Cottonmouth vs Common Watersnake
Is that a water moccasin or a harmless watersnake?
The quick tell
Watch how it swims. A Cottonmouth rides high, buoyant as a pool noodle, with its head tilted up out of the water. A watersnake swims low, body at or below the surface. On land, a cornered Cottonmouth stands its ground and gapes a white mouth; a watersnake bolts for the water.
Field marks, side by side
| Cottonmouth | Common Watersnake | |
|---|---|---|
| Swimming | Floats high on the surface, head angled up | Swims low, mostly submerged |
| Face | Blocky head, dark band through the eye, pale lips | Rounder eye, no heavy facial band |
| Defense | Coils, stands ground, gapes cotton-white mouth | Flees instantly; bites only if grabbed |
| Build | Thick and heavy-bodied, dark and often patternless with age | Slimmer; banded when young, darkening with age |
Still not sure which one you found?
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Get Huck - freeCommon questions
Do Cottonmouths chase people?
No. It is a persistent myth. Cottonmouths stand their ground and bluff with the white gape, which people read as aggression. Given room, they leave. A snake swimming toward you is almost always just heading for the same bank you are standing on.
How far north do Cottonmouths live?
They are a Southeastern species - roughly Virginia to Florida, west to Texas and up the Mississippi lowlands to southern Illinois. A "water moccasin" sighting in New England, Michigan, or most of the Midwest is a Common Watersnake.