Vibrant colors in nature often serve as a warning. Some snakes display striking banded patterns of red, yellow, and black. However, not all brightly colored, banded snakes are dangerous, making accurate identification important for safety. Recognizing the specific arrangement of these color bands is key to distinguishing between venomous and harmless species.
The Coral Snake’s Warning Colors
North America is home to several venomous coral snake species, including the Eastern, Texas, and Arizona coral snakes. They all share a distinct color scheme: alternating bands of red, yellow, and black that completely encircle their bodies. On a true North American coral snake, the red bands directly touch the yellow bands. This arrangement is remembered by the mnemonic rhyme: “Red on yellow, kill a fellow.”
Other identifying features of these snakes include a rounded, black snout followed by a wide yellow band behind the eyes. Their heads are typically small and not distinctly wider than their necks. Smooth, shiny scales contribute to their polished appearance.
Common Mimic Snake Patterns
Several non-venomous snakes, such as the scarlet king snake and various milk snake subspecies, closely resemble the venomous coral snake. These harmless mimics display banded patterns of red, black, and yellow or white. A key difference lies in the order of their bands.
On mimic snakes, the red bands touch the black bands, rather than the yellow. This contrasting pattern is captured by a different mnemonic: “Red on black, friend of Jack.” Scarlet king snakes have a red snout, unlike the coral snake’s black one. Some milk snakes may also exhibit a light-colored V- or Y-shaped mark on the back of their heads.
The Reason for the Resemblance
The resemblance between venomous coral snakes and their harmless counterparts is a classic example of Batesian mimicry. This phenomenon occurs when a non-harmful species, the mimic, imitates the warning signals of a dangerous species, the model. Predators that avoid the dangerous model are then deterred by the mimic.
This evolutionary strategy provides a survival advantage for the mimic by deceiving predators who associate the bright colors with danger. Studies using artificial snake models have demonstrated that predators are significantly less likely to attack mimics where venomous coral snake models are present. This supports the effectiveness of this deceptive coloration.
Geographic Location as an Identification Clue
While identification rhymes are helpful, their applicability is limited to coral snakes found in the United States. These rules do not apply to coral snakes in other parts of the world, particularly Central and South America, where venomous species can display different color patterns.
In the U.S., Eastern coral snakes are typically found across the southeastern coastal plains, from North Carolina to Florida and westward into Louisiana. The Texas coral snake inhabits western Louisiana, eastern Texas, and parts of Arkansas. The Arizona coral snake is located in central and southern Arizona, and extreme southwestern New Mexico. Knowing which species are native to a region aids identification.