The snakes’ aggressiveness has been greatly exaggerated, says Arlington-based reptile expert Micheal Smith. Photo by Michael Smith.

July 23, 2020

In an episode in The Lonesome Dove, a fellow falls into a river and is immediately attacked by a swarm of snakes. Many people tell a similar story, of some poor soul who falls into a “nest” of cottonmouths and dies from hundreds of venomous bites. Boaters and fishermen will also tell you that this snake will chase you down the dock or away from your fishing spot. What a monster it must be! 

The cottonmouth, or “water moccasin,” is a chunky snake of marshes, rivers and nearby bottomland forests. I have met many of these serpents in my wanderings as a naturalist and have never been attacked. In fact, bites from cottonmouths are not common, according to Andrew Price’s excellent field guide Venomous Snakes of Texas,  and death from snake bite is rare. 

According to Texas Parks and Wildlife Department, a small percentage (7 percent) of snakebites in Texas each year involves this species. Also, according to the National Safety Council, a person is 5 times more likely to killed by lightning (odds are 1 in 4,210,857 per year) than by snakebite (odds are less than 1 in 20,406,462). 

These snakes are dangerous if accidentally stepped on or picked up, but unless you do those things, there’s not much need for worry. If you see one, just step away from it. Chances are it will stay put, or maybe crawl away from you.

Sometimes a cottonmouth will move toward you, but the explanation is almost always that it was headed some place it thought would be safer and not paying attention to what is in the way (that would be you!). When you step to the side, the snake crawls or swims on past you.

Cottonmouth snake The cottonmouth gets its name from its white gaping mouth, which it opens to scare off threats. Photo by Michael Smith.


In and around water, the snake most often seen by Texans is the water snake, a harmless but feisty species not related to the cottonmouth. Over the years I have caught many of these snakes, and the snake interprets this as a life-and-death attack and so it usually bites. Their rows of tiny but sharp teeth leave nothing but scratches. 

In spring, more than one male water snake will court a female, and people sometimes find several of them in the water, swimming and twisting around each other. That is the closest you will get to finding a “nest,” and they are not even cottonmouths!

How do you know which one you are seeing? If it floats high in the water as it swims, it is more likely to be a cottonmouth (however, these snakes can swim underwater). The body of a water snake tends to sink lower in the water. 

What about head shape? When frightened, water snakes flatten out, and as a result their heads will have a triangular shape. However, water snakes have eyes set fairly high on the head, with big round pupils, while the cottonmouth’s eyes are set lower on the face and their pupils are elliptical or “cat-eyed” (except at night when they may open to let in more light and appear rounded). The lip scales of water snakes have evenly-spaced thin dark bars, unlike cottonmouths. What you ought to keep in mind is that if you are close enough to check the pupils of the eyes or the facial pattern, perhaps you would be better off taking a couple of steps back. 

I said that bites from cottonmouths are uncommon, but don’t tempt fate! 

Michael Smith with cottonmouth snakeMichael Smith photographs a cottonmouth. Photo by Carl Franklin.


One of my encounters with cottonmouths happened in East Texas with Carl Franklin, the former curator and collections manager at the University of Texas at Arlington’s Amphibian and Reptile Diversity Research Center. 

A chunky, dark ribbon of snake was at the roadside, and we piled out to say “hi.” Carl took a picture of me photographing the snake, while the snake used the defense for which it is famous: he gaped his mouth open, not trying to bite but just displaying his folded fangs and pale white mouth. It is a sort of warning that may startle an enemy. 

After a few photos I got him off the road, for his own safety. While being pushed and prodded with a stick, he never offered to bite.


What if you are bitten and you think it was a cottonmouth? The first thing to do is to move away from the snake. Do not worry about killing it and taking it to the hospital; they do not need to see the snake in order to treat you. Immediately take rings and watches off because a cottonmouth bite will cause swelling right away. There are some very important things NOT to do, according to the Wilderness Medical Society:

1.Do not cut at the bite location and try to suck venom out

2.Do not apply a tourniquet or pressure bandage

3.Do not pack the bite in ice or apply electricity to it

4.Do not take alcohol, pain killers (like aspirin), or other drugs 

These things have been found to be unhelpful and may make things worse. Here is what you should do and do it quickly: go to a hospital emergency department for treatment.

Keep in mind that your chances of being bitten are very low. Wildlife educator Orry Martin has a YouTube video in which he tries every which way to get cottonmouths to chase or attack him. Check it out! It should show once and for all that these monsters are not monsters at all.

Wildlife educator Orry Martin humorously debunks the myth that cottonmouths will chase you.

Chased By A Nest of Cottonmouths

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