BLIND SNAKES: Typhlopidae

BLACKISH BLIND SNAKE (Ramphotyphlops nigrescens): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

Most blind snakes are small, with many species reaching less than 12 inches (31 centimeters) in length at full size. Adult flowerpot snakes, for example, reach only 4 to 6.5 inches (10 to 16.5 centimeters) long. A few species, however, can grow to more than 24 inches (61 centimeters). The largest, known as Peter's giant blind snake or the Zambezi blind snake, can top 3 feet (0.9 meters) in length and weigh 1.1 pounds (0.5 kilograms).

The typical blind snake is smooth and shiny with a tube-shaped body. Usually, the head, body, and tail have about the same diameter, although in a few of the larger species, the back half of the animal may grow fat and become quite thick. The scales on their backs are thick and noticeably overlap one another. In some other families of snakes, the scales barely overlap, if they overlap at all. Such an arrangement of overlapping, thick scales gives the blind snakes a strong protective cover.

Blind snakes have short heads, typically with small eyes covered by a see-through scale and a small mouth that opens on the underside of the snake rather than on the front of the head like most other snakes. In some species, the snout is rounded, but in others it may flatten out toward the front, become pointed or hooked, or have some other shape. A few species have little bits of flesh that stick out of the front of the snout and are used by the snake to feel its way along the dark, underground tunnels in which it lives. The tails are usually rather short and often tipped with a single, thorny spine. The spine is especially noticeable in Typhlops depressiceps and Acutotyphlops subocularis. The tail in a snake begins at the vent, a slitlike opening on the snake's underside. They range from tails that make up less than 1/100th of the body length to tails in some species that consist of 1/10th of the overall body.

Many blind snakes have brown, dark gray, or black backs, and a few have bright patterns, such as speckles, blotches, or stripes of white, yellow, orange, or blue. The bellies are often a lighter color than the backs. A few of the blind snakes, including the Xenotyphlops grandidieri, are completely uncolored and look a rather sickly white.

GEOGRAPHIC RANGE

Blind snakes are found in tropical areas nearly around the world, including New Guinea and Australia, Southeast Asia, Africa and Madagascar, the Middle East, southeastern Europe, Mexico, Central America, and northern South America. They are also found on many islands in the Pacific and Indian oceans and in the West Indies. One species, commonly called the flowerpot blind snake or Brahminy blind snake, has traveled throughout the world, including the United States, in plant shipments. Many people mistake this species for an earthworm, but the snake is shiny, has a light-colored underside, and lacks the rings around its body that worms have.

HABITAT

Blind snakes are burrowing species that spend most of their lives either underground or out of sight under logs, tree bark, stones, or in some other hiding place. Some will even slither into ant or termite hills. Rainy weather seems to persuade many blind snakes to leave their underground homes and crawl out onto land. A few species have been found in trees, but they may not actually live there and instead be just visiting to look for a meal. Some blind snakes live in wet rainforests, but other species survive quite well in deserts. Many others live in grasslands, dry forests, farm fields, sandy beaches at the oceanside, or high up mountainsides. Almost half of the species are found only on islands, and about 85 percent of all species of blind snakes live only in the Old World, which includes Asia, Europe, and Africa in the Eastern Hemisphere.

DIET

Blind snakes eat termites, ants, worms, and other small invertebrates (in-VER-teh-brehts). Invertebrates are animals without backbones. Some of the insects attempt to bite or sting in defense, but the thick, overlapping scales on the blind snake protect it from harm. The snakes follow ant trails to their nests by flicking out their tongues, which they use to smell and taste the trail. They are very fast eaters, sometimes gobbling up to 100 insects in just a minute's time. They can eat so rapidly because their upper teeth can be pushed out and then pulled back into the mouth, somewhat like a fast-moving rake. When they find an anthill, for example, they can rake through it and pull in prey very quickly.

BEHAVIOR AND REPRODUCTION

As is true with many other burrowing species that remain out of sight most of the time, scientists know little about their behavior or reproduction. When they are dug out of their burrows, the snakes quickly try to bury themselves again. If they are captured, they will wiggle wildly, ooze a bad-smelling material from the vent area, release their body waste, and/or poke the tail spine into the attacker. Any of these actions can cause the attacker to drop the snake. Occasionally, up to twenty individuals from some species of blind snakes coil up together under a stone. Scientists are unsure why they do it, but they think the snakes are just sharing a good spot.

NOT THE WHOLE SKIN

Snakes do not shed all of their skin. Instead, they shed only the outermost layer, called the stratum corneum (STRAT-um kor-NEE-um). When a snake sheds, or molts, the stratum corneum comes loose, and the snake slips out of it so that it peels off and leaves a complete, inside-out shed that is thin and nearly see-through. In the blind snake of the family Typhlopidae, which has an exceptionally thick stratum corneum, the shed comes off not in an entire piece but in bits and pieces that look like a number of rubbery rings.

Most blind snakes lay eggs, but in a few species, the eggs may hatch inside the mother so that she gives birth to live baby snakes. The flowerpot snake may be parthenogenetic (PAR-thih-no-jeh-NEH-tik), which means that the females do not need males to fertilize their eggs in order to have babies. It is the only parthenogenetic snake, and one of the few parthenogenetic vertebrates in the entire animal kingdom. Vertebrates (VER-teh-brehts) are animals with backbones. Among blind snakes overall, small or especially thin species have fewer eggs — sometimes just one, raisin-sized egg. Larger species may have more than fifty eggs that are the size of large grapes. Eggs probably hatch in one to two months, but some hatch in just a week. Many of the blind snakes mate during only one season a year, usually in late spring, but others appear to mate all year long.

BLIND SNAKES AND PEOPLE

Many African and Asian cultures mention blind snakes in their legends and folklore.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists the Mona Island blind snake as Endangered, which means it faces a very high risk of extinction in the wild. It also lists the Christmas Island blind snake as Vulnerable, which means it faces a high risk of extinction in the wild. Scientists know little about the wild populations of many species, however, so others may be at risk.

BLACKISH BLIND SNAKE (Ramphotyphlops nigrescens): SPECIES ACCOUNT

Physical characteristics: The blackish blind snake, also known as the English blind snake, has a dark back and lighter belly. The back may be black, purple, or pinkish brown, while the underside is pink or off-white. The vent may have a dark blotch on either side. The snout is short and rounded. Size ranges from 3.8 to 22.7 inches (9.7 to 57.6 centimeters) long, and the females are much larger than the males.

Geographic range: Blackish blind snakes live in the eastern half of Australia.

Habitat: People usually see these snakes while turning over rocks or other items in gardens, farm fields, or even in city lots. The snakes also live in similar hiding spots in the woods and along the coastline.

Diet: Blackish blind snakes eat ant larvae (LAR-vee) and pupae (PYU-pee), which are the stages in an ant's life between egg and juvenile. They will also eat worms and other small invertebrates once in a while. A single blackish blind snake can eat 1,500 ants or more at one sitting. The snakes usually only feed in the spring and summer.

Behavior and reproduction: Blackish blind snakes are a burrowing species that spends much of its time underground. Up to thirty members of the species sometimes group together to share a good spot under a stone or in some other hiding spot. After a heavy rain, blackish blind snakes may leave their burrows and slither about on the ground, sometimes even climbing into trees. This species mates in late spring, and the females lay five to twenty grape-sized eggs at a time in the summer.

Blackish blind snakes and people: People and these snakes generally leave one another alone.

Conservation status: The species is not listed as endangered or threatened. ∎

FOR MORE INFORMATION

Books

Burnie, David, and Don Wilson, eds. The Definitive Visual Guide to the World's Wildlife. New York: DK Publishing, 2001.

Cogger, H. G. Reptiles and Amphibians of Australia. Fifth ed. Ithaca, NY: Comstock Publishing Associates/Cornell University Press, 1994.

Ehmann, H., and M. J. Bamford. "Family Typhlopidae." In Fauna of Australia. Vol. 2A, Amphibia & Reptilia, edited by C. J. Glasby, G. J. B. Ross, and P. L. Beesley. Canberra: Australian Government Publishing Service, 1993.

FitzSimons, V. F. M. Snakes of Southern Africa. Cape Town and Johannesburg: Purnell and Sons, 1962.

Grace, Eric, ed. Snakes. San Francisco: Sierra Club Books for Children, 1994.

Greer, A. E. The Biology and Evolution of Australian Snakes. Chipping Norton, New South Wales, Australia: Surrey Beatty & Sons, 1997.

Lee, Alfonso Silva. Coquí y sus amigos / Coquí and His Friends. Pangaea, Bilingual edition, 2000.

McDiarmid, R. W., J. A. Campbell, and T. A. Touré. Snake Species of the World: A Taxonomic and Geographic Reference. Vol. 1. Washington, DC: Herpetologists' League, 1999.

Mehrtens, John M. Living Snakes of the World in Color. New York: Sterling Publishing, 1987.

Schwartz, A., and R. W. Henderson. Amphibians and Reptiles of the West Indies: Descriptions, Distributions, and Natural History. Gainesville: University of Florida Press, 1991.

Taylor, Barbara. Snakes. New York: Lorenz, 1998.

Web sites

"Blindsnake." Wild Kids. http://www.amonline.net.au/wild_kids/reptiles/blind_snake.htm (accessed on September 22, 2004).

"Blind Snakes, Family Typhlopidae." Australian Museum. http://www.livingharbour.net/reptiles/snakes_blind.htm (accessed on September 22, 2004).

"Blind Snakes (Family Typhlopidae: South-east Queensland." Queensland Museum Explorer. http://www.qmuseum.qld.gov.au/features/snakes/seq/typhlopidae.asp (accessed on September 23, 2004).

"Brahminy Blind Snake." Ohio Public Library Information Network. http://www.oplin.org/snake/fact%20pages/brahminy_blind/brahminy.html (accessed on September 22, 2004).