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The snake named Leptotyphlops carlae, as thin as a spaghetti noodle, is resting on a U. S. quarter. Blair Hedges, professor of biology at Penn State University, described the species and determined that it is the smallest identified snake species. Photo Courtesy Blair Hedges, Penn State.
The world's smallest species of snake, with adults averaging just less than four 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 described by Blair Hedges, an evolutionary biologist at Penn State.
Hedges described the new snake -- a type of threadsnake -- which lives in a tiny forest fragment on the eastern side of Barbados. 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 seek to measure both adult males and adult females of a species to determine its average size. Using these methods, Hedges determined that this species, which he named Leptotyphlops carlae, is the smallest known snake species.
Hedges said the Barbados snake may be near the minimum possible size for snakes, though he cannot say for sure that no smaller species exists -- several other snake species are nearly as small.
"Snakes may be prevented by natural selection from becoming too small because, below a certain size, there may be nothing for their young to eat," said Hedges, adding that the Barbados snake, like others to which it is related, likely feeds primarily on the larvae of ants and termites.
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.
"If a tiny snake were to have two offspring, each egg could occupy only half the space that is devoted to reproduction within its body. But then each of the two hatchlings would be half the normal size, perhaps too small to function as a snake or in the environment," said Hedges. "The fact that tiny snakes produce only one massive egg -- relative to the size of the mother -- suggests that natural selection is trying to keep the size of hatchlings above a critical limit in order to survive."
Hedges has described more than 65 new species of amphibians and reptiles throughout the Caribbean in the course of his genetic and evolutionary studies. In the paper in which he describes the Leptotyphlops carlae snake, he also describes another snake that lives on the nearby island of St. Lucia, a threadsnake that is nearly as small as the Barbados snake.
The most recent description was published on August 4, 2008 in the journal Zootaxa. Funding for the research was provided by the National Science Foundation and the National Aeronautics and Space Administration.