Cottonmouth Snake Vs. Water Snakes: How To Tell The Deadly From The Harmless

You are wading in a Southern lake or flipping a kayak when a thick, dark snake swims toward you with its head held high.

One flick of its tail and your brain screams “COTTONMOUTH!”, but most of the time, it is actually a harmless water snake that just got mistaken for Florida’s most feared serpent.

This article is set to provide you with foolproof identification tricks that work even when your heart’s pounding. Let’s gooo!

 

Cottonmouth Snake Vs. Water Snakes: What is the Reason for the Confusion?

Both cottonmouths (Agkistrodon piscivorus) and non-venomous water snakes (genus Nerodia) share the same habitat, hunt the same prey, and get aggressively defensive when cornered.

 

Cottonmouth Snake Vs. Water Snakes: What Do They Look Like?

 

Feature	Cottonmouth (Venomous)	Water Snake (Harmless)
Head shape	Distinct triangular arrowhead	Narrow and blends into the body
Eyes	Vertical pupils (cat-eye) and heat-sensing pits	Round pupils
Body thickness	Very thick and almost chunky	Slender to moderate
Swimming style	Swims with its floating high (like a log)	Swims mostly submerged, with only its head above
Tail tip	Thick and does not taper much	Noticeably tapers to a point
Color pattern	Wide dark bands or solid dark (adults)	Narrow bands, often checkerboard
Mouth interior (if seen)	White	Pink or yellowish
Behavior when threatened	Opens its mouth wide and shows white, and coils	It flattens its head, vibrates its tail, and may bite, but it is non-venomous

 

Read also: Snake In The House: What To Do In These Situations

 

Cottonmouth Snake vs. Water Snakes: How to Differentiate them with the 30-Second Field Test

1. Look at Swimming Posture: If the entire body is floating high like a stick, then there is a high chance it is a cottonmouth, but if only the head is above water, then it is a water snake.
2. Check Head Shape from Side: If it has an arrowhead with an obvious neck, it is a cottonmouth. If it has no neck and its head is the same width as its body, it is a water snake.
3. Observe the Tail: If the tail is blunt and thick, it is a cottonmouth, and if it is thin and whiplike, it is a water snake.

If all three point to a water snake, relax, but if two or more scream “cottonmouth,” then you’d better back away slowly.

 

Cottonmouth Snake vs. Water Snakes: What are the Common Species?

Cottonmouth (Water Moccasin)

• It is the only venomous semi-aquatic snake in the southeast
• Adults grow 2 to 6 feet and are very thick-bodied
• The juveniles have a bright yellow tail tip (lure for prey)
• They can be found from Virginia to Texas, north to Illinois

 

What are some Common Water Snake Impostors?

• Northern Water Snake (Nerodia sipedon)
• Plain-Bellied Water Snake (Nerodia erythrogaster)
• Diamondback Water Snake (Nerodia rhombifer)
• Brown Water Snake (Nerodia taxispilota)

 

Cottonmouth Snake vs. Water Snakes: Do they Chase?

Do cottonmouths chase people? No, they do not. They may stand their ground and display, but will flee if given an escape route.

Water snakes, however, will chase you, as they are just trying to escape and are terrible at directions.

 

Cottonmouth Snake vs. Water Snakes: Do they Bite?

• Cottonmouth bites: There are usually 1,200 cottonmouth bites annually (mostly the fishermen handling them), but fatalities are very minimal, too, as the antivenom is very reliable.
• Water snake bites: There are thousands of water snake bite cases, as these snakes are super defensive. Water snakes hurt like hell but pose zero long-term threat.

 

Cottonmouth Snake vs. Water Snakes: What to Do If You Cannot Tell the Difference

1. Back away slowly
2. Never attempt to kill or handle
3. Take a photo for identification, but from a safe distance
4. Contact local wildlife authorities for removal

 

How to Prevent Being Bitten by a Cottonmouth Snake

• Wear water shoes in murky water
• Never put your hands where you cannot see (under logs, in holes)
• Use a walking stick to probe ahead
• Keep a flashlight handy at night, as cottonmouths are nocturnal hunters

 

Read also: Can Snakes Bite Underwater? Your Guide To Aquatic Snake Encounters

 

Conclusion

Scenario	Likely Identification
A thick snake swimming like a log	Cottonmouth
A thin snake with only its head above water	Water snake
A Snake opens its mouth, showing white	Cottonmouth
A snake that vibrates its tail in leaves	Could be either (both do it!)
You are north of Virginia or Texas line	Almost certainly a water snake

Master the swimming posture test, and you will correctly identify these gruesome encounters before your adrenaline even spikes. Thank you for reading!

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