Yes, snakes can bite underwater. Most snakes you encounter in the water are harmless, though. In North America, the ones you need to look out for are rattlesnakes, copperheads, cottonmouths/water moccasins, and coral snakes. These snakes are venomous and a bite could be deadly.
Which Snakes Should I Worry About?
Though a vast majority of snake species live on land, snakes are strong swimmers — even rattlesnakes. And though most species of snake in the U.S. are considered harmless, even a non-venomous snake can bite when threatened.
Most snake bites happen because a person has accidentally disturbed the snake, for example by sitting on it. Most snakes will retreat when people are near, but cornered snakes or snakes that are being handled will bite to defend themselves. Here are four venomous snakes you might find in the water:
Cottonmouths. Cottonmouths, also called water moccasins, live close to water and can often be found in the water. Cottonmouths are often found in the Southeastern and Southwestern U.S. near irrigation ditches, swamps, and other wet areas.
Coral snakes. Coral snakes also live near water. There are several species of aquatic coral snakes that have flatter bodies and paddle-like tails that allow them to move through the water at incredible speeds.
Despite being venomous, coral snakes are not aggressive and will avoid humans. Coral snakes spend most of their time under rocks or rotting logs and play an important role as predators in food chains.
There has only been one reported death following a coral snake bite in the U.S. since the 1960s, and that person failed to seek medical attention.
Copperheads. Copperheads can be found near swamps, ponds, and streams from Florida to Massachusetts and even Nebraska. Of the four snakes listed here, copperheads have the mildest venom, and bites are almost never fatal.
Rattlesnakes. Rattlesnakes are easy to identify because of the rattling sound they make when threatened. There are over 25 species of rattlesnake in the U.S., and despite their bad rap, rattlesnakes are also not aggressive toward humans.
They will make their rattling sound to warn off threats and prefer to retreat when humans are close by. But rattlesnake bites can be serious and a cornered snake will bite.
How to Tell the Venomous snakes from the Non-venomous Ones
Because most species of snake you’re likely to encounter will not be venomous, being able to tell the venomous ones from the harmless ones can help you avoid unnecessary worry.
Here’s how to identify the venomous ones:
Cottonmouths. Cottonmouths can look very similar to harmless water snakes, but you can tell them apart by their physical characteristics. Cottonmouths are pit vipers and have a distinctive “pit” on their heads between their eyes and nose that is sensitive to heat.
Their heads are also flat on top, rather than rounded like you would see on harmless water snakes. When threatened, they tend to turn their heads up, opening their mouths and showcasing their white interiors, which resembles cotton.
Northern water snakes, banded water snakes, and brown water snakes are often mistaken for cottonmouths because their banding can resemble that of young cottonmouths.
Coral snakes. Coral snakes have distinctive, colorful banding and their very own rhyme — “Red against black is a friend, Jack. Red against yellow can kill a fellow.”
It’s important to pay attention to the order of the colors in a snake’s banding. Coral snakes always have banding that goes from yellow to black, back to yellow, then red. Coral snakes are the only snake on this list that aren’t pit vipers.
It’s important to note that this rhyme only applies to species in North America — Central and South America are home to snakes for whom this rhyme does not apply.
Copperheads. Copperheads are also pit vipers, and their heads can vary in color from yellow to copper. Young copperheads have a yellow tail tip.
Copperheads have hourglass-shaped bands and can sometimes have spots in between bands. You can also normally see two dots on the top of the head. Garter snakes, which are harmless, also sometimes have two dots on the top of their heads.
Rattlesnakes. Rattlesnakes can be identified by the rattles on their tails. While other snake species might make a rattling noise, only rattlesnakes have the rattles, which are made of keratin. Every time rattlesnakes shed their skin, a new rattle is added.
Rattlesnakes are also pit vipers and their heads are flat at the top rather than rounded like most harmless snakes.
While it’s important to steer clear of venomous snakes, even non-venomous snakes will bite if threatened. And snake bites can be nasty, often drawing blood and requiring medical attention. Whether the snake you’ve encountered is venomous or not, it’s best to leave it alone.
What to Do If You Encounter a Snake Underwater?
Don’t panic. Most water snakes are not venomous and even the venomous ones are not aggressive toward humans. Panicking might cause a commotion in the water, making the snake feel threatened rather than scaring it away. Threatening a snake could provoke a bite.
Stop and look. Give the water snake the opportunity to swim in the opposite direction or slip into a hiding spot — it’s likely they felt you coming and will retreat. Once you know which direction the snake is moving in, you can go the opposite direction. Don’t bother yelling to try to scare the snake away, they can’t hear you.
Keep you hands to yourself. Many snakes are great at camouflaging — they may appear to be dead wood on the surface of the water at first glance. Or they may be hiding under rocks or logs near the water’s edge.
Don’t reach out and grab anything until you’ve taken a good look, and never reach under rocks or logs with your bare hands — you might disturb a snake and provoke a bite.
Wear protective gear. Consider wearing water shoes to protect your feet, and depending on where you’re swimming, you might consider a wet suit which offers all over protection. Out of the water, wear boots that go past your ankle — most snake bites happen around the ankle area. Also consider wearing pants rather than shorts, which offer little protection to your legs.
Most snakes in the U.S. are harmless and snakes are an important part of the food chain, eating small mammals, insects and other reptiles. Seeing a snake in the water is no cause for immediate concern, since most will be harmless, but just in case, it’s best to leave any snakes you see alone.
Don’t attempt to handle them and certainly don’t try to kill a snake because you suspect it’s venomous. Most snakes are not aggressive toward humans and will avoid you if you avoid them.
Even bites from non-venomous snakes can be nasty. If you get bitten, regardless of whether you think the snake was venomous, you should seek medical attention.