GECKOS AND PYGOPODS: Gekkonidae

PHYSICAL CHARACTERISTICS

Geckos range in size from 0.67 inch (17 millimeters) to 14 inches (35.6 centimeters) in length. The smallest gecko weighs about 0.07 ounce (1.98 grams). The largest gecko, which lives in rainforests, can weigh up to 1.5 pounds (680 grams). While most geckos are brown, gray, or black, a few are yellow, red, blue, orange, or green. They may be plain, or they may have stripes or spots. Colors on the head and neck may be different from the colors on the back. The nocturnal geckos, or those that are active at night, are plainer than the diurnal (die-UR-nuhl) geckos, or those active in the daytime, which tend to have brighter colors.

Geckos usually have flattened bodies and four short limbs, or legs. Each limb has five toes. Some species have claws on each foot. Other types of geckoes have widened toe pads. These toe pads are made to allow the gecko to stick to smooth surfaces. Geckos have large eyes that are open all the time. Except for a few species, the eyes do not have movable eyelids. Instead, the eyes are protected by clear, see-through scales, or thin coatings. Geckos clean these scales regularly with their long tongues. Most geckos are nocturnal. These geckos have vertical pupils (PYU-puhls), meaning that they are positioned straight up and down, in the center of their eyes. Diurnal geckos have round pupils in the center of their eyes. Pupils are parts of the eye that allow light to enter.

Gecko skin is soft and loose and typically covered with granular, or grainy, scales that do not overlap. A few species have smooth skin. Gecko tails come in varied shapes. Many geckos have tails shaped like carrots or turnips. Some have rounder tails that are used to store food.

Pygopods (PIE-go-pods) are also called "snake lizards," limbless lizards," and "flap-footed lizards." They range in length from less than 8 inches (20.3 centimeters) to 2 feet (61 centimeters). Their colors range from pale yellow to dark brown, with or without a pattern of spots or stripes.

Pygopods have a narrow face and an almost snakelike appearance. The snout, or nose area, is pointed. The eyes are always open, protected by transparent, or clear, scales. Most pygopods do not have an outside ear opening. They have no front limbs and only flaplike hind limbs. Their long tails break off easily.

GEOGRAPHIC RANGE

Pygopods are found in Australia and New Guinea. Geckos are found in the tropics and subtropics, the warmer areas of the world. These areas include India, Nepal, Burma, the Malaysian peninsula, China, the Philippines, Indonesia, New Zealand, Saudi Arabia, Central America, and South America. Geckos and skinks are often the only land reptiles on remote islands in the ocean. A few gecko species have been found in southern Europe, southern Siberia, and the southwestern United States.

HABITAT

Geckos live in a variety of habitats. Their preferred living areas include coniferous forests, with pine and other evergreen trees, and deciduous forests, where trees, such as maples, lose their leaves each year. They also live in rainforests, tropical forests that get at least 100 inches of rain per year; this type of forest has many very tall evergreen trees that form a thick umbrella of leaves and branches overhead. Geckos also live in deserts and in grassland, or meadows. Pygopods live in desert and in grassland.

DIET

Nearly all geckos eat insects and spiders. A few larger species eat small snakes, small lizards, and baby birds. In some habitats, geckos also eat plant pollen and ripe fruit. Smaller pygopods are insect eaters, and larger ones eat snakes and lizards.

BEHAVIOR AND REPRODUCTION

Most geckos are nocturnal. During the day they typically hide under tree bark or in tree hollows. In the early evening they come out to feed and to look for mates. The diurnal species are most active in the late morning and middle of the afternoon. In tropical areas, which are warm throughout the year, geckos stay active all the time. In other areas, geckos enter burrows or rock cracks and remain there most of the time during the cool season.

Geckos typically live by themselves; only a few types live in groups. Some species are seen around peoples' homes. Males defend their feeding and resting places by using warning sounds, usually many clicks and chirps. Defense methods include running away; squirting a sticky fluid at predators, or animals that hunt them to eat them; biting; and shedding their tails. A gecko's tail will continue to wriggle after it is shed, fooling the predator and allowing the gecko to escape. Some gecko species also can shed body skin if they are grabbed by other animals. This skin regrows, as do the tails.

Geckos are the most vocal lizards, meaning that they make the most sounds. Most geckos make several different sounds, including barking, croaking, squeaking, and chirping. The giant Asian Tokay gecko makes a loud noise that sounds to some people like "geh-oh." It is possibly from this sound that the gecko gets its name.

During mating season, the males of some species have violent fights over females.

After mating, most gecko females lay a nest of two hard-shelled or leathery eggs. Some tropical species lay eggs throughout the year, and others have just one clutch, or nest of eggs. Some lay several egg groups within a mating season. Eggs are placed under loose bark or under a rock, where it is slightly damper than it is in the open air. Hatching occurs in six to ten weeks. A few species give birth to living young instead of laying eggs.

WALKING UP WALLS

Scientists have investigated how geckos can walk up shiny walls and across ceilings. They found that geckos have millions of tiny foot hairs, called "setae" (SEE-tee), on each toe pad. The tips of these setae are very sticky. Geckos can hang from a wet or dry ceiling attached by just one toe. How do they get their feet off the ceiling and move? Scientists think that they peel foot hairs off like tape.

Because pygopods are secretive, not much is known about them. They hide in rocky areas, in tall grass, and in burrows. Some are active during the day. The desert species move about at night. After mating, females lay two eggs per clutch.

GECKOS, PYGOPODS, AND PEOPLE

Pygopods seldom have anything to do with people. Some gecko species live near human homes. They are valuable in insect control, eating mosquitoes, flies, and cockroaches. In some areas of the world, deforestation, or the cutting down of trees, destroys their habitat. The killing of geckos by rats, cats, and other predators has led to declines in the numbers of geckos in some areas. In parts of Asia, geckos are used in medicines. Geckos, especially the brightly colored ones, are collected for the legal and illegal pet trade. A few species breed, or multiply, readily in captivity and do well.

CONSERVATION STATUS

The conservation status of most species is unknown. Because of illegal pet trade collection, the World Conservation Union (IUCN) lists one brightly colored group of geckos as Endangered and internationally protected.

WESTERN BANDED GECKO (Coleonyx variegatus): SPECIES ACCOUNTS

Physical characteristics: The western banded gecko, also known as the banded gecko, is 4.5–6 inches long (11–15 centimeters) from its head to the end of its tail. The skin on its back is made up of small, grainy scales. The skin is delicate, soft, and loose. The gecko's back and tail are cream colored, with wide black or brown stripes that run from side to side. The tail is long, and the head is somewhat large. The eyes have eyelids that move, with pupils that are vertical.

Geographic range: Western banded geckos are found in the southwestern United States and northern Mexico.

Habitat: Western banded geckos are found in dry desert dune, or hill, areas; dry juniper-oak woodlands; desert areas with small shrubs; and rocky desert sites.

Diet: Western banded geckos eat insects and spiders. Surplus, or extra, food may be stored as fat in the tail.

Behavior and reproduction: Western banded geckos move about only at night. They rest during the day under rocks or within the burrows, or underground homes, of small animals. During the day these areas are damper than areas above ground. Several of these geckos may rest together in the burrows. If the burrow is disturbed, the western banded gecko may twitch its tail like a cat. If it is attacked, it runs away quickly. It may leave its tail behind to distract the attacker.

During the mating season, western banded gecko males face each other and make threatening movements. After mating, females lay two or more egg groups, with two eggs in each group. Hatching takes place in thirty to forty-five days.

Western banded geckos and people: Western banded geckos are kept as pets, and they have been successfully bred in captivity. They have no other human interaction.

Conservation status: The western banded gecko is not threatened. ∎

HOUSE GECKO (Hemidactylus frenatus): SPECIES ACCOUNTS

Physical characteristics: The house gecko is grayish, pinkish, or pale brown with darker flecks. The color may vary, depending on the surrounding temperature. It also may vary depending on the surface on which the gecko is resting; this gecko can blend with its background, such as a tree branch or a leafy area. The body is flattened. This gecko grows to 2.6 inches (66 millimeters) in length, from the head to the base of the tail. It has toe pads on each of its toes, and the first toe is smaller than the rest.

Geographic range: House geckos exist in Southeast Asia, the Philippines, Taiwan, and much of Micronesia, Melanesia, and Polynesia. It was introduced, or brought by people, into tropical Australia, eastern Africa, Mexico, and the United States.

Habitat: These geckos live among many types of vegetation, or greenery, including tropical rainforest and dry scrubland, or land covered with low trees and bushes. They are often found around human homes and rubbish dumps.

Diet: House geckos eat insects.

Behavior and reproduction: This gecko is active at night, although it may be seen outside on cloudy days. Male house geckos can be unfriendly and mean. This is especially true when there are many of them in one area and plenty of food. They can produce several types of clicking sounds, including "chi-chak."

After mating, females can store sperm (SPUHRM), the male reproductive cells that fertilize the female's eggs. The females lay groups of hard-shelled eggs throughout the year, and the eggs hatch in forty-five to seventy days.

House geckos and people: This species is often found in and around people's homes.

Conservation status: The species itself is not threatened, but it may cause a decrease in native geckos in the areas where it is introduced. House geckos are unfriendly and compete for the food supply of other gecko species. ∎

FOR MORE INFORMATION

Books:

Bartlett, Richard D. Geckos: In Search of Reptiles and Amphibians. New York: E. J. Brill, 1988.

Bartlett, R. D., and Patricia P. Bartlett. Geckos: Everything about Selection, Care, Nutrition, Diseases, Breeding, and Behavior. Hauppauge, NY: Barron's Educational Series, 1995.

Behler, John L. The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Knopf, 1979.

Capula, Massimo. Guide to Reptiles and Amphibians of the World. New York: Simon & Schuster, 1989.

Hernandez-Divers, Sonia. Geckos (Keeping Unusual Pets). Portsmouth, NH: Heinemann Library, 2002.

Mattison, Chris. The Care of Reptiles and Amphibians in Captivity. London: Blandford Press, 1987.

Miller, Jake. The Leopard Gecko. New York, NY: PowerKids Press, 2003.

Sprackland, Robert G., Jr. All about Lizards. Neptune City, NJ: T. F. H. Publications, 1977.

Uchiyama, Ryu. Reptiles and Amphibians. San Francisco: Chronicle Books, 1999.

Periodicals

"At Home in the Rocks, a New Gecko Emerges." National Geographic (June 1997): Geographica.

"Barking Gecko." National Geographic (October 1989): 26–29.

"Fat-Tailed Gecko." Ranger Rick (May 1994): 14–15.

"Leopard Gecko." Ranger Rick (November 1994): 4–7.

"Where'd the Gecko Go?" National Geographic World (July 1985): 38.

Web sites

Autumn, Kellar. "Gecko Story." http://www.lclark.edu/autumn/dept/geckostory.html (accessed on August 8, 2004).

Muir, Hazel. "Minute Gecko Matches Smallest Living Reptile Record." NewScientist.com. December 3, 2001. http://www.newscientist.com/news/news.jsp?id=ns99991635&lpos;=related_article2 (accessed on August 9, 2004).

Schweitzer, Sophia. "Guardian Geckos." Coffee Times.http://www.coffeetimes.com/geckos.htm (accessed on August 9, 2004).