Distinguishing between venomous and nonvenomous snakes is an important skill for personal safety and for the conservation of these often misunderstood reptiles. While many snakes are harmless and play a beneficial role in ecosystems, some possess venom that can be dangerous to humans. Knowing key characteristics can help individuals make informed decisions when encountering these creatures in the wild.
Key Visual Indicators
The shape of a snake’s head often provides a clue. Many venomous snakes, particularly pit vipers like rattlesnakes, copperheads, and cottonmouths, typically have a triangular or spade-shaped head distinct from their narrower neck. This shape is due to venom glands in the rear of the jaw. However, some non-venomous snakes mimic this by flattening their heads when threatened, making this indicator less reliable.
The shape of a snake’s pupils is another visual cue. Many venomous snakes, especially pit vipers, often have vertical, elliptical pupils resembling a cat’s eye. Non-venomous snakes typically possess round pupils. This rule has exceptions; venomous coral snakes have round pupils. Pupil shape can also change with light conditions, appearing round in low light.
A distinct feature of pit vipers is heat-sensing pits, or loreal pits. These small indentations are on each side of the snake’s head, between the eye and nostril. They allow pit vipers to detect infrared radiation, helping them “see” warm-bodied prey. While a definitive sign, they are difficult to observe safely.
Coloration and Pattern Clues
Coloration and patterns offer identification clues, though not always foolproof due to mimicry. Some harmless snakes display colors and patterns similar to venomous species. Therefore, relying solely on color can be misleading.
A widely known rhyme helps distinguish the venomous coral snake from its non-venomous mimics, like the scarlet kingsnake, in the U.S. The rhyme states, “Red touches yellow, kill a fellow; red touches black, venom lack.” This refers to the banding pattern where, in coral snakes, red bands touch yellow bands, while in mimics, red bands touch black bands. This rhyme is primarily reliable for U.S. native coral snakes and does not apply universally.
Behavioral Cues and Habitat
A snake’s behavior can provide context for identification, though these cues are less definitive than physical traits. Many venomous snakes exhibit defensive behaviors when threatened, such as coiling, hissing, or striking. Rattlesnakes, for example, vibrate their tail to produce a distinct rattling sound as a warning. Some non-venomous snakes also mimic these behaviors, like tail buzzing or head flattening.
Habitat preferences also offer guidance. Cottonmouths, or water moccasins, are venomous snakes found in or near water bodies like swamps and slow-moving streams. They often float on the surface with most of their body exposed. Non-venomous water snakes tend to swim with more of their body submerged, often only showing their head. However, some non-venomous species can also float, making this a general trend.
Important Caveats and When to Seek Expert Help
The identification guidelines are general rules with exceptions. Not all venomous snakes fit typical descriptions. Relying on a single characteristic can lead to misidentification and dangerous situations.
The safest approach when encountering any snake is to maintain a respectful distance and avoid interaction. If you are unsure whether a snake is venomous, it is always best to assume it is and leave it alone. Attempting to approach, handle, or harm a snake significantly increases the risk of a bite, as most snake bites occur when people try to interfere with the animal.
If a snake is in an area of concern, such as inside a home or in a frequently used space, consider taking a clear photograph from a safe distance for later identification. Then, contact local wildlife authorities, animal control, or professional snake removal services. These professionals have the expertise and equipment to safely identify and relocate snakes, minimizing risk to both humans and the animal. If a snake bite does occur, seek immediate medical attention regardless of whether the snake is thought to be venomous.