Distinguishing between a venomous and nonvenomous snake can be challenging, yet it is important for safety. While many snakes are harmless, some possess venom that can pose significant health risks to humans. Understanding their differentiating characteristics is a valuable skill, though accurate identification can be complex due to natural variations and mimicry.
Prioritizing Safety
Encountering a snake can be startling, but the safest approach is always to maintain a considerable distance. Never attempt to handle, capture, or harm any snake, regardless of its perceived type. Most snake bites occur when people try to interact with them. Prioritizing personal safety and avoiding direct contact minimizes risk for both humans and wildlife.
Key Distinguishing Features
Identifying snakes often involves observing several visual characteristics, though these features are not universally definitive due to exceptions and variations among species.
Head Shape
Many venomous snakes, particularly pit vipers, commonly exhibit a triangular or spade-shaped head that appears broad at the back and tapers towards a narrower neck. However, some non-venomous snakes can flatten their heads when threatened, mimicking this triangular appearance as a defensive strategy. Conversely, certain venomous species, such as coral snakes, possess a more rounded or streamlined head shape, similar to many non-venomous snakes.
Pupil Shape
The shape of a snake’s pupils can offer another clue, though it is not always reliable. Most venomous snakes in North America, particularly pit vipers, typically have vertical, slit-like pupils, resembling a cat’s eye. In contrast, non-venomous snakes generally have round pupils. An important exception is the venomous coral snake, which has round pupils. This feature can be difficult to observe safely and accurately, as pupils can appear round in low light.
Scales
Observing a snake’s scales, particularly those on its underside, can provide helpful indicators. Venomous pit vipers often have a single row of scales running along the underside of their tail, from the anal plate to the tail tip. Non-venomous snakes, by comparison, typically display two rows of scales beneath their tail. Many venomous snakes have keeled scales, which possess a raised ridge down the center. However, keeled scales are also present in numerous non-venomous species, so this alone is not a reliable identifier.
Rattles
The presence of a rattle is a clear indicator of a rattlesnake, a type of venomous snake. The rattle consists of interlocking, hollow segments made of keratin at the end of the tail, which produce a distinctive buzzing or whirring sound when vibrated. While rattlesnakes often use this as a warning, not all will rattle before striking, and young rattlesnakes may have a small or undeveloped rattle. Furthermore, some non-venomous snakes can vibrate their tails in dry leaves or grass, creating a sound that might mimic a rattle.
Pits
Many venomous snakes, known as pit vipers, possess heat-sensing pits located between their eyes and nostrils. These small, deep depressions allow the snake to detect the infrared radiation emitted by warm-blooded prey, aiding in hunting. Non-venomous snakes do not have these pits. While this feature is a reliable sign of a pit viper, observing it requires getting close to the snake, which is not advisable.
Coloration and Patterns
Snake coloration and patterns are highly variable and can be misleading indicators of venomousness. Many venomous snakes display bright colors or distinct patterns, which can serve as a warning to predators. For example, some coral snakes have characteristic red, yellow, and black banding. However, numerous non-venomous snakes also exhibit vibrant colors or mimic the patterns of venomous species, making color alone an unreliable factor for identification.
Understanding Regional Variations and Mimics
Snake identification can be further complicated by geographic diversity and the phenomenon of mimicry. Features indicating a venomous snake in one region may not apply in another, highlighting the importance of understanding local snake populations.
Mimicry is a biological adaptation where a harmless species evolves to resemble a dangerous one, gaining protection from predators. A notable example is the resemblance between certain non-venomous kingsnakes and the venomous coral snakes. Kingsnakes, with their similar banding patterns, can deter predators that have learned to avoid the truly dangerous coral snake. This strategy makes visual identification challenging, so local knowledge and reliable regional guides are valuable resources.
What to Do If Unsure
If there is any uncertainty about whether a snake is venomous or non-venomous, it is safest to assume it is venomous and act with caution. If a snake bite occurs, it is important to call emergency services immediately.
Remove any jewelry or tight clothing from the bitten limb before swelling begins. Gently wash the bite area with soap and water, then cover it loosely with a clean, dry dressing. Keep the bitten limb as still as possible and, if practical, position it lower than the heart to potentially slow the spread of venom.
It is important to avoid actions that could worsen the situation. Do not attempt to capture or kill the snake for identification, as this increases the risk of further bites. Do not apply a tourniquet, cut the wound, try to suck out the venom, or apply ice. These methods are ineffective and can cause additional harm. Seeking professional medical attention promptly is the most effective course of action for any snake bite.