Water moccasins, also known as cottonmouths, are venomous snakes that are frequently mistaken for other non-venomous water snakes. This confusion arises from shared habitats and appearances. Accurate identification is important for safety.
Authentic Water Moccasin Traits
Water moccasins, scientifically known as Agkistrodon piscivorus, are pit vipers typically found in the southeastern United States, often near water bodies such as swamps, marshes, and slow-moving rivers. These snakes generally measure between 30 and 48 inches long, with some individuals reaching up to 71 inches. They possess thick, heavy bodies with keeled scales that give them a dull, non-reflective appearance. Their coloration varies from dark brown or black to olive, sometimes displaying vague darker bands that become less distinct with age.
A water moccasin’s head is distinctly blocky and triangular, much wider than its neck, due in part to large venom glands. They have vertical, cat-like pupils and a heat-sensing pit located between each eye and nostril, a characteristic of all pit vipers. When threatened, water moccasins often coil their bodies and display the bright white interior of their mouths. They also tend to swim with most of their body, including their head, on top of the water’s surface.
Non-Venomous Look-Alikes
Several non-venomous water snake species are frequently confused with water moccasins due to overlapping habitats and similar appearances. Snakes from the genus Nerodia, commonly known as water snakes, are the most common look-alikes. These include species such as the Northern Water Snake (Nerodia sipedon), Brown Water Snake, Diamondback Water Snake, and Plain-bellied Water Snake. They are semi-aquatic and found in similar environments.
Water snakes typically have dark coloration, often with bands or blotches, which can lead to misidentification, especially when they are wet or older and their patterns fade. While they can reach considerable lengths, their bodies are generally more slender compared to the heavy-bodied water moccasin. When water snakes feel threatened, they may flatten their heads and bodies to appear larger and more intimidating, mimicking the triangular head shape of a venomous snake. They may also release a foul-smelling musk as a defensive behavior.
How to Tell Them Apart
A primary difference lies in their pupils: water moccasins have vertical, slit-like pupils, similar to a cat’s eye, while non-venomous water snakes have round pupils. Water moccasins possess a distinctly blocky, triangular head that is noticeably wider than their neck, whereas water snakes have more streamlined heads that are often the same width as their neck, even when flattened defensively. Water moccasins also have heat-sensing pits between their eyes and nostrils, a feature absent in non-venomous water snakes.
Water moccasins often swim with most of their body floating on the surface of the water. In contrast, non-venomous water snakes typically swim with most of their body submerged, with only their head visible above the waterline. Water moccasins generally have very thick, heavy bodies and short, thick tails, while water snakes tend to be more slender with longer, thinner tails for their length. The banding patterns on water moccasins, when visible, are often wider at the bottom than the top, resembling hourglasses or pyramids from above, unlike the more squarish blotches or uniform bands found on many water snakes.
What to Do When You See a Snake
When encountering a snake, maintain a safe distance and avoid sudden movements. Snakes typically do not seek to attack humans and will often try to escape if given the opportunity. Allowing the snake to move away on its own is generally the safest course of action.
Never attempt to handle, capture, or harm a snake, even if it appears to be dead, as some snakes can still bite due to reflex actions. If a snake is found in an undesirable location, such as a yard or home, it is best to contact local animal control or a wildlife expert for safe removal. Taking a photograph from a safe distance can be helpful for identification if professional assistance is needed.