How To Tell A Cottonmouth From A Water Snake?

You may have heard that any snake swimming in the water is dangerous and should be avoided at all cost. While this isn’t entirely correct, it is true that cottonmouth snakes, which spend much of their time in the water, are highly venomous. That said, most water snakes are completely harmless; so, how can you know which type of snake you’re dealing with? Keep reading! In this article, we’ll talk about how to tell a cottonmouth from a water snake. 

What is a Cottonmouth?

What is a Cottonmouth

Cottonmouth snakes, also known as water moccasins, can be found throughout the southeastern United States. They are found primarily in wetland regions such as ponds, lakes, streams, and swamps, though they sometimes venture into drier habitats as well.

Cottonmouths are mostly dark, though as juveniles they are a lighter brown in color with speckled reddish crossbands along their body and bright yellow tail tips. As they mature their entire body darkens to dark brown, dark gray, or even black, the yellow tail tip disappears, and very little of the body pattern remains.

Cottonmouths are medium to large snakes, averaging 2 to 4 feet in length with thick, heavy bodies. They are excellent swimmers that spend nearly as much time in the water as they do on land.

Cottonmouths are a species of pit viper; as such, they have a distinctive pit on each side of the face between the eye and nostril. This pit allows them to sense the body heat of potential prey.

Like all pit vipers, cottonmouths are venomous. Their venom destroys bodily tissues, killing their prey and causing serious injuries in any human they bite.

What is a Water Snake?

What is a Water Snake?
Water Snake

The term water snakeapplies to a variety of non-venomous snake species and subspecies. These water-loving reptiles can be found throughout North America, though they are most populous in southern and eastern parts of the United States.

Because there are different species of water snakes, they don’t all look the same. Some are brown or gray, while others are reddish, olive green, or tan in color.

Most water snakes have visible markings and patterns on their bodies, though not all. The red-bellied water snake, for example, is a solid dark gray except for the red scales along its belly.

Cottonmouths come in different sizes depending on their species; some only grow a foot or two long, while others can grow up to 5 feet long. They are generally long, slender snakes with a ridge along their back.

Water snakes tend to stay close to the water; sometimes they will climb into trees and rest on branches, quickly dropping down into the water below if they are disturbed. They do most of their hunting in the water.

As mentioned, water snakes are non-venomous, and their bite poses little or no threat to humans. That said, the saliva of some species does contain enzymes that can have venom-like effects on their prey.

Cottonmouth Vs. Water Snake: How to Tell the Difference

Cottonmouths and water snakes are often confused since they both swim and sometimes have similar coloring. But cottonmouths are venomous and water snakes are not; therefore, it’s important that you learn to tell the difference between them–especially if you have both kinds of snakes living in your area.

Let’s talk about some of the best ways to tell cottonmouths apart from water snakes:

  • Head shape: Cottonmouths tend to have a large, blocky, triangular-shaped head. On the other hand, most water snakes have a smaller, smoother, more rounded head.
  • Eyes: Cottonmouths have classic pit viper eyes; they have narrow, slit-like pupils and slanted brows that make them look like they have a built-in frown. Meanwhile, water snakes have round pupils and no distinctive brow ridge.
  • Body thickness: Cottonmouths have a thick, stocky appearance relative to their length. Water snakes are generally longer and thinner, with a more slender, streamlined appearance.
  • Pits: Cottonmouths are pit vipers, so they have the classic heat-sensing pits between their eyes and nostrils. Water snakes belong to a different family of snakes, so they don’t have these pits. Of course, if you’re close enough to spot the pits on a snake’s face, you’re close enough to get bit; it’s best to retreat to a safe distance immediately.

Check out this video to learn more about telling cottonmouths apart from other water snakes:

Is a Cottonmouth and a Copperhead the Same Snake?

Another snake commonly confused with the cottonmouth is the copperhead. Perhaps this is because they have similar sounding names and tend to be found in many of the same regions.

They are both pit vipers, and as such, they are both venomous. However, cottonmouths and copperheads are two different kinds of snakes

Copperheads tend to be lighter in color than cottonmouths, and they have a distinctive dark brown hourglass pattern on their back. As the name suggests, they usually have a copper-colored head.

Like cottonmouth juveniles, young copperheads also have bright yellow tails that fade as they mature.

Copperheads are land-dwelling snakes; though they may be found living near water sources, they don’t spend a lot of time in the water.

Though copperheads are venomous, cottonmouths are considered to have the more dangerous venom. That said, if you are bit by either snake, you should get to the hospital immediately to receive proper medical treatment.


Cottonmouths and water snakes both live near the water and are both excellent swimmers; what’s more, they are both found throughout much of the U.S. southeast. Learning to tell these two snakes apart is important since cottonmouths are venomous and water snakes are not.

1 thought on “How To Tell A Cottonmouth From A Water Snake?”

  1. You’ve got this paragraph: “Cottonmouths come in different sizes depending on their species; some only grow a foot or two long, while others can grow up to 5 feet long. They are generally long, slender snakes with a ridge along their back.”

    I’m wondering if you’ve conflated the two snakes in this paragraph. Cottonmouths are NOT long and slender; they’re thick-bodied.


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