With so many snake species calling our planet home, it’s often easy to confuse them with one another. This is often the case with copperheads and cottonmouths. Due to their physical similarities, people often have difficulty telling them apart, although, in reality, they’re vastly different species.

Cottonmouths and copperheads are both pit vipers and by far the most common venomous snakes in the U.S. Though somewhat similar in size and coloring, cottonmouths prefer wet, marshy areas. In contrast, copperheads live in dry, rocky environments.

Throughout this article, I’ll address the subtle and not-so-subtle differences between copperhead snakes and cottonmouths. This will make it easy for you to tell them apart and help you learn new, fun facts. Let’s start!

The Main Differences Between Copperhead Snakes and Cottonmouths

Although it can be easy to mix up these two dangerous vipers from the Agkistrodon genus at first, there are quite a few key differences between them. The most significant ones include: 

• Geographic location
• Habitat
• Appearance 
• Venom level and strength

The table below summarizes the key differences between these two snake species: 

Scientific name	Copperhead (Agkistrodon contortrix)	Cottonmouth (Agkistrodon piscivorus)
Geographic location	Endemic to eastern North America	Endemic to southeast United States
Natural habitat	Forests and rocky hills with a multitude of leaf and log cover	Wetlands, streams, lakes and swamps
Appearance	24 – 36 inches (61 – 90 cm) in size Copper and reddish-brown body Pink belly scales Hourglass markings on the back	30 – 42 inches (76 – 106.7 cm) in size Brown or tan when juvenile, they get darker in color while maturing Cream colored belly with dark spots 10 to 17 black crossbands Often have green or yellow tail tips when young
Venom	Low potency with the lethal dose being around 100 mg (0.0035 oz) Maximum yield 85 mg (0.00299 oz)	Medium potency with the lethal dose being around 100 – 150 mg (0.0035-0.0053 oz) Maximum yield 237 mg (0.0083 oz)

Let’s look at these differences in more detail:

Geographic Location

Let’s compare the habitat ranges of these two snakes.

Copperheads

Copperheads can often be found in the east and central United States, ranging from Florida, Georgia, and Alabama to Massachusetts and Illinois – 28 states overall. In regards to their location, they come in five subspecies:

Northern Copperhead

• Throughout the United States
• Mexico

Southern Copperhead

• Massachusetts
• Nebraska
• Texas

Broad Banded Copperhead

• Kansas
• Oklahoma
• Texas

Trans-Pecos Copperhead

• Trans-Pecos
• Northeastern Mexico

Osage Copperhead

• Central United States – Missouri and Kansas

Cottonmouths

A Cottonmouth’s natural habitat ranges from Virginia to Missouri and from Florida to Texas. 

They come in three subspecies:

Florida Cottonmouth

• Florida

Western Cottonmouth

• Indiana 
• Illinois
• Alabama
• Oklahoma
• Texas

Eastern Cottonmouth

• Georgia
• South and North Carolina
• Virginia

Natural Habitat

The natural habitats of these two snakes are vastly different, as you’re about to see below:

Copperheads

Copperheads thrive in wooded and rocky terrain with lots of vegetation, and they don’t like open spaces without a cover under which they can hide. 

They have no problem living in artificial constructions like old mines and foundations of old and new buildings, and they can even be found in suburban neighborhoods. When brumating, copperheads prefer south and west-facing burrows such as old logs, hollow stumps, and caves.

Cottonmouths

Cottonmouths usually live in or around bodies of water but are not limited to aquatic terrain. 

Although we associate cottonmouths with lakes, streams, and marshes, you can often find them in brackish water, and there have even been instances where they have been spotted in saltwater. 

In the northern part of the United States, cottonmouths hibernate during the winter in burrows made by crayfish or tortoises and rotten, hollow logs. At the same time, in the south, brumation is often short or cut out altogether.

Size and Appearance

Let’s compare the appearance and size of these two species:

Copperheads

Copperheads are beautiful medium-sized heavy-bodied snakes that range in size from 7 inches (18 cm) when born to 36 inches (90 cm) when grown. 

They are sexually dimorphic regarding their size, meaning that the females grow to be much larger than males. The biggest copperhead ever recorded was 4 feet 5 inches (134 cm) long and was found in Tennessee.

They can be grey, copper colored, tan, or brown, with a head that varies from yellow to copper. Copperheads have keeled scales and bands in the form of an hourglass with marks between the bands. Young copperheads have green, and yellow tail ends that disappear by the age of 4. 

Here’s a great YouTube video with tips and tricks for identifying a baby copperhead:

Since they are pit vipers, they are recognizable by the temperature-sensitive pit located near their nose on the side of their eye, which helps them find their prey even when it’s completely dark.

Cottonmouths

Even though cottonmouths are also pit vipers like copperheads, they have vastly different coloring and differ in size. Cottonmouths are larger than copperheads and are usually between 30 and 42 inches (76 and 106.7 cm) in length. 

They have large and heavy bodies and triangular heads. Their scales are keeled, meaning they are not smooth but have a ridge in the middle that gives them a rough texture. They have crossbands all over their bodies, and their color can range from brown and olive ground colors to such a dark black that the crossbands become almost invisible. 

Their heads are very dark, with a recognizable white inner mouth they get their name from and a dark line through their eyes. Unlike copperheads, cottonmouth males are larger and heavier than females.

Here’s a video of a copperhead vs. cottonmouth fight from YouTube where it’s easy to see the difference in size and color:

Venom

The venom of both the copperhead and cottonmouth are potent and can be fatal. 

Copperheads

Although copperheads are usually not aggressive, and their bite is rarely fatal, the dose sufficient to kill a human is only 100 mg (0.0035 oz) of venom. If a bite does happen, antivenom is not a must – it will, however, help speed up the recovery process. 

Copperheads usually produce around 26 mg (0.0009 oz) of venom per bite, the largest recorded amount being 85 mg (0.002998 oz). Their venom is neurotoxic, coagulates the blood, and destroys muscle tissue. 

Copperheads cause an estimated 3000 bites per year, but in the last 120 years, only six people died due to their envenomation, and these were primarily because of allergic reactions, not the venom itself.

Cottonmouths

Cottonmouths’ venom is more potent and dangerous than that of copperheads. They are responsible for around 255 bites per year, but in the last 100 years, they have caused only two deaths. It’s important to remember that not every snake bite ends up in envenomation – only about 80% do.

Cottonmouth venom is, however, quite potent, with an average 125 mg (0.0044 oz) venom yield and a recorded maximum of 237 mg (0.0083 oz). Their venom wreaks havoc on the surrounding tissue causing tissue and muscle damage, internal bleeding, and inflammation. It induces ecchymosis, edema, and severe pain and has even been known to cause the loss of the envenomated limb.

Interesting Facts

Now that we’ve learned some basic information about copperheads and cottonmouths, let’s take a look at some fascinating facts:

Copperheads

• They are responsible for most snake bites in the U.S. per year. Copperheads are aggressive and won’t back down from a fight.
• They are the carrier of the eastern equine encephalitis virus.
• Most deaths related to copperhead bites are actually allergic reactions to copperhead antivenom.
• Same as cottonmouths, copperhead females can produce offspring without the help of males – this is done through the process named parthenogenesis.
• Copperheads produce a musk that smells of cucumbers when feeling threatened.
• Copperhead venom has been linked to the possible curing of cancer. It prevents abnormal cells from bonding with others and perhaps holds the key to a future without cancer.

Cottonmouths

• Young cottonmouths use their bright-colored tail for caudal luring. They wiggle their tail around, making frogs and lizards think it’s a juicy worm, making them careless and soon a meal themselves.
• They lose color while aging. First, they lose their brightly colored tails, and then they keep becoming more and more black. This also explains one of their many nicknames – the black snake.
• Cottonmouths have another nifty nickname – trap or snapping jaws. This is caused by a loud snapping movement, and sound cottonmouths make when bopped on the nose.
• Like copperheads, cottonmouths are ovoviviparous. This means they produce eggs but gestate them in their productive tract and give birth to live babies that actually hatch inside their mothers.
• Unlike copperheads, they are timid and will run away from conflict. They won’t attack a human unless they have no other option.
• Cottonmouths are fantastic swimmers. Unlike most snakes that just keep their head above the surface, cottonmouths float their whole body at water level.

Final Thoughts

Despite the many similarities between these snakes, they’re still two vastly different species. Cottonmouths and copperheads are both beautiful but also potentially dangerous, which is why it’s important to learn how to recognize them. 

With that said, although they seem scary and intimidating at first glance, they’re actually fascinating animals with interesting lives and aren’t a threat to humans unless we make them one ourselves. 

Some of them may even carry the solution to the scourge of our time – cancer.