Cottonmouths, scientifically known as Agkistrodon piscivorus, are a type of venomous snake native to the southeastern United States. These semi-aquatic reptiles inhabit a variety of wetlands, from swamps and marshes to slow-moving streams and ponds. Understanding their characteristics is important for safety.
The Question of the Rattle
Cottonmouths do not possess a rattle on their tail. The distinctive, segmented rattle is a feature unique to rattlesnakes, which belong to the genera Crotalus and Sistrurus. The confusion often arises because both cottonmouths and rattlesnakes are venomous pit vipers, sharing some general characteristics like a robust body and a somewhat triangular head. While they lack a rattle, cottonmouths employ a different, equally striking defensive display when threatened.
Telling Cottonmouths and Rattlesnakes Apart
The most definitive physical characteristic distinguishing a cottonmouth from a rattlesnake is the tail. Rattlesnakes are easily identified by the presence of a rattle, a series of interlocking segments made of keratin, at the end of their tail. In contrast, a cottonmouth’s tail tapers smoothly to a point, lacking any such structure. Both species are pit vipers, meaning they share features such as heat-sensing pits located between their eye and nostril, and elliptical, cat-like pupils. While rattlesnakes often vibrate their tail and produce a rattling sound as a warning, cottonmouths exhibit a different kind of defensive behavior.
Identifying a Cottonmouth
They have a heavy, muscular body with a broad, somewhat triangular head that is distinctly wider than their neck. Their coloration can vary significantly, ranging from dark brown or black to olive, with some individuals, particularly juveniles, exhibiting distinct banded patterns. A defining characteristic is the dark band that extends through the eye, often bordered by lighter lines above and below.
When threatened, a cottonmouth will often perform its characteristic defensive display, opening its mouth wide to reveal a stark white, almost cotton-like, interior. This behavior, from which they derive their common name, serves as a clear warning to potential predators. They also may coil their body and vibrate their tail.
Cottonmouths prefer aquatic or semi-aquatic habitats, including swamps, marshes, and the edges of ponds and slow-moving streams. Another key identification cue is their unique swimming style; cottonmouths swim with most of their body floating on the surface of the water. This differs from many non-venomous water snakes, which swim with only their head visible above the waterline. Being venomous, a cottonmouth bite requires immediate medical attention, underscoring the importance of recognizing these snakes and giving them space.