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The Difference Between a Cottonmouth & a Water Moccasin

| Updated October 19, 2017

North America is the home for only one poisonous water snake, and that is the Agkistrodon piscivorus or what Southerners have long called the “cottonmouth moccasin.” Youngsters who live around the lakes and swamps in Florida and other areas of the deep South have long identified the water moccasin and the cottonmouth moccasin as two distinct snakes; the first one poisonous and the second one deadly poisonous. They are, in fact, the same snake.

The Cottonmouth Moccasin

The cottonmouth is a fairly large, heavy-bodied snake whose average length ranges from 30 to 48 inches. When the cottonmouth moccasin feels threatened, it coils and opens its mouth preparing to strike. It is an aggressive snake and sometimes shows the same characteristics of territorial animals. It often defends a specific area and advances on intruders.

Cottonmouth Markings

The cottonmouth moccasin, a relative of the copperhead, is a pit viper. It is an easy-to-recognize snake with its triangular shaped head and elliptical "cat-eye" pupils. Its body is brown with olive and blackish markings. They have a lighter belly, but the stripes and markings go all the way across the belly. The top of its head is flat with a small number of larger scales. When its mouth opens you can see what appears to be a patch of white cotton in their throat, hence the name “cottonmouth.”

If Bitten

Around 45,000 Americans suffer snake bites each year, according to FamilyPracticeNotebook.com. Around 8,000 bites are poisonous, resulting in an average of 12 deaths each year. If you have the misfortune to be bitten by a cotton mouth moccasin—or any snake for that matter—take it seriously. The cottonmouth moccasin’s venom is powerful and can kill you. If bitten, get to the nearest emergency medical facility as quickly as possible. Contrary to lore and legend, do not use a tourniquet and do not try to suck out the venom by mouth.

Water Snakes

In many areas of the South, folks use the term water moccasin incorrectly. The snake that is so often called a water moccasin (Agkistrodon piscivorus) is just one of several water snakes (Nerodia species) that are prevalent in watery areas of the South. The best way to tell the difference is to observe their bodies. Water snakes have bodies that are slender when compared to the thick body of the poisonous cottonmouth moccasin.

Be Cautious

While the cottonmouth moccasin and the water moccasin are, in fact, the same snake, it pays to err on the safe side when dealing with snakes. If you come across a snake in a watery area, remember that the snake is in its element. You are not. Unless you are a professional, do not attempt to catch snakes. If you assume that all snakes are dangerous, you are less likely to be bitten.