The water moccasin, known widely as the Cottonmouth (Agkistrodon piscivorus), is North America’s only venomous water snake, inhabiting the swamps and waterways of the southeastern United States. This semi-aquatic pit viper is a source of considerable public fear. The question of whether this snake can deliver a bite while submerged is a common concern that impacts how people interact with its environment.
The Mechanics of Underwater Biting
The popular belief that a water moccasin cannot bite underwater without drowning is a myth; these snakes are perfectly capable of biting while submerged. As a semi-aquatic predator, the water moccasin regularly hunts and captures prey like fish and amphibians beneath the surface. Their jaw and respiratory systems are adapted to allow them to open their mouths and strike without risking water inhalation.
A bite deep underwater is a rare event, typically occurring only when a snake is secured, such as when it is accidentally stepped on or pinned in shallow water. Most bites occur when the snake is near the surface, partially submerged, or on land, where it has stable leverage.
Identifying the Cottonmouth
Correctly identifying the Cottonmouth is important, as it is often confused with harmless non-venomous water snakes, such as those from the Nerodia genus. The water moccasin is characterized by a thick, heavy body and a distinctly blocky, triangular head. This head shape is a result of large venom glands, making the neck noticeably narrower than the head.
These pit vipers possess vertical, elliptical pupils and have heat-sensing pits located between their eyes and nostrils. When swimming, the Cottonmouth typically holds its body and head elevated, riding high on the water’s surface, whereas non-venomous water snakes usually swim mostly submerged. When threatened, the snake will often gape its mouth, revealing the bright white lining that gives it the “Cottonmouth” nickname.
Understanding Behavioral Triggers
Water moccasin bites are overwhelmingly defensive, contrary to the myth of an aggressive snake actively pursuing humans. Studies indicate that when approached, the snake’s primary reactions are to flee or to engage in a threat display. This defensive posture involves coiling the body, vibrating the tail, and exposing the white mouth lining as a clear warning.
Bites usually result from a person accidentally stepping on the snake, attempting to handle it, or cornering it in a confined space. Even when a strike occurs, the snake may deliver a “dry bite,” injecting little or no venom to conserve its venom for prey.
Emergency Response
If a water moccasin bite is suspected or confirmed, immediate action is necessary, beginning with calling emergency services. The bitten individual should move away from the snake and remain as calm and still as possible to slow the spread of venom. It is important to remove any rings, watches, or tight clothing from the affected limb before swelling begins.
The wound should be gently cleaned with soap and water and covered loosely with a clean, dry dressing. The bitten limb should be kept immobile and positioned at or below the level of the heart. Actions to avoid include:
- Applying a tourniquet.
- Cutting the wound.
- Attempting to suck out venom.
- Applying ice.
These measures can cause more harm than good and delay appropriate medical treatment.