Know your nature: Water moccasin

Story + Illustration by Michele Roldán-Shaw

Water Moccasin (Agkistrodon Piscivorus)

The water moccasin, or cottonmouth, is the most dreaded snake in the South. Lurking in coils around swamps or gliding silently through blackwater, these pit vipers with their thick bodies, dark color, blocky triangular heads and slitted cat-eyes have an undeniably sinister look. But that is just our primal heritage warning us to steer clear. Deadlier than copperheads, though not as deadly as rattlesnakes, moccasins are capable of delivering a potent, tissue-destroying venom that will send you to the ER.

Yet almost nobody will die from them. Let’s be real: you have a much greater chance of getting killed in a car wreck or falling down dead in your house from a heart attack. According to statistics from the University of Florida, your chances of dying from snakebite in the U.S. (where antivenoms are readily available) are about one in 50 million, nine times less likely than getting struck by lightning. The poison this creature carries is meant for the frogs, fish, birds, lizards, small turtles and baby alligators it likes to eat. Moccasins will even cannibalize each other, but they don’t have a taste for you.

The aggressiveness of the water moccasin has been greatly exaggerated. When threatened, it might respond by coiling its body and displaying its fangs, but usually it will bite only if you try to pick it up.

How the moccasin got its (other) name

The name cottonmouth comes from a gaping display these snakes do when threatened, which exposes the arrestingly bright white lining of their mouths. They also might flatten out their bodies to appear bigger, or eject a pungent odor from their anal glands. They try their best to make you go away without a fight. With their heavy bodies, they can’t flee as readily as faster snakes and are therefore more likely to stand their ground; but contrary to popular belief, they are not aggressive and won’t strike unless cornered, stepped on or picked up.

The scientific name translates roughly from the Greek as “hook-toothed fish-eater.” This is the world’s only semiaquatic viper, found in nearly all freshwater habitats of the South, especially cypress swamps, blackwater rivers and floodplain forests. They are not at home in swift, cold or salt water, and they don’t stray much more than a mile or two onto dry ground. Ranging from the Great Dismal Swamp of Virginia, south down the length of Florida, through all the Dixie states and as far west as Texas, even north into the Ohio River Valley, the moccasin is very present here in the Lowcountry (although you won’t typically see them in salt marshes.) Often confused with nonvenomous water snakes that have similar drab coloring and indistinct patterns, cottonmouths can be identified by their triangular heads, which give way to thin necks before widening out into massive bodies, then suddenly becoming small again at the tail. By contrast, water snakes are uniformly slender and don’t have a distinct neck. An even more foolproof way to distinguish the two is that pit vipers have elliptical pupils, whereas harmless snakes have round ones, but who wants to get that close.


Hot weather is the moccasin’s time. They are most active at night but can be found sunning and slithering throughout the day. In droughts, they congregate around shrinking pools to feed on frogs and fish that get trapped there. Despite stories of them dropping from trees, they are not big climbers and tend to stay at ground level; it’s mostly the harmless water snakes that hang from higher branches. Moccasins are strong swimmers and have even been spotted in the ocean—although they are not true sea snakes—a trait that has allowed them to colonize barrier islands off the Atlantic and Gulf coasts. Unlike other water snakes that swim with only their heads poking up, moccasins are very buoyant and will travel along with most of their bodies above the surface. They can attack underwater.

Interestingly, baby cottonmouths don’t hatch from eggs but are born live and up to a foot long. The mother abandons them immediately, but they don’t really need her because in addition to being big, they are already well equipped to catch their own prey, with bright yellow tail tips that are wriggled as lures. Baby cottonmouths have fancier colors and more distinct banding patterns that tend to fade as they age into the drab brownish-grayish-black of adults.

As with all wild creatures, particularly the dangerous ones, the best policy is to leave moccasins alone. Admire them from a distance; or if you don’t admire them, at least don’t try to kill them. More people get bit attempting to destroy poisonous snakes in the belief it will keep their surroundings safe, which is especially sad when they misidentify and kill the harmless ones. Snakes just want to be happy in their own snakey way — they don’t want trouble and if given the chance, will usually just slip off never to be seen again. Goodbye and good luck, Mr. Snake!