Posted on August 4, 2008  Comments (3)

The world’s smallest species of snake, Leptotyphlops carlae, with adults averaging just under 4 inches in length, has been identified on the Caribbean island of Barbados. The species — which is as thin as a spaghetti noodle and small enough to rest comfortably on a U.S. quarter — was discovered by Blair Hedges, an evolutionary biologist at Penn State.

Hedges determined that the Barbados species is new to science on the basis of its genetic differences from other snake species and its unique color pattern and scales. He also determined that some old museum specimens that had been misidentified by other scientists actually belong to this new species.

Scientists use adults to compare sizes among animals because the sizes of adults do not vary as much as the sizes of juveniles and because juveniles can be harder to find. In addition, scientists seek to measure both males and females of a species to determine its average size. Using these methods, Hedges determined that this species, is the smallest of the more than 3,100 known snake species.

According to Hedges, the smallest and largest species of animals tend to be found on islands, where species can evolve over time to fill ecological niches in habitats that are unoccupied by other organisms. Those vacant niches exist because some types of organisms, by chance, never make it to the islands. For example, if a species of centipede is missing from an island, a snake might evolve into a very small species to “fill” the missing centipede’s ecological niche.

In contrast to larger species — some of which can lay up to 100 eggs in a single clutch — the smallest snakes, and the smallest of other types of animals, usually lay only one egg or give birth to one offspring. Furthermore, the smallest animals have young that are proportionately enormous relative to the adults. For example, the hatchlings of the smallest snakes are one-half the length of an adult, whereas the hatchlings of the largest snakes are only one-tenth the length of an adult. The Barbados snake is no exception to this pattern. It produces a single slender egg that occupies a significant portion of the mother’s body.

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Hedges found the new snake, a type of threadsnake, in a tiny forest fragment on the eastern side of Barbados. He believes the species is rare because most of its potential habitat has been replaced by buildings and farms. “Habitat destruction is a major threat to biodiversity throughout the world,” he said. “The Caribbean is particularly vulnerable because it contains an unusually high percentage of endangered species and, because these animals live on islands, they have nowhere to go when they lose their habitat.”

Hedges has discovered and described more than 65 new species of amphibians and reptiles throughout the Caribbean in the course of his genetic and evolutionary studies.

Funding for the research to be published in Zootaxa was provided by the National Science Foundation and the National Aeronautics and Space Administration. Photo by Blair Hedges.