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The cottonmouth (Agkistrodon piscivorus), also known as the water moccasin, gets its name from the pale, white coloration inside its mouth. Rex Lisman / Getty ImagesWhen Hurricane Florence struck North and South Carolina in September 2018, it brought more than just storm damage—floodwaters unleashed a hidden army of snakes.
Among them was the infamous and venomous cottonmouth, also called the water moccasin, which was spotted in the rising floodwaters.
Deadly Snakes of North America
The cottonmouth (Agkistrodon piscivorus), North America's only venomous water snake, is one of just four venomous species found in the U.S. alongside the rattlesnake, copperhead, and coral snake.
Mainly found in the Southeast, the cottonmouth is named for the striking white color inside its mouth. However, a Native American legend offers a more poetic explanation for the snake's name and venom.
The cottonmouth is also known by several other names, such as black moccasin, gaper, mangrove rattle, and even the ominous "water mamba."
Like the rattlesnake and copperhead, the cottonmouth is a "pit viper," using heat-sensitive organs on each side of its head to locate prey. Despite its fearsome reputation, herpetologist Jeff Beane of the North Carolina Museum of Natural Sciences explains that the cottonmouth typically only strikes when it feels threatened, despite its menacing triangular head and piercing gaze.
Despite years of research on these reptiles, Beane is still unsure of the origin of the cottonmouth's nickname "water moccasin." It's possible the name comes from the belief that these snakes move through the underbrush as silently as a person wearing moccasins.
How to Identify a Cottonmouth
Cottonmouths are hard to miss. These large water snakes typically range from 2 to 4 feet (0.6 to 1.2 meters) in length. Their heads are distinct, shaped like large triangles, and marked with dark crossbands near their nostrils. Their snouts have a pale hue, and their jowls are noticeably wide due to their venom glands.
Cottonmouths display a stunning array of colors, with some individuals showcasing striking patterns of yellow, black, and brown across their large bodies. Their crossbands create a unique, eye-catching design.
Juvenile cottonmouths often have a yellow-tipped tail, which they use to lure in prey. As they mature, however, their coloring darkens, with older adults becoming entirely black or brown.
Regional Variations of Cottonmouths
In the past, scientists classified the cottonmouth moccasin into two subspecies: the eastern cottonmouth along the East Coast and the western cottonmouth found in regions like Alabama, Texas, and the Gulf of Mexico.
Recent genetic analysis has revealed that both the western and eastern cottonmouths belong to the same species. Additionally, the Florida cottonmouth is a recognized subspecies, living primarily in the swamps of northern Florida and southern Georgia.
The habitat of the Florida cottonmouth overlaps with that of the more widespread water moccasin. Another distinct variety is the northern cottonmouth, which inhabits the Ozark region near the Missouri River.
Habitats of the Cottonmouth
If you reside in the Southeast, particularly from Florida up to southeastern Virginia, you're likely familiar with the cottonmouth. These snakes thrive in nearly all freshwater environments, such as cypress swamps, river floodplains, and wetlands.
Cottonmouths often share their habitats with nonvenomous water snakes, so it's important to exercise caution when encountering any slithering reptile in swampy areas.
Cottonmouths can be observed both during the day and night, particularly when hunting for food. You might spot them resting on rocks by the water, lounging near tree branches, or lurking in mud pools.
What Are Cottonmouths' Diets Like?
Cottonmouths primarily consume fish but are opportunistic eaters, capable of swallowing lizards, other snakes, turtles, baby alligators, and birds. The snake is also known for its high reproductive rate, with each litter containing anywhere from one to 20 young.
Cottonmouths are ovoviviparous, meaning their eggs hatch inside the mother's body and the young are born alive. Once born, the baby cottonmouths are immediately independent, with no care or protection from their mother.
Although cottonmouths are relatively common, just spotting a snake in the water doesn't automatically mean it's a cottonmouth. To differentiate them, examine their eyes. If the snake has round pupils, it’s not a cottonmouth. But if the eyes resemble those of a cat, keep your distance – it's definitely a cottonmouth.
Signs of Cottonmouth Venom Exposure
The venom of a cottonmouth is extremely toxic and capable of causing death, though fatalities are rare. Beane explains that the venom prevents blood from clotting, and as the hemotoxins spread, they break down blood cells and cause significant hemorrhaging.
The venom can result in tissue and muscle damage, internal bleeding, and intense pain around the bite site. Fortunately, antivenin is available. It’s crucial to seek immediate medical attention if bitten, as with any snakebite.
Antivenom, also known as antivenin (and sometimes pronounced as "antiveneen"), was first created in the late 1800s at the Pasteur Institute in France. The process involves immunizing donor animals, such as horses or sheep, with various snake venoms. This causes the animals to produce antibodies to fight the venom, which are then collected, purified, and used to treat humans who have been bitten by snakes.
