Frontlines | The Herpetological 'Hand'
Courtesy of Gene Ott
Snakes cannot properly wear gloves, but cottonmouths do exhibit some form of "handedness," says Eric Roth, a zoologist at the University of Oklahoma. In a recent study Roth demonstrated that the adult female snakes show a tendency to coil clockwise, with the left side of their bodies on the inside of the coil.1
Roth questions whether brain lateralization or other physiological asymmetry, such as the alignment of internal organs, determines coiling preference. Researchers have shown that brain lateralization, once thought to be unique to humans, controls behavioral asymmetry in many vertebrates, including other primates, toads, and fish, which exhibit limb or fin preference.
Animals with lateral vision display asymmetrical eye use, which is directly related to neural asymmetries. The right eye detects prey, while the left eye detects predators, explained animal behaviorist Lesley Rogers, University of New England, Australia, in an E-mail. "It is likely to be true in snakes."
"Other asymmetries (e.g., in the internal viscera) could contribute to asymmetric coiling," wrote psychobiologist Giorgia Vallortigara, University of Trieste, Italy. "Nonetheless, considering the evidence in other reptiles ... I think it is very likely that snakes have lateralized brains at some level."
Roth says that he chose the cottonmouth because it is a good model for studying various aspects of wetland ecology. Besides, he adds, it has a "cute face and bright smile."
--Maria W. Anderson