The cottonmouth snake, also known as the water moccasin, is one of the most notorious venomous snakes in North America. Found primarily in the southeastern United States, this large, aquatic snake is easily recognizable by its distinctive white mouth, which it often displays as a warning when threatened. While cottonmouths play an important role in their ecosystems, they are also a serious threat due to their potent venom. The cottonmouth, also known as the water moccasin, is named for the white color inside its mouth, which it reveals when defending itself. Two species of the Agkistrodon genus inhabit the U.S.: the cottonmouth and the copperhead, both of which can be found in North Carolina. The subspecies present in the state is the Eastern cottonmouth (Agkistrodon piscivorus piscivorus). As a member of the viper family, the cottonmouth’s venom toxicity is ranked fourth among North Carolina’s six venomous snake species, behind the coral snake, eastern diamondback rattlesnake, and timber rattlesnake.
When Hurricane Florence swept through North and South Carolina in September 2018, the devastation caused by wind, rain, and flooding wasn’t the only danger residents had to contend with. The floodwaters brought with them a hidden threat: snakes. Among them, the infamous and venomous cottonmouth snake (also known as the water moccasin) emerged from hiding, posing a serious risk to those in affected areas.

What is a cottonmouth snake?

The cottonmouth (Agkistrodon piscivorus) is a venomous water snake native to North America, and it is one of the four venomous snake species found in the United States. The others include the rattlesnake, copperhead, and coral snake. The cottonmouth is easily recognized by its signature white mouth lining, which it exposes when threatened—a behaviour that likely inspired its name. The snake also goes by other names, including black moccasin, gaper, and water mamba, with regional variations depending on where it is found.
As a member of the pit viper family, the cottonmouth possesses heat-sensitive “pits” on either side of its head, which it uses to detect prey in low-light conditions. While cottonmouths are often considered aggressive due to their tendency to stand their ground, experts such as herpetologist Jeff Beane explain that these snakes generally only bite when they feel directly threatened.

Physical appearance of a Cottonmouth

Cottonmouths are large, ranging from 2 to 4 feet (0.6 to 1.2 metres) in length, with thick bodies and wide, triangular heads. They often have dark crossbands near their nostrils, and their snouts are typically pale in colour. Their venom glands contribute to their notably large jowls. Cottonmouths can appear in a variety of colours, from dark brown to almost black, and they may display crossbands of yellow, black, and brown. Juveniles are particularly striking, often featuring a bright yellow tip on their tail, which they use to lure prey. As they mature, the yellow tail fades, and their bodies become darker. Cottonmouths have facial pits between their eyes and nostrils that help them sense heat and strike prey.

Regional variations of the cottonmouth

While there was once debate about whether the cottonmouth should be divided into distinct subspecies, recent genetic studies have shown that the various forms of cottonmouths are actually all part of a single species. Historically, there were distinctions between the eastern cottonmouth (which inhabited the eastern U.S.) and the western cottonmouth (found in states like Alabama, Texas, and along the Gulf Coast). There is also a recognized Florida cottonmouth that occupies a small range in northern Florida and southern Georgia swamps, as well as a northern cottonmouth found around the Ozark region near the Missouri River.

Habitat of the cottonmouth

Cottonmouths are primarily found in the southeastern United States, from Florida to southern Virginia, and they prefer freshwater habitats like swamps, river floodplains, and wetlands. These areas are often shared by both venomous and nonvenomous water snakes, so it’s essential to exercise caution when encountering any snake in these environments. Cottonmouths can be seen both during the day and at night, hunting for food or resting near the water’s edge or in trees. They are adept swimmers and can often be found lounging on rocks, tree branches, or in muddy pools.

Diet of the cottonmouth

Cottonmouths are opportunistic feeders with a broad diet. While they primarily eat fish, they will also consume lizards, other snakes, turtles, baby alligators, and even birds. They are ovoviviparous, meaning their eggs hatch inside the mother’s body, and the young are born live. Each litter can contain anywhere from one to 20 babies. After birth, the young snakes are left to fend for themselves, as the mother offers no care.

How to identify a cottonmouth?

While cottonmouths are common in their habitats, it’s important to remember that not all water snakes are cottonmouths. One way to identify a cottonmouth is by looking at its pupils—if they are slit-shaped (resembling a cat’s eyes), it’s a cottonmouth. If the snake has round pupils, it is not a cottonmouth. It’s always safest to avoid approaching or handling any snake you encounter.

Cottonmouth venom and its effects

Cottonmouth venom is highly toxic, containing hemotoxins that prevent blood from clotting, leading to hemorrhaging, muscle tissue damage, and internal bleeding. Although fatalities from cottonmouth bites are rare, the bite can be excruciating and result in severe pain, swelling, and tissue damage around the wound. In extreme cases, the venom can cause permanent damage to limbs or organs. Fortunately, there is an antivenin available, and if bitten, it’s critical to seek medical attention immediately.

Cottonmouth snakes role in their ecosystems

While cottonmouth snakes play an important role in their ecosystems by controlling fish and rodent populations, their venomous bite makes them a dangerous species to encounter. Whether you live in their habitat or are simply visiting, it’s essential to be aware of the signs of a cottonmouth and know how to react if you spot one. If bitten, immediate medical treatment is crucial to prevent serious complications. Always remember, while these snakes may appear threatening, they are generally not aggressive unless provoked.
Cottonmouth snakes are vital for maintaining balance in their ecosystems but can pose a serious risk due to their venom. They are not usually aggressive unless threatened, so it’s best to admire them from a distance and avoid provocation. Always stay cautious in their habitats to ensure safety.
Also Read | List of animals whose sounds can be heard from miles away