This is the opening to the ear of the lizard.
Snakes do not have any external ear structures. They hear primarily via vibrations picked up from the jaw.
They can hear some sounds in the air, but this requires specific volumes and frequencies. They mainly sense sound via vibration.
Most legless lizards have the same auditory structures that limbed lizards have. This is one of the easiest ways to tell them apart at a glance.
Snakes don’t have eyelids. Instead, they have a clear scale over the eyes. This protects the sensitive eye from damage. These scales are also typically adapted to help aid vision during their normal active times.
Diurnal snakes typically have UV protection while nocturnal snakes will typically lack this. Most legless lizards retain the eyelids common in most lizards.
This does depend on the exact family and species. Some have evolved away from having eyelids while others retain them. This means that lacking eyelids doesn’t mean a limbless reptile is a snake.
If it is possible and safe, take a look at the belly of the animal. Snakes have a series of scales on the belly that are typically broad and flat.
Snakes have the ability and the musculature under these scales to use them to cross flat surfaces.
They can also use the muscles along their sides to help them move over a variety of terrains.
Legless lizards do not have flat belly scales.
They typically have an underside like most other lizards out there. Many species of legless lizards use their side muscles to move along the ground. They can struggle when they need to move over a flat surface like a road.
Snakes have uniquely flexible jaws that allow them to consume food larger than their heads.
They can use the separated halves of their jaw to “walk” their head over the prey and force it down their throat.
Legless lizards do not have this adaptation. They typically have the same restrictions in diet that lizards do.
Prey needs to be much smaller than their head or easy to break down.
Snakes have a forked tongue that they use to detect odors in the air.
The two tips of their tongue can spread out and catch odor particles in the air or on a surface. They can then bring the tongue inside their mouth and use the olfactory organ on the roof of their mouth.
Since they have two tips, they can smell in stereo. This ability is useful to find prey and mates for snakes.
Since they use their tongue as a major sensory organ, snakes have a small opening on the front of their face so they do not need to open their mouth to smell.
Legless lizards have tongues like other lizards.
Because of the difference in jaws, snakes and legless lizards have different diets. Snakes are obligate carnivores that consume prey whole.
Snakes can consume everything from insects to mammals. They can eat prey larger than their heads with ease. Most snakes will not eat prey much larger than the widest part of their body.
Legless lizards are restricted to food items smaller than their head. Like other lizards, they can have a wide diet that includes fruit and vegetables. The exact diet will depend on the species.
Even snakes with very long tails have tails that make up under a third of their total length. While it can be hard to tell, you can tell where a snake’s tail starts by looking for the cloaca or vent.
The tail is located below this point. In the primitive snakes like pythons and boas, there is typically a pair of spurs that are the remains of the back limbs.
Inside the body, these snakes retain their pelvis. Legless lizards tend to have long tails that can be up to 2/3 of their total length.
Many legless lizards have the same ability to shed their tails to distract a predator. Snakes cannot drop their tails and losing parts of their tail can seriously harm them.
This is very variable and depends heavily on the exact species. Only the primitive snakes retain a trace of their limbs. All known extant snakes lack their forelimbs.
Members of the python and boa families do retain small remnants of their hindlimbs referred to as spurs. These spurs are only used for mating.
Some legless lizards do lack all limbs, but others may retain small vestigial limbs.
For instance, members of the Pygopodidae family retain small hindlimbs that are useless for moving around.
They are small flaps without any remaining digits. This leads to common names like flap-footed lizards. Members of the family Cordylidae have only small nubs where their hindlimbs once were.
Legless lizards and snakes share a body plan, but they have plenty of differences. We hope this has taught you a bit about both animals.
Remember that if you want to own a snake or legless lizard, you need to look up the exact species so that you know how to care for them properly. If you have any questions or comments, please leave them below.