Woodsnakes and Spinejaw Snakes: Tropidophiidae

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The woodsnakes and spinejaw snakes are small-to-medium-sized snakes that resemble boas. Colors range from gray to brown, and most have faint blotches or stripes. Some have smooth scales, and others have scales with ridges, or keels. Among those with smooth scales, the Oaxacan dwarf boa has scales that shine different colors depending on how the light hits them. Scales that do this are known as iridescent (IH-rih-DEH-sent). On the other hand, some members of this family have dull-looking scales with noticeable keels. The Cuban black and white dwarf boa even has scales that change color from darker during the daytime to lighter at night.

The smallest member of this family is the Cuban dusky trope, which reaches at most 12 inches (30 centimeters) long. The largest is the dusky dwarf boa, which can grow to 41 inches (104 centimeters) in length.

Some people believe that this family should be split in two with one keeping the name Tropidophiidae and the other falling under a new family called Ungaliophiidae. Occasionally, some books will place these snakes under the family Boidae, but although some have the common name of dwarf boas, they are not actually boas.


They are found from Brazil to Mexico and in the West Indies. Some species are found in both Malaysia and Borneo.


Different members of this family may prefer dry and open, shrubby forests; rainforests; the rocky sides of hills, as well as cliffs; farm fields; and even caves. Usually, they try to find a spot within the habitat that has conditions falling about halfway between wet and dry. Only two species make their homes high in mountains. Several species within this family are so rarely seen that they are only known by their scientific names.


Much of the information about the diet of these snakes comes from captive snakes rather than those in the wild. The West Indian species of the genus Tropidophis eat anoles, which are small, long-tailed lizards. Species in the genus Exiliboa feed on small salamanders and on frog eggs, while those in the genus Trachyboa make both fishes and amphibians part of their diet. Amphibians include such animals as salamanders and frogs. The dusky dwarf boa, which is the largest member of the family, will eat small mammals and birds. In captivity, many larger snakes in this group will eat baby mice.


The snakes spend a good deal of time actively, but slowly, slithering through their habitat, apparently on the hunt for food. Scientists suspect that they also find hiding places, where they remain still and wait for the meal to come to them. This tactic, called ambush, is very effective for snakes like these that blend into the background very well. Most of the woodsnakes and spinejaw snakes live on the ground, but a few will also climb a few feet into trees or shrubs. The bromeliad woodsnakes are the best climbers in the family and will slink into plants, known as bromeliads (broh-MEE-lee-ads), that grow on the trunks and branches of tall trees.


Humans have helped many species move from one place to another. Sometimes, people purposely introduce a new species. For example, people who move to a new country frequently bring along a favorite plant to put it in the garden and remind them of the homeland. Often, however, animals hitchhike with people when they travel. The woodsnakes and spinejaw snakes are no exception. The Panamanian dwarf boa has made its way from its home in Central America to both Europe and the United States by stowing away in bunches of bananas.

Most of the woodsnakes and spinejaw snakes are active mainly at night, but they also come out during the day to sunbathe, or bask. When they feel threatened, the majority of the species will roll their bodies into a ball, rather than strike and bite as many other snakes do. Members of the genus Trachyboa coil into a flat disk instead of a ball, burying the head in the center of the disk. If an attacking animal, or predator (PREH-duh-ter), bites at a woodsnake, a bad-smelling material may ooze out of the snake's vent, a slitlike opening on the belly side of the animal. The odor is sometimes enough to cause the predator to leave. Only rarely will the snake bite back at an attacking animal. Some species in the genus Tropidophis have a rather unusual way of protecting themselves from predators. If a predator bothers them enough, they will begin to bleed from the mouth, nostrils, and eyes. Because the bleeding, or hemorrhaging (HEHM-rihj-ing), can start automatically—even though the snake has no injury—it is called autohemorrhaging (aw-toe-HEHM-rihj-ing).

Female woodsnakes and spinejaw snakes give birth to baby snakes, instead of eggs. Few people have studied this snake, so little additional information is available about their reproduction or behavior.


Some are occasionally captured for the pet trade, but for the most part, people have little if any contact with these snakes.


This species is not listed as endangered or threatened. One species, the Navassa woodsnake, was noted as extinct in the 1990s, likely due to changes in its habitat and deaths from mongoose attacks. A mongoose is a ferretlike, meat-eating animal that is an excellent hunter.


Physical characteristics: Also known as the bromeliad boa, bromeliad dwarf boa, and banana boa, the southern bromeliad woodsnake is a thin, light gray or tan snake with black triangular marks on its back. It has smooth scales along its body with one large scale on top of its snout. Adults reach about 30 inches (76 centimeters) in length.

Geographic range: They live in Costa Rica, Nicaragua, and Panama in Central America and also in Colombia in northern South America.

Habitat: It lives in a variety of forests, except those of the mountains, often crawling among the plants that grow on the upper branches and high up in the trunks of trees. It also spends considerable time on the ground.

Diet: In captivity, southern bromeliad woodsnakes will eat lizards or rodents, although young snakes typically will only eat lizards. Scientists know little about their diet in the wild, but it probably includes lizards and frogs.

Behavior and reproduction: A mild-mannered snake, this species does not bite human handlers. Even when threatened, it will not bite and instead simply coils into a ball to wait for the danger to pass. It has another defense, however, which it will use if it feels particularly frightened. That defense is an ooze that seeps from its vent and has a strong enough smell to scare off most attackers. Females do not lay eggs and instead have baby snakes. The young are about 6 inches (15 centimeters) long at birth. Scientists know little else about this snake's behavior or reproduction.

Southern bromeliad woodsnakes and people: People rarely see this snake in the wild or in pet stores.

Conservation status: Scientists know so little about this snake, including how many of them live in the wild, that they cannot make any statements about its conservation status. ∎



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Web sites

"Talking Taino: Lizards and Snakes." Times of the Islands. Summer 2004. http://www.timespub.tc/Natural%20History/Archive/Summer2003/ttsnake.htm (accessed on September 15, 2004).

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Woodsnakes and Spinejaw Snakes: Tropidophiidae

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