The Water Moccasin, scientifically known as the Cottonmouth (Agkistrodon piscivorus), is a venomous semi-aquatic pit viper found across the Southeastern United States. This reptile is often shrouded in myth, leading to questions about its true range and safe identification. The common name “Water Moccasin” suggests a habitat near water, contributing to confusion with many harmless species. Understanding its genuine presence and characteristics is important for public safety.
Confirmation of Presence and Specific Range
The answer to whether Water Moccasins are in Oklahoma is definitively yes. The subspecies found in the state is the Western Cottonmouth (Agkistrodon piscivorus leucostoma). Their distribution is not statewide, but concentrated in the eastern and southern portions of Oklahoma.
The population is primarily confined to the eastern third of the state, particularly within the Coastal Plain and Ouachita Mountain regions. Cottonmouths are frequently encountered along major river systems, floodplains, swamps, and sluggish backwaters. They are closely tied to permanent water sources, meaning they are rarely found in the arid western plains of Oklahoma.
Identifying the Cottonmouth
The Cottonmouth is a heavy-bodied snake that typically appears much thicker and more robust than most non-venomous aquatic snakes. As a pit viper, it possesses a distinct, blocky, and triangular-shaped head that is noticeably broader than its neck. This difference in head-to-neck width is a reliable physical identifier, though some non-venomous snakes can flatten their heads when threatened.
The snake’s venomous nature is indicated by the presence of a deep, heat-sensing pit located between the eye and the nostril. The pupils of the eye are vertically elliptical, resembling a cat’s eye in bright light. Adult coloration is highly variable, ranging from dark olive or brown to a nearly uniform black, often obscuring the faint dark crossbands that are more prominent in juveniles.
The most well-known behavior is the defensive display that gives the snake its name. When threatened, the Cottonmouth will often coil its body and gape its mouth widely to reveal the pale, cottony-white lining inside. This is a clear warning sign. Unlike many non-venomous snakes that flee immediately, the Cottonmouth often holds its ground. They are semi-aquatic and are often seen basking on logs, branches, or rocks near the water’s edge.
Harmless Look-Alikes in Oklahoma
A significant amount of confusion stems from the presence of several species of non-venomous watersnakes (Nerodia) that share the Cottonmouth’s habitat and dark coloration. In Oklahoma, this includes species like the Northern Watersnake, Plain-bellied Watersnake, and Diamond-backed Watersnake. These harmless snakes are frequently misidentified and unnecessarily killed due to their aquatic nature and similar size.
A key difference is the shape of the eye pupil, as Nerodia species have round pupils, unlike the vertical slits of the Cottonmouth. Watersnakes also lack the deep facial pit organ that characterizes all pit vipers. While watersnakes can be large and heavy-bodied, their heads are typically narrower, and their eyes are visible when viewed from directly above, which is not the case for the Cottonmouth.
When watersnakes feel cornered, they may also exhibit defensive behaviors, including striking repeatedly and releasing a foul-smelling musk. However, they do not display the stark, white mouth interior characteristic of the Cottonmouth. The vast majority of snakes encountered in or near water in Oklahoma are these non-venomous watersnakes.
Encounter Safety and Prevention
Minimizing the risk of encountering any snake begins with awareness of the environment. When navigating areas near water in the eastern part of the state, wear thick, high-top boots and long pants. Avoid reaching into or stepping over thick brush, rock crevices, or dense vegetation near riverbanks without first visually inspecting the area. Snakes are not inherently aggressive and will typically attempt to retreat, so maintaining a safe distance of at least six feet is advised upon sighting.
If a bite occurs, remain calm and seek professional medical attention immediately. The affected limb should be kept still and positioned at or below the level of the heart to slow the spread of venom. Remove any constrictive clothing or jewelry from the area before swelling begins. Do not attempt to suck out the venom, cut the wound, or apply a tourniquet, as these actions can cause more harm than good.