The most common example of Batesian mimicry in North America involves the highly venomous Coral Snake and non-venomous species that imitate its bright, contrasting color pattern of red, black, and yellow rings. This strong resemblance often leads to confusion for people encountering these snakes in the wild, where misidentification could have severe consequences. The confusion centers on a few different species, but one non-venomous snake is the primary mimic across the southeastern United States.
The Scarlet Kingsnake: Master of Mimicry
The snake that most commonly resembles the Coral Snake is the Scarlet Kingsnake (Lampropeltis elapsoides). This non-venomous reptile is a subspecies of Kingsnake found throughout the southeastern and eastern United States, often in habitats like pine flatwoods, savannas, and cultivated fields. The Scarlet Kingsnake possesses a striking tricolored banding pattern of red, black, and yellow or white rings, making it a convincing imitation. Kingsnakes are largely harmless to humans and are, in fact, beneficial to the ecosystem because their diet includes rodents and other snakes, even venomous ones. Its mimicry is effective because predators that avoid the venomous Coral Snake will also avoid the harmless Kingsnake.
The Critical Identification Rhyme
To distinguish the harmless Scarlet Kingsnake from its venomous counterpart, a mnemonic rhyme has been used for generations in the United States: “Red touches black, friend of Jack; Red touches yellow, kills a fellow.” This directly addresses the arrangement of the colored bands. In the non-venomous Kingsnake, the red bands always border the black bands. Conversely, the venomous Coral Snake’s pattern features the red bands directly touching the yellow bands.
This rhyme is reliable for the two native species of Coral Snakes found in the United States. However, this simple rule can be misleading when applied to similar-looking snakes found outside of the U.S., particularly in Central and South America. A more reliable secondary feature is the snake’s head color; the venomous Coral Snake typically has a black snout followed by a yellow band, while the Kingsnake’s snout is often reddish.
Understanding the True Threat
The true danger lies with the Coral Snake, a member of the Elapidae family, which also includes cobras. The venom is primarily neurotoxic, meaning it attacks the nervous system and can cause paralysis, including the muscles necessary for breathing. Unlike pit vipers, which have large, retractable fangs, the Coral Snake possesses small, fixed fangs at the front of its mouth.
While it was once believed that Coral Snakes needed to chew to deliver their venom effectively, they can quickly inject venom in a brief bite. The bite often causes little to no immediate pain or swelling, which can lead to a dangerous delay in seeking treatment. Symptoms like muscle weakness, slurred speech, and difficulty swallowing can be delayed for several hours, but once they begin, they can progress rapidly to respiratory failure.
What to Do in an Encounter
The safest course of action when encountering any snake with red, black, and yellow banding is to assume it is venomous and leave it undisturbed. Never attempt to handle, capture, or kill the snake, as most bites occur when a person tries to interact with the animal. Simply observe the snake from a safe distance and allow it to move away.
If a bite from a Coral Snake is suspected, immediate emergency medical attention is mandatory. Immobilize the affected limb and keep it at or below the level of the heart to slow the spread of venom. Do not use ice, a tourniquet, or suction devices, as these interventions are harmful and ineffective. Definitive treatment involves the administration of antivenom in a hospital setting, and continuous monitoring is required for 24 to 48 hours due to the potential for delayed, life-threatening symptoms.