Many people encounter snakes near water and wonder if they are dangerous. While most snakes found in aquatic environments are harmless, some venomous species can look similar, leading to confusion and unnecessary fear. Understanding the differences between these snakes is important for both human safety and the conservation of these animals.
Understanding “Water Snakes”
The term “water snake” typically refers to several non-venomous species commonly found in and around freshwater habitats. In North America, species from the genus Nerodia, such as the northern water snake (Nerodia sipedon), brown water snake (Nerodia taxispilota), and plain-bellied water snake (Nerodia erythrogaster), are frequently encountered. These snakes inhabit lakes, rivers, ponds, and swamps, spending a significant portion of their lives in or very near water.
Water snakes are generally heavy-bodied with rough, keeled scales, and can grow to lengths of 3 to 4.5 feet, with some individuals reaching up to 5 feet. Their coloration varies but often includes shades of brown, gray, or olive with patterns of blotches or bands that may darken with age. These snakes play a role in their ecosystems by feeding on fish and amphibians.
Key Differences: Harmless vs. Venomous Look-Alikes
Distinguishing harmless water snakes from venomous look-alikes, primarily the cottonmouth (Agkistrodon piscivorus), is important. Cottonmouths are pit vipers. While both are found near water, several characteristics can help tell them apart from a safe distance.
One key difference is head shape. Cottonmouths have a distinctly triangular, blocky head due to their venom glands, noticeably wider than their neck. Harmless water snakes generally have a more rounded head that blends smoothly into their body, though they can flatten their heads to appear more triangular when threatened. Pupil shape is another distinguishing feature: cottonmouths have vertical, cat-like pupils, while water snakes have round pupils. Cottonmouths also possess heat-sensing pits between their eyes and nostrils, a feature absent in water snakes.
Their behavior in water also differs: cottonmouths often swim with their entire body floating on the surface, while water snakes typically swim with only their head visible above the water. Coloration can be variable in both, but cottonmouths often have a dark band or “mask” through the eye and may display broad crossbands that can darken with age. When threatened, a cottonmouth may open its mouth wide to reveal the stark white interior, while water snakes may flatten their bodies, musk, or strike repeatedly.
Encountering a Water Snake: Best Practices
When encountering any snake near water, maintaining a safe distance is important. Snakes are defensive and prefer to avoid confrontation. Never attempt to approach, handle, or provoke a snake.
Allow the snake ample space to retreat; do not block its escape route. Keeping pets on a leash and children close by can prevent accidental encounters. Water snakes play a role in the ecosystem, controlling pest populations. Even non-venomous water snakes can bite if they feel threatened.
If a Bite Occurs
If a snake bite occurs, seek immediate medical attention, especially if the bitten area shows swelling or pain. Do not attempt to capture or kill the snake for identification, as this increases the risk of further bites.
For suspected non-venomous bites, clean the wound thoroughly with soap and water, apply an antiseptic, and cover it with a clean bandage. Monitor the wound for any signs of infection. For suspected venomous bites, remain calm and keep the bitten area below the level of the heart. Remove any tight clothing or jewelry from the affected limb and call emergency services immediately. Do not apply a tourniquet, cut the wound, attempt to suck out venom, or apply ice, as these actions can cause more harm.