The world's smallest snake, averaging just 10cm (4 inches) and as thin as a spaghetti noodle, has been discovered on the Caribbean island of Barbados.
The snake, found beneath a rock in a tiny fragment of threatened forest, is thought to be at the very limit of how small a snake can evolve to be.
Females produce only a single, massive egg - and the young hatch at half of their adult body weight.
This new discovery is described in the journal of Zootaxa.The snake - named Leptotyphlops carlae - is the smallest of the 3,100 known snake species and was uncovered by Dr Blair Hedges, a biologist from Penn State University, US.
"I was thrilled when I turned over that rock and found it," Dr Hedges told BBC News.
"After finding the first one, we turned hundreds of other stones to find another one."
In total, Dr Hedges and his herpetologist wife found only two females.
Defining species
Dr Hedges thinks that the snake eats termites and is endemic to this one Caribbean island. He said that, in fact, three very old specimens of this species were already in collections - one in London's Natural History Museum and two in a museum in Martinique.
However, these specimens had been misidentified.
Dr Hedges explained the difficulty in defining a new species when the organism is so small.
"Differences in small animals are much more subtle and so are frequently over-looked," he said.
Modern genetic fingerprinting is often the only way to tell species apart.
"The great thing is that DNA is as different between two small snakes as it is between two large snakes, allowing us to see the differences that we can't see by eye," explained Dr Hedges.
Researchers believe that the snake - a type of thread snake - is so rare that it has survived un-noticed until now.
But with 95% of the island of Barbados now treeless, and the few fragments of forest seriously threatened, this new species of snake might become extinct only months after it was discovered.
Smallest of the small
In contrast to other species of snake - some of which can lay up to 100 eggs in a single clutch - the world's smallest snake only produces a single egg.
"This is unusual for snakes but seems to be a feature of small animals," Dr Hedges told BBC News.
By having a single egg at a time, the snake's young are one-half the length of the adult. That would be like humans giving birth to a 60-pound (27kg) baby
Dr Hedges added that the snake's size might limit the size of its clutch.
"If a tiny snake were to have more than one offspring, each egg would have to share the same space occupied by the one egg and so the two hatchlings would be half the normal size."
The hatchlings might then be too small to find anything small enough to eat.
This has led the researchers to believe that the Barbadian snake is as small as a snake can evolve to be.
The smallest animals have young that are proportionately enormous relative to the size of the adults producing the offspring. As in the case of Leptotyphlops carlae , the hatchlings of the smallest snakes are one-half the length of an adult. The hatchlings of the biggest snakes on the other hand are only one-tenth the length of the adult producing the offspring. Tiny snakes produce only one massive egg - relative to the size of the mother. This is evolution at work, says Dr Hedges. The pressure of natural selection means the size of hatchlings cannot be smaller than a critical limit if they are to surviveWorld's Smallest Snake Discovered on Barbados
Jeanna Bryner, LiveScience.com Yahoo News 3 Aug 08;
As slim as a spaghetti noodle and able to fit snugly on a U.S. quarter, a new species of snake has been found hiding out in a forest on Barbados. The reptilian runt is now the world's smallest snake.
Blair Hedges, an evolutionary biologist at Penn State, discovered the snake, which just under four inches (10 cm) in length as an adult, in a fragment of forest on the eastern side of Barbados.
Hedges analyzed genetic material from the snake, which along with physical characteristics such as its unique color patterns and scales, provided evidence that the snake was indeed a new species of threadsnake, now dubbed Leptotyphlops carlae.
"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," Hedges said.
The Barbados snake, like its relatives, likely feeds primarily on the larvae of ants and termites.
Like other members of the "small" club, L. carlae only produces one offspring at a time, in this case a single slender egg (some other snakes give birth to live young). In addition, its young are giants relatively speaking. In general, the hatchlings of the smallest snakes are one-half the length of an adult, while the largest snakes have hatchlings that are only one-tenth the length of an adult.
For instance, the hatchling of a king cobra, which can reach a length of 18 feet (5.5 meters), can be as long as about 14 inches (36 cm).
"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," Hedges said. "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."
He added, "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 describes the new species in the Aug. 4 issue of the journal Zootaxa, where he also notes another new snake he discovered on the nearby island of St. Lucia. Also a type of threadsnake, the new species is just about as small as the Barbados one.
The finding doesn't surprise Hedges, who explains how unique organisms tend to be found on islands where species can evolve over time to fill the little nooks and crannies that are available as places to live, or to consume perhaps foodstuffs and other resources, unoccupied by other organisms.
The research was funded by NASA and the National Science Foundation.
World's smallest snake is as thin as spaghetti
Will Dunham, Yahoo News 3 Aug 08;
Scientists have identified the world's smallest snake -- a reptile about 4 inches long and as thin as spaghetti that was found lurking under a rock on the Caribbean island of Barbados.
The new species, named Leptotyphlops carlae, is smaller than any of the other 3,100 previously known snake species, according to Pennsylvania State University biologist Blair Hedges, who also had helped find the world's smallest frog and lizard.
It is one of about 300 different species of threadsnake and is a dark brownish gray with two yellow stripes, Hedges said. It was determined to be a newly identified species due to genetic differences from other snakes and its unique color pattern and scales, he said.
The snake, which is not venomous, eats termites and termite larvae but little is known about its behavior, including whether it is nocturnal, Hedges said. It was found in 2006 in a forest on the eastern side of Barbados.
"It was under a rock. We got two of them," Hedges said in a phone interview. "It's about as wide as a spaghetti noodle."
The snake is about 0.2 inches (5 mm) shorter than another species from the Caribbean island of Martinique.
"When you get down that small, every millimeter counts," said Hedges, whose findings were published in the scientific journal Zootaxa on Sunday.
The biggest and smallest types of animals often are found living on islands where species over time can fill ecological niches in habitats without competition from other creatures not living in the isolated locations.
The world's longest snake is the reticulated python, which grows to 33 feet long and lives in Southeast Asia.
Snakes have lived since the time of the dinosaurs. The oldest known fossil snakes date from around 100 million years ago. The first snakes -- thought to have evolved from lizards -- actually had very small limbs.
Hedges thinks the new one may be at or near the minimum possible size for snakes. It lays a single slender egg that takes up a major part of the mother snake's body, he said.
(Editing by Julie Steenhuysen and Mohammad Zargham)