When you see a snake, your first instinct may be to run, no matter the kind. However, many snakes, such as the watersnake, aren’t harmful and even contribute positively to their surrounding environments. Others, such as copperheads, look similar but can cause a lot of harm. 

The main differences between a cottonmouth and a watersnake lie in the shape of the head and pupils. In addition, cottonmouths maintain one indent, sometimes called a pit, on each side of their head. Watersnakes, on the other hand, don’t have pits. 

While these two snakes are pretty similar, they have some major differences. This article will examine the primary differences between the cottonmouth and watersnake to help you know what you’re dealing with in case you encounter any of the two. Let’s get started. 

Key Differences Between Cottonmouths and Watersnakes

At first glance, these snakes look pretty similar. Unless you get up close and personal – and you probably don’t want to – the best course of action may be to run either way. However, if you’re the type that kills venomous snakes simply for their existence, it’s best to do some research first. After all, watersnakes are harmless. 

Below is a table that summarizes the similarities and differences between Cottonmouths and Watersnakes.

	Cottonmouths	Watersnakes
Color	> Tan or light brown interspersed with red when young.  > Dark brown or dark gray as adults.  > Eye stripe on head.	> Multiple colors, including brown, gray, red, green, and tan.  > Solid – usually without bands.
Head Shape	> Large heads. > Square shape. > Head pits.	> Round and flat head.  > No head pits.
Pupils	Oval and slit pupils.	Round full pupils.
Environment	Found near water	Found near water

While this table is an overview, it doesn’t give you a lot of information. To identify which snake you’re dealing with, however, you’ll need all the details. Let’s look at each in more detail below. 

Color

Cottonmouths and watersnakes have very similar coloration. Most of the time, snakes can be differentiated by simply glancing at the head shape and coloration. With these two, however, you may have a hard time differentiating based on color. 

Still, there are a few differences in color, especially when the snakes are young. Let’s take a look. 

Cottonmouths, sometimes called water moccasins, are easily confused with watersnakes, both because of the cottonmouth’s similar nickname and markings. Traditionally, cottonmouths come in similar colors – dark brown or dark gray. There’s not a lot of variation as adults. On the other hand, Watersnakes come in a range of different colors, though many of them are black or brown. 

Because they’re so similar as adults, it’s nearly impossible to tell the difference with a quick cursory glance. After all, unless you’re a professional snake wrangler, you’re probably running for the hills as soon as you catch sight of one of these. 

When they’re young, however, you have a better chance of telling them apart through color. 

Young cottonmouths typically have a distinct tan color. The tan can be intermixed with red-brown crossbands, and they may even have a bit of yellow tossed through their tails. 

Watersnakes stay fairly consistent in their coloration throughout their life. With this in mind, if you see a young dark brown or gray snake near the water, it’s much more likely to be a watersnake than a cottonmouth. Watersnakes may also be olive green, red, or occasionally tan. However, more often, they develop in darker shades. 

So, while it’s not impossible to tell these two snakes apart through coloration alone, it will not be easy either. With some experience, however, you’ll soon be identifying these two with no issues. 

Head Shape & Features

After color, the next thing you’d want to look at is the shape of the head. Almost universally, nonvenomous snakes have flat heads that are rounded around the edges. Venomous snakes, on the other hand, nearly always have large square or boxy heads. 

The cottonmouth and the watersnake aren’t exceptions to this rule, which may be the easiest way to tell them apart – that is, if the snake pauses long enough for you to get a good look at its head.

Often, these slippy slithers move far too quickly for amateur enthusiasts to get a good look. However, both snakes are prone to sunbathing, so you may find it easier than you initially assumed. 

First up, the cottonmouth. This snake, as we discussed, has a large square head. Think of it as the more handsome of the two snakes – a chiseled jaw and clearly defined features. The head of the cottonmouth almost appears separated from its body, whereas the watersnake tends to have a fully blended body.

In addition to its head shape, the cottonmouth has distinct indents, sometimes called pits, on the side of its head. You probably won’t see this initially, but if you get the chance to see one while sunbathing, you should notice this feature fairly quickly. 

Now for the watersnake. Watersnakes have rounded, flattened heads, like most nonvenomous snakes. The body of the watersnake blends into the head, and if you aren’t paying close attention, you may not even notice the head up front. 

Unlike cottonmouths, watersnakes do not have pits in their heads. Their heads are also significantly smaller than cottonmouths. This is one of the reasons it’s so much easier to identify them through head shape than color. 

One other head feature I want to mention is eye stripes. Cottonmouths always have an eye stripe on their head. Watersnakes can have this feature, but they don’t always. If you notice the eye stripe combined with the boxy head, it’s almost guaranteed to be a cottonmouth. 

Pupils

The pupils of these two snakes are almost as distinct as their heads. As with the head shape, venomous and nonvenomous snakes have very different pupils. 

Watersnakes, because they aren’t venomous, have round pupils. While it may be difficult to see unless you’re close to the snake, you’ll quickly notice that the pupils seem to take up the entire eye on this snake. This is a sure sign that you’re dealing with a watersnake or another nonvenomous snake.

Cottonmouths, on the other hand, have slitted pupils – perhaps because they are predators. Similar to cats, the pupils are long and oval-shaped. 

Pupils are, by far, the most certain way to tell the difference between these two snakes, but it isn’t the easiest way because you have to be so close.

Environment

Unfortunately, these two snakes live in the same environment, so this isn’t a reasonable way to identify the differences between the two. However, it’s still helpful to know. 

Both snakes live all over North America and congregate near the water. However, watersnakes tend to spend more time in the water than cottonmouths – hence their name. 

Cottonmouths spend their time moving between tall grasses and leafy plants that often grow near the water. While they can sometimes be found in the water, they don’t enjoy swimming quite as much as their watersnake cousins. More likely, you’ll find them slithering through grasslands and forests nearby. 

Watersnakes, while they can be found basking close to water bodies, are more likely to be seen sitting in shallow water underneath trees or somewhere similar. 

Final Thoughts

Cottonmouths and watersnakes are very similar snakes, which makes it hard to tell the difference, especially if you aren’t too close. The easiest way to tell the difference is by looking at their head shape or pupils. These are the most distinct features of both.

Always show caution when not sure whether you’re dealing with venomous or non-venomous snakes. Venomous snakes will almost always show threat displays, such as opening their mouth, and this is another helpful way to tell them apart.

Know the difference between these two, and save the life of a watersnake.