Cottonmouth vs. Water Snakes: The Main Differences

Key Points

• Both snakes have adapted to living in water and also bear a close resemblance to each other.
• However being able to tell them apart is crucial since cottonmouths are extremely dangerous while water snakes are harmless.
• The main difference lies in the shape of the head in the water moccasin vs water snake, which is large and square for the former, and flat and round for the latter.

Cottonmouth snakes, also known as water moccasins, are incredibly venomous. Their venom can kill a human, so it’s understandable that so many people fear them—and frequently confuse harmless water snakes for the cottonmouth. However, it’s important to know the difference between the water moccasin vs water snake for your own safety, as well as the safety of harmless water snakes—who are often killed due to being confused with venomous cottonmouths! Let’s dive into what separates cottonmouth vs. water snakes!

Comparing Water Snake vs Cottonmouth

Water snakes, especially the northern water snake, can look very similar to cottonmouths. They are both dark in color, with darker markings along their bodies.

Water snakes may be banded like cottonmouths, or have patches that look similar to bands when observing them. Both water moccasin vs water snakes tend to stay close to fresh water sources and are found throughout the United States.

However, Cottonmouths do have some distinctive features which include a larger body and head, distinctive eyes, and pits on the sides of their faces.

Water snakes and cottonmouths look quite similar, possibly because they’ve both adapted to survive in the water. However, they are completely different snakes—even belonging to different families.

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In addition, it’s important to note that there are several species of water snakes, each slightly different in color and appearance.

These include:

• Northern Water Snake: This is the most common water snake found in the United States. At five feet in size, they are the most likely to be confused with Cottonmouths. They have dark splotches on their scales, which are easily mistaken for the dark bands of a Cottonmouth. If you cannot tell the difference, it’s always best to keep your distance from these snakes rather than risk yourself by getting closer.

• Southern Water Snake: Also known as banded water snakes, these snakes are found in the southern United States. They can be red, brown, or black in color, and are banded. Their coloration darkens as they grow older.
• Brown Water Snake: These snakes have light brown scales with darker patches. Their head is diamond-shaped. Brown water snakes are found in the Southeast of the United States and are often seen in trees, as well as in the water.
• Yellow-Bellied Water Snake: Just like the name suggests, these snakes have yellow undersides. The tops of their bodies are grey, green, or black. They live around the Gulf Coast.
• Red-Bellied Water Snake: These snakes are brown or grey with bright orange to red undersides. They are found on land more often than other water snake species.

The 5 key Differences Between Cottonmouths and Water Snakes

1.     Cottonmouths have Large, Boxy Heads

Cottonmouth heads and necks are distinct from their bodies. While Cottonmouths have square heads, water snakes have rounded or flat heads that are not thicker than their bodies.

In addition, cottonmouths always have an eye stripe. Water snakes often have this feature as well, but not always.

2.     Water Snakes are Thin with no Defined Neck

Water snake bodies are long and slender. Their head is not distinct from their body, so they have no defined neck.

Cottonmouths, on the other hand, are much thicker and heavier snakes. They also have big, blocky heads that stand apart from their bodies, creating a distinctive neck.

3.     Cottonmouths have Oval Pupils

Cottonmouths have oval, slit-like pupils—similar to that of a cat. Water snakes have circular pupils.

It is also worth noting that the eyes of cottonmouth snakes cannot be seen when observing them from above.

Those of water snakes on the other hand are visible when you look down at their heads.

4.     Water Snakes do not Have Pits

Cottonmouth snakes have pits on each side of their head, between their eyes and nostrils. These pits sense heat, allowing the snakes to detect and strike down prey.

Water snakes do not have these pits.

However, by the time you see if a snake has pits or not, you’re often too close for comfort! So, this isn’t a super reliable way for the common person to distinguish between these snakes.

5.     Cottonmouths Live Longer

Lastly, let’s consider the longevity of a water moccasin vs water snake. Cottonmouths can live about twice as long as water snakes in captivity. Some cottonmouths have lived over 20 years, though their lifespan in the wild is much shorter.

Captive water snakes only live up to 9-10 years. Though we don’t know their average wild lifespan, we can guess that it’s similarly short. Animals rarely live longer lives in the wild than they do in captivity.

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