The coral snake, a highly venomous reptile found in North America, possesses a distinctive pattern of colored bands that serves as a warning signal. This appearance is closely mimicked by several non-venomous species, creating an identification challenge. Because confusing the dangerous snake with its harmless look-alikes could have severe consequences, people developed a simple, rhyming mnemonic device to quickly differentiate the species based on its coloration.
The Mnemonic Rhyme for Identification
The old saying about the coral snake is a mnemonic rhyme intended to clarify which banded snake is venomous. The most common variation is: “Red touch yellow, kill a fellow; red touch black, friend of Jack.” This rhyme focuses on the order in which the colored bands meet along the snake’s body.
The first part, “red touch yellow, kill a fellow,” describes the pattern of the venomous Eastern Coral Snake (\(Micrurus\) \(fulvius\)). In this species, the red bands are bordered directly by the yellow bands. The second part, “red touch black, friend of Jack,” describes the pattern of the non-venomous mimics. This difference in the sequence of colors is the most important detail the rhyme conveys. Coral snakes, relatives of the cobra, deliver a potent neurotoxin through short, fixed fangs, making accurate identification important for safety.
Understanding the Mimics
The identification rhyme is necessary because non-venomous snakes have evolved to closely resemble the coral snake. This biological phenomenon is known as Batesian mimicry, where a harmless species copies the warning coloration of a harmful species to deter predators. Predators that avoid the venomous coral snake will also avoid the mimic, mistaking it for the dangerous model.
The most common mimic in the southeastern United States is the Scarlet Kingsnake (\(Lampropeltis\) \(elapsoides\)), which shares the red, yellow, and black bands. The kingsnake’s pattern follows the “red touch black” rule, meaning its red bands are separated from the yellow bands by black bands. Other non-venomous species, like the Scarlet Snake, also exhibit this pattern, benefiting from the coral snake’s aposematic coloration. The slight difference in band sequence is usually enough to distinguish the two.
Geographic Variations and Safety
While the rhyme provides a useful guideline, its reliability is primarily limited to the Eastern Coral Snake and the Texas Coral Snake in the southeastern United States. The rule is not universally applicable, and relying on it alone can be hazardous, particularly for the Arizona Coral Snake (\(Micruroides\) \(euryxanthus\)). Furthermore, some non-venomous snakes, like the Sonoran Shovel-nosed Snake, occasionally have patterns where red bands touch yellow bands, contradicting the rhyme.
Aberrant individuals, which are rare variations that do not adhere to the expected pattern, also pose a risk in regions like Florida. Outside of North America, where many other coral snake species and mimics exist, the rhyme is entirely unreliable. Therefore, the most prudent course of action is to never handle any snake with this characteristic red, yellow, and black banding pattern.
If a bite occurs, immediate medical attention is required because the coral snake’s neurotoxic venom affects the nervous system and can cause respiratory paralysis. Though bites are uncommon due to the snake’s reclusive nature, caution is necessary when encountering any banded snake in the wild. Leaving all snakes undisturbed is the safest approach to prevent conflict.