Copperheads and water moccasins are two venomous snake species frequently encountered in the United States. Distinguishing between them is important for safety. While they share some characteristics, they are distinct species with different appearances, behaviors, and preferred habitats. This article will clarify the differences between copperheads and water moccasins, also known as cottonmouths.
Not the Same Snake
Copperheads and water moccasins are not the same snake species. They both belong to the Agkistrodon genus, placing them within the pit viper family (Viperidae). The copperhead is scientifically known as Agkistrodon contortrix, while the water moccasin is Agkistrodon piscivorus. Their shared genus means they possess similar features, such as heat-sensing pits located between their eyes and nostrils, which help them detect warm-blooded prey. Their geographic ranges broadly overlap across the southeastern United States, from Texas to Florida and as far north as Nebraska for copperheads and Virginia for water moccasins.
Visual Identification
Identifying copperheads and water moccasins relies on their unique physical characteristics. Copperheads typically have a base coloration ranging from light tan to reddish-brown or coppery hues, with distinctive dark brown or chestnut-brown hourglass-shaped crossbands. Their heads are often a coppery color, which gives them their common name, and are somewhat triangular but less pronounced than those of water moccasins. Juvenile copperheads have a bright yellow or greenish-yellow tail tip, which fades as they mature.
Water moccasins are generally darker and heavier-bodied snakes, ranging from olive to dark brown or almost black. While juveniles may display more distinct reddish-brown bands, adult water moccasins often have patterns that are less visible or appear almost solid dark. A key distinguishing feature is the characteristic white, “cotton-like” interior of their mouth, which they display as a defensive warning when threatened. Water moccasins possess a blockier, more triangular head with prominent jowls, and a dark stripe often runs from their eye to the angle of their jaw. Both species, as pit vipers, have vertical, cat-like pupils.
Habitat, Behavior, and Diet
Copperheads generally prefer drier, upland habitats such as wooded areas, rocky outcrops, and even suburban environments, though they can be found near water sources. They are often reclusive and rely on their camouflage, frequently freezing in place when approached rather than fleeing. This tendency to remain still can lead to accidental encounters, as their patterned skin blends seamlessly with leaf litter. Copperheads primarily prey on small mammals like mice and shrews, as well as large insects such as cicadas and caterpillars.
Water moccasins, conversely, are semi-aquatic snakes strongly associated with various freshwater environments, including lakes, rivers, swamps, marshes, and ditches. They are the only venomous snake in the U.S. that spends a significant amount of time in water. When swimming, water moccasins often keep their entire body afloat on the surface, while non-venomous water snakes typically swim with only their head visible. Their defensive behavior often involves coiling their body and opening their mouth wide to reveal the white lining. Water moccasins primarily feed on fish, frogs, and other small aquatic animals.
Venom and Safety
Both copperheads and water moccasins are venomous pit vipers, meaning their venom contains a complex mixture of toxins primarily affecting blood and tissue. This hemotoxic venom can cause pain, swelling, and tissue damage at the bite site. While bites from both species are painful and require immediate medical attention, they are rarely fatal to healthy adults. The severity of a bite depends on factors such as the amount of venom injected, the bite location, and the individual’s overall health.
Most snakebites occur when people accidentally step on or attempt to handle a snake. Copperheads are responsible for a significant number of snakebites in the U.S. due to their tendency to freeze when threatened and their presence in populated areas. Water moccasins are generally not aggressive and typically bite only if provoked or handled. To promote safety, observe snakes from a distance, avoid touching or handling them even if they appear dead, and be aware of surroundings in known snake habitats. If a bite occurs, stay calm, remove any jewelry or constricting items from the affected area, keep the bitten limb still, and seek immediate medical help.