Legless lizards are distinct reptiles often mistaken for snakes. This article clarifies what legless lizards are and highlights the key characteristics that differentiate them from snakes.
Understanding Legless Lizards
Legless lizards belong to the order Squamata, like snakes and other lizards. Their lack of limbs results from convergent evolution, where limb reduction or loss occurred independently in many lizard lineages over millions of years. This adaptation is often associated with a burrowing lifestyle, where limbs could hinder movement. Despite their modified body plan, these animals retain anatomical features that classify them as lizards, such as the presence of a pelvic girdle or at least a retained ilium. Some species even possess tiny, non-functional remnants of hind limbs.
Distinguishing Them From Snakes
Differentiating legless lizards from snakes involves observing several physical characteristics. Legless lizards have movable eyelids, allowing them to blink, unlike snakes, which have fused, transparent scales covering their eyes. Most legless lizards also have visible external ear openings, a feature absent in snakes, which detect vibrations through their jawbones.
Their undersides also differ. Legless lizards generally have multiple rows of small, uniform scales on their belly, while snakes typically have a single row of broad, rectangular scales specialized for locomotion. Lizards shed their skin in pieces, while snakes shed theirs in one continuous piece.
Jaw structure and tail length also provide clues. Legless lizards have a more rigid jaw structure, limiting their ability to consume prey larger than their head. Snakes, conversely, have highly flexible jaws that can unhinge, allowing them to swallow much larger prey. Legless lizards often have a very long tail, up to two-thirds of their body length, and many species can detach it as a defense mechanism. Snakes typically have a body that is mostly trunk with a shorter tail, which they cannot detach.
Examples Across the Globe
Legless lizards are found worldwide, showcasing this evolutionary adaptation. Glass Lizards (Ophisaurus genus), found in North America, Europe, and Asia, are a well-known group. They inhabit diverse environments like grasslands, woodlands, and sandy areas, often burrowing. Their common name comes from their ability to shed their long, fragile tails when threatened, which tend to break into pieces.
The Slow Worm (Anguis fragilis), common across Europe and parts of Asia, is another example. Despite its name, it is neither a worm nor a snake. Slow Worms prefer habitats like heathlands, grasslands, and gardens, found in compost heaps and under logs. Like Glass Lizards, they can shed their tails to escape predators.