Snakes hold thread of evolution evidence
The threadsnake is small enough to coil itself on a dime.
January 3, 2000
Web posted at: 2:39 p.m. EST (1939 GMT)
By Environmental News Network staff
Only six to eight inches long, the diminutive threadsnake boasts a unique feeding system that may have great evolutionary and ecological importance, according to a recent study.
"Typically when we think of snakes feeding, we think of pythons and boas eating large animals," said Nate Kley, an evolutionary biologist and herpetologist at the University of Massachusetts at Amherst. "The snakes are able to do this because they have very flexible hinged jaws. Most snakes savor their infrequent feasts, taking anywhere from several minutes to several hours to consume a meal."
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Unlike most of their cousins, threadsnakes survive on a daintier diet that consists principally of the pupae and larvae of ants. Instead of consuming their meals in one big gulp, threadsnakes eat at a rate of three or four bites each second. They are the only known vertebrates to use only their lower jaw to devour prey.
Dinner for this threadsnake is an ant pupa often found under rocks or inside rotting logs.
The front parts of the threadsnake's triple-jointed lower jaw swing in and out of the mouth "like a pair of saloon doors," dragging prey quickly into the esophagus, Kley explains.
Scientists generally agree that lizards are the evolutionary forefathers of snakes.
Kley views the foraging strategy of threadsnakes as a link between snakes and lizards. Like lizards, threadsnakes eat small prey; like other snakes, they gorge themselves on huge meals, eating thousands of ants or termites at a time. These patterns lead Kley to believe that threadsnakes may be among the most primitive groups of snakes.
The rapid-fire eating habit of the threadsnake may be the result of its hazardous foraging strategy, Kley said. When threadsnakes invade ants' nests to find sufficient food, they have to eat very quickly to avoid being attacked or even killed by large and powerful worker ants guarding the nests.
"The evolutionary origin of snakes has been contentious," Kley said. [Among other uncertainties,] people do not know from which lizards snakes evolved. Learning more about the feeding mechanisms of snakes may shed light on how they evolved."
Little research has been conducted on threadsnakes, in part because their small size makes them difficult to handle and study. The tendency of the threadsnake to burrow also makes it extremely difficult to find, Kley said.
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University of Massachusettes
Society for the study of amphibians and reptiles
American Society for Ichthyologists and Heprtologists
Threadsnake Feeding Videos
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