Water Moccasins vs. Water Snakes

As the largest wetland and swamp in the United States, the Atchafalaya Basin is a thriving, biodiverse environment teeming with unique species, including various fascinating snake species. The venomous water moccasin (or cottonmouth) and the harmless water snake often appear in the spotlight. Both snake species dwell in similar habitats, leading to confusion and misidentification.

Water moccasins, or cottonmouths, belong to the pit viper family, alongside rattlesnakes and copperheads. One of the few venomous snake species native to North America, they are prevalent in the southeastern United States, including the Atchafalaya Basin.

The term "water snake" describes a broader group of non-venomous snakes. These snakes populate diverse regions across North America, with species like the northern water snake and the banded water snake being common.

While water moccasins and water snakes can be similar lengths, keen observers can note critical differences in their body structures. Water moccasins are known for their thick, heavy bodies and distinctive, blocky triangular head. Unique to pit vipers, they have a facial pit between their eyes and nostrils, functioning as a heat-sensing organ.

On the other hand, water snakes native to the Atchafalaya Basin are typically more slender. Their heads smoothly blend into their bodies without a pronounced neck and lack the pit viper's heat-sensing pits. Their heads are usually oval or rounded.

When it comes to coloration, water moccasins, and water snakes differ. Water moccasins can be olive-green and brown to nearly black, often accompanied by darker crossbands. Their nickname, "cottonmouth," arises from the stark white interior of their mouths, revealed during their characteristic defensive display.

Like the northern water snake, water snakes bear a brown to gray body with dark crossbands near the head and blotches along the body. However, color variations can be extensive, making this an unreliable sole identifier. A closer look (from a safe distance!) can also reveal differences in their eyes. Water moccasins possess vertical, elliptical pupils like a cat's, whereas water snakes have round pupils. This difference, while informative, isn't the safest way to identify the type of snake you are dealing with.

The behavior of these snakes further aids in distinguishing them. Water moccasins are often sighted basking on land or floating on the water surfaces of the Atchafalaya Basin. When threatened, they exhibit an open-mouth threat display, showing their infamous "cottonmouth."

In contrast, water snakes are exceptional swimmers and spend ample time in the Basin's waters. When disturbed, they often dive into the water, swimming away swiftly. Although both species inhabit similar freshwater environments like lakes, rivers, and marshes in the Basin, there are preferences to note. Water moccasins are more likely to inhabit the Basin's brackish waters.

Next time you're on a swamp tour, keep an eye out for the different snakes you may see.