Alligator Lizards, Galliwasps, and Relatives: Anguidae
ALLIGATOR LIZARDS, GALLIWASPS, AND RELATIVES: AnguidaeTEXAS ALLIGATOR LIZARD (Gerrhonotus liocephalus): SPECIES ACCOUNT
This family contains four groups of lizards: the glass lizards and slowworms, the legless lizards, the galliwasps, and the alligator lizards. Many of these species in the Anguidae family have bodies that are nearly all brown, but some are green, and others have stripes or bands. The glass lizards have especially shiny scales. In a few species, the males are more brightly colored than the females. Among alligator lizards that live in mountainous areas, for example, the females and the juveniles are a drab brown, and the males are bright green or yellowish green. Some, such as the La Selle galliwasp, are small and reach only about 2.8 inches (7 centimeters) in length from head to tail tip. The slowworm, on the other hand, can grow to nearly 20 times that size at 55.1 inches (140 centimeters) long.
In general, the scales of these species are thick and strong, giving them an armor-like covering. Many of the legless lizards and galliwasps have a fold on each side of the body, which allows their bodies to stretch out when they eat a particularly big meal or when a female is pregnant. Some of the species, including the legless lizards, have no limbs and therefore slither about with a twisting motion. A few, such as the Moroccan glass lizard, have no front legs but do have tiny hind legs that look like small flaps located near the vent, which is a slitlike opening on the underside of the animal. The tail in galliwasps, legless lizards, and alligator lizards is usually shorter than the rest of the body, but the tail is far longer than the body in glass lizards. In all lizards, including those without legs, the tail begins at the vent. A few species, such as the Cuban alligator lizard, live in trees and have tails that can wrap around and cling to branches and twigs. In addition, many members of this family have eyelids that they noticeably blink open and shut.
These lizards live in North, Central, and South America, Europe, and Asia. They also make their homes on many islands of the West Indies. One species, the Moroccan glass lizard, lives in northern Africa.
Most of these lizards live on land and on the ground's surface, but they often remain in leaf piles, under stones, or in some other hiding spot. A few make their homes underground, and some spend much of their time in trees. While many species live in moist, low-lying areas, some live high in mountain forests or in dry and shrubby deserts.
These lizards will eat a number of different animals. They typically move very slowly, so their diet includes other slow-traveling things, such as snails, slugs, spiders, some insects, and other invertebrates (in-VER-teh-brehts), which are animals without backbones. When they eat vertebrates (VER-teh-brehts), which are animals with backbones, they tend to dine on bird eggs, baby rodents that are still in the nest, or other small animals, such as salamanders, that are not fast enough to get away.
BEHAVIOR AND REPRODUCTION
Depending on the species, they may be active during the day or at night. They usually stay out of sight, but many species will come out into the open on a sunny day to soak up the warmth. Such sunbathing is called basking. Often, these shy lizards will only expose one part of their bodies at a time while basking, keeping the rest hidden away. Those species that live in colder areas may spend the winter in a deep sleep, known as hibernation (high-bur-NAY-shun).
These lizards are especially known for their behavior when they feel threatened: Most members of this family quickly drop the tail, which may break into several wriggling pieces. While the attacker is looking at or eating the tail, the lizard makes its escape. The lizard grows back the tail, but it is often much shorter than the original one. The glass lizard's regrown tail, for example, is a pointed stump. Some lizards in this family will also defend themselves by wiggling frantically, by smearing a bad-smelling ooze and/or feces on the attacker, or by puffing up the body with air, which may make the lizard appear large enough to scare off an attacker.
Within this family, some species lay eggs and others give birth to baby lizards. Female legless lizards all have one or two live babies in each litter. Depending on the species, female glass lizards and slowworms, galliwasps, and alligator lizards may lay eggs or give birth to baby lizards, with brood sizes from less than five to two dozen or more. In some egg-laying species, the female stays with the eggs, often wrapping her body around them, until they hatch. Most species have young every year, but some, such as the montane alligator lizard, probably only give birth once every two years. During breeding season, males of some species, including the slowworm, will fight by grasping at one another with their jaws. For most species, however, scientists know little about their courtship behaviors.
ALLIGATOR LIZARDS, GALLIWASPS, THEIR RELATIVES, AND PEOPLE
Because many species like to hide, people rarely see them in the wild unless a person is plowing a field or raking leaves in their habitat. Some people mistake the glass lizard's stubby and pointed regrown tail for a stinger, but all lizards in this family are harmless. Several species are fairly common in the pet trade.
LIZARD OR SNAKE?
Several species of lizards, including the glass lizards of the family Anguidae, have no legs. Many people confuse these lizards with snakes. In fact, another common name for the eastern glass lizard is actually glass snake. At least two features, however, can give away this lizard's true identity. Unlike snakes, the eastern glass lizard has eyelids that it can blink shut and has ear openings that look like a hole on each side of the head. Snakes cannot blink shut their eyes and have no visible ear openings. The glass lizards get their name from their tails, which easily break off as if they were made of glass.
According to the World Conservation Union (IUCN), one species is Extinct, which means that it is no longer in existence. This species, the Jamaica giant galliwasp, was last seen in 1840. It probably disappeared because people brought new species, including the mongoose, to Jamaica to kill rats. The mongoose, however, also eats galliwasps and probably played a role in their extinction. In addition, the IUCN names three species as Critically Endangered, which means they face an extremely high risk of extinction in the wild; one species as Endangered, which means it faces a very high risk of extinction in the wild, and one species as Vulnerable, which means it faces a high risk of extinction in the wild. These and other unlisted species are threatened by habitat destruction, particularly in such small places as the islands of the West Indies. The IUCN also lists three species as Data Deficient, which means that scientists have too little information to make a judgment about the threat of extinction.
Physical characteristics: The Texas alligator lizard has a long tail and, unlike some other members of this family, four working legs. Its squarish scales somewhat resemble those of an alligator. Its back is reddish brown, sometimes yellowish, with crooked crossbands of white and black scales. Adults usually range from 9.8 to 15.7 inches (25 to 40 centimeters) in length, but some can be as long as 19.7 inches (50 centimeters).
Geographic range: They live from Texas in the United States to San Luis Potosí in central Mexico.
Habitat: The Texas alligator lizard often lives on rocky hillsides, preferring areas without many plants, although it does sometimes live in dry woods and shrubby areas.
Diet: This slow-moving species spends much of the day searching for various invertebrates, as well as small rodents or other vertebrates, it can capture and eat.
Behavior and reproduction: This species is active during the day. When it feels threatened, it can blow itself up with air, which may make it appear large enough that a predator will leave it alone. Females lay five to thirty-one eggs at least once a year, and they often remain with the eggs until they hatch.
Texas alligator lizards and people: People sometimes collect these lizards for pets.
Conservation status: The Texas alligator lizard is not listed as endangered or threatened. ∎
FOR MORE INFORMATION
Badger, D. Lizards: A Natural History of Some Uncommon Creatures— Extraordinary Chameleons, Iguanas, Geckos, and More. Stillwater, MN: Voyageur Press, 2002.
Capula, Massimo. Simon and Schuster's Guide to Reptiles and Amphibians of the World. New York: Simon and Schuster, 1989.
Mattison, Chris. Lizards of the World. New York, NY: Facts on File, 1989.
"Alligator Lizard." Melissa Kaplan's Herp Care Collection. http://www.anapsid.org/gerrhont.html (accessed on October 20, 2004).
"Eastern Glass Lizard." Yahooligans! Animals. http://yahooligans.yahoo.com/content/animals/species/4313.html (accessed on October 20, 2004).
"Glass Lizard -Glass Snake -Legless Lizard." Melissa Kaplan's Herp Care Collection. http://www.anapsid.org/legless.html (accessed on October 20, 2004).
"Northern Alligator Lizard." Yahooligans! Animals. http://yahooligans.yahoo.com/content/animals/species/4322.html (accessed on October 20, 2004).
"Slender Glass Lizard." Iowa Herpetology. http://www.herpnet.net/Iowa-Herpetology/reptiles/lizards/glass_lizard.html (accessed on October 20, 2004).