Snakes and Lizards: Squamata

The 7,200 species of snakes, lizards, and wormlizards all fall under the order Squamata and are therefore known as squamates (SKWAH-mates). Perhaps the most noticeable difference between the snakes and the lizards are the legs, or the lack of them. Most lizards, except for a few species, have working legs. Snakes are legless. The most noticeable feature of the worm lizards is their earthworm-like body. While they have scales and earthworms do not, worm lizards' scales are arranged in rings and separated with grooves to give them the appearance of an earthworm's ringed body. Most of the worm lizards are legless, although a few have two front legs just behind the head.

Besides smelling with their noses and tasting with their tongues, most squamates also smell with a special organ on the roof of their mouths. They use it by first flicking or otherwise picking up chemicals on the tongue. They then place the tongue on the roof of the mouth at what is called the Jacobson's organ, which smells the chemicals. For hearing, many lizards have ears that are visible as a hole on either side of the head. Neither the snakes nor the wormlizards have the openings for their ears. Scientists believe that snakes can probably only hear very low-pitched sounds, including ground vibrations that they sense in the jaw and send to the ear.

In addition to the presence or absence of ear holes, known as external ears, snakes and lizards have another obvious difference. The majority of lizards have eyelids that close and open. Snakes, on the other hand, have a spectacle over their eyes. A spectacle is a clear scale, which looks much like a contact lens. In other words, a lizard noticeably blinks, but a snake always appears to have its eyes open. Although most squamates have obvious eyes, those species that spend most of their lives underground often have very small eyes, which are sometimes invisible under their scales.

The size of the squamate depends on the species. Among the lizards, the heaviest is the Indonesian Komodo dragon, which can grow to be at least 9.9 feet (3 meters) long and 330 pounds (150 kilograms). Many people consider the crocodile monitor to be the world's longest lizard. It can reach 12 feet (nearly 3.7 meters) long, although some reports claim that the lizards can reach 15 to 19 feet (4.6 to 5.8 meters) long. The smallest lizard, on the other hand, is the jaragua lizard, also known as the dwarf gecko. From one end to the other, adults of this recently discovered species only reach about 1.2 inches (3.2 centimeters) long. Snakes also come in different sizes. Some of the smallest are in the blind snake and slender blind snake families, which include species that only grow to 4 inches (10 centimeters) long and weigh just 0.05 ounces (1.4 grams). This compares to the reticulated python, which often reaches 20 feet (6.1 meters) or more. The largest reticulated python ever discovered was killed in 1912 in Indonesia. This beast measured 33 feet (10.1 meters) in length. The South American green anaconda is another enormous species, often reaching 25 feet (7.7 meters) long and 300 pounds (136 kilograms). Wormlizard adults range from 3.1 inches (8 centimeters) to more than 32 inches (81 centimeters) long.