Oklahoma is home to over 40 snake species, but only seven are venomous, all belonging to the Pit Viper family, Crotalidae. While often called “poisonous,” these snakes are technically venomous, meaning they inject toxins through a bite. Knowing how to identify these few species and understanding their shared characteristics is the best way to avoid a dangerous encounter.
Identifying Oklahoma’s Venomous Species
The Copperhead is one of Oklahoma’s most widespread venomous snakes, represented by two species: the Eastern Copperhead and the Broad-banded Copperhead. Their distinct pattern consists of alternating light and dark bands that narrow dramatically across the back, creating a characteristic hourglass or saddle shape. The base color ranges from tan to pinkish, overlaid with reddish-brown or copper-colored markings. Copperheads inhabit diverse environments, including rocky outcrops, grasslands, and suburban areas.
The Cottonmouth, or Water Moccasin (Agkistrodon piscivorus), is a semi-aquatic species found near permanent water sources, such as swamps, lakes, and streams in the eastern and southern parts of the state. Adults are heavy-bodied and typically display a dark coloration of olive, brown, or black, often obscuring their cross-banded pattern. When threatened, the Cottonmouth exposes the bright, cotton-white interior of its mouth, which gives the snake its common name.
Rattlesnakes represent the largest group of venomous snakes in Oklahoma, with five species present, including the Western Diamondback (Crotalus atrox) and the Timber Rattlesnake (Crotalus horridus). The Western Diamondback is the largest venomous species in the state, recognizable by the dark, diamond-shaped blotches along its back and the bold black and white bands encircling its tail just above the rattle. The Timber Rattlesnake, also called the Canebrake Rattlesnake, has a lighter base color with dark, jagged V-shaped crossbands and is often found in forested areas and rocky terrain.
The smaller rattlesnake species include the Prairie Rattlesnake (Crotalus viridis), the Western Massasauga (Sistrurus tergeminus), and the Western Pygmy Rattlesnake (Sistrurus miliarius). Prairie Rattlesnakes are typically found in the western regions and panhandle, preferring grasslands and prairies. The Massasauga and Pygmy Rattlesnakes are smaller in size and possess a tiny rattle that often produces a sound described as a faint buzz, making them harder to detect than their larger cousins.
General Characteristics of Pit Vipers
Pit Vipers share several distinct physical features that distinguish them from non-venomous species. The head is noticeably wide and triangular, contrasting sharply with the narrower neck due to the large venom glands.
Sensory Organs
Pit Vipers are equipped with a pair of specialized heat-sensing organs, called loreal pits, positioned between the eye and the nostril. These pits allow the snake to detect infrared radiation, helping them locate warm-blooded prey even in darkness. They also possess vertically elliptical pupils, resembling a cat’s eye, which helps regulate light intake during their mostly nocturnal activity.
Tail Scales
A reliable identification feature is found on the underside of the tail. Non-venomous snakes typically have two rows of scales running from the vent to the tail tip, while Pit Vipers have a single, undivided row of scales in this post-ventral region.
Emergency Response and Prevention
Simple precautions are the most effective way to prevent a snake bite, as these animals generally only strike when they feel threatened. When walking through tall grass, rocky areas, or wooded terrain, wearing sturdy, high-top boots and long pants offers protection. Always watch where you place your hands and feet, especially when stepping over logs or reaching into crevices, as snakes often hide there. Never attempt to handle or harass any snake.
If a bite occurs, immediately call 911 or local emergency services. Getting the victim to a medical facility quickly is essential, as antivenom is the only definitive treatment. While waiting for help, the victim should remain calm and still to slow the spread of venom.
Remove constricting items, such as rings, watches, or tight clothing, from the bitten limb immediately, as severe swelling will likely occur. The wound area should be gently cleaned with soap and water and covered with a clean, dry dressing. Keep the bite site at or slightly below the level of the heart to minimize the flow of venom toward the core of the body.
It is important to know what actions to avoid, as many traditional first aid methods can cause harm. Do not apply a tourniquet, cut the wound, or attempt to suck out the venom, as these actions are ineffective and can cause tissue damage or delay proper medical care. Also, do not use ice or apply any cooling agents to the bite, as this has no proven benefit and may worsen tissue injury.