The water moccasin, or cottonmouth (Agkistrodon piscivorus), is a species of pit viper. This semi-aquatic snake occupies swamps, marshes, and river floodplains across the Southeastern United States. It is the most aquatic venomous snake in North America, requiring caution when encountered.
Defining the Danger: Venom and Effects
The danger posed by the cottonmouth stems from its potent, largely hemotoxic venom. Hemotoxins work by breaking down red blood cells and disrupting the body’s clotting mechanisms, leading to hemorrhaging and severe localized tissue destruction.
A bite typically causes immediate, severe burning pain at the injection site, followed quickly by rapid swelling (edema). As the venom spreads, the area may show significant skin discoloration (ecchymosis). Resulting tissue damage, including necrosis, can be temporary or permanent, potentially leading to loss of function.
Although fatalities are rare due to modern medical intervention, a bite is always a medical emergency requiring immediate attention. Antivenom is administered in the hospital to neutralize the toxins and halt the progression of swelling and systemic effects.
Accurate Identification of the Cottonmouth
Accurate identification is important because the cottonmouth is often confused with harmless non-venomous water snakes (Nerodia). The cottonmouth is a heavy-bodied snake with a large, distinctly triangular-shaped head, noticeably wider than its neck. This blocky appearance is due to large venom glands located toward the rear of the head.
As a pit viper, it features heat-sensing facial pits positioned between the eyes and nostrils. Its pupils are vertical and slit-like, resembling those of a cat, unlike the round pupils of most non-venomous snakes.
Behavioral cues also aid identification from a safe distance. Cottonmouths often exhibit a defensive display by coiling and opening their mouth wide to reveal the bright white lining, the origin of their common name. When swimming, they often float horizontally on the water’s surface, while non-venomous water snakes tend to swim mostly submerged.
Encounter Safety and Bite Protocol
Preventing a cottonmouth bite involves being aware of their habitats and exercising caution near water bodies in the Southeastern United States. Snakes bite defensively, so never attempt to handle, harass, or approach a cottonmouth. Wearing protective footwear, such as thick boots, in marshy areas offers a physical barrier against strikes.
If a bite occurs, the first step is to immediately call emergency medical services. While waiting for help, the victim should remain calm and still to slow the circulation of venom. Restrictive clothing or jewelry, such as rings or watches, should be removed from the bitten limb immediately, as swelling begins rapidly.
The wound should be cleaned gently with soap and water if available, and the bitten area should be kept in a neutral position. It is important to avoid outdated and harmful first aid measures, as these actions can worsen tissue damage or accelerate venom absorption:
- Cutting the wound
- Attempting to suck out the venom
- Applying a tourniquet
- Applying ice to the area