Head to head
Kingsnake vs Coral Snake
Some kingsnakes and milk snakes wear almost exactly the rings of a venomous coral snake, a case of a harmless species borrowing a dangerous one's warning colours. Telling them apart matters, and there is a rule that works, but only in one region.
| Kingsnake | Coral Snake | |
|---|---|---|
| Venomous | No; kills by constriction | Yes; potent neurotoxic venom |
| Family | Colubridae (Lampropeltis) | Elapidae (Micrurus, Micruroides) |
| Role of the colours | Batesian mimicry, borrowed warning | Genuine warning (aposematism) |
| Band order (SE USA) | Red touches black; red snout | Red touches yellow; black snout |
| Head and body | Rounder head, often slightly larger | Small blunt head barely wider than neck |
| Diet | Snakes, rodents, lizards, eggs | Mostly other snakes and lizards |
| The rhyme works | Only in the southeastern United States | Only in the southeastern United States |
| Behaviour if found | May musk and bite; harmless | Usually flees; bite is a medical emergency |
Kingsnake vs Coral Snake: common questions
How do I tell a scarlet kingsnake from a coral snake?
In the southeastern United States, look at which colours touch and at the snout. On the venomous eastern coral snake, the red and yellow rings are adjacent, with no black between them, and the tip of the snout is black. On the harmless scarlet kingsnake and scarlet snake, the red rings are bordered by black, the yellow is separated from the red, and the snout is red. The rhymes red touch yellow, kill a fellow and red on black, friend of Jack encode this. Outside that region the rule is unreliable, because coral snakes elsewhere come in many patterns, some with no yellow at all and some that the mimics copy very closely, so identification by colour alone should never be trusted to justify handling the snake.
Why would a harmless snake evolve to look venomous?
It is a strategy called Batesian mimicry. A predator that has learned, by instinct or from a bad experience, to avoid the coral snake's bold ring pattern will also avoid anything that looks like it, so a harmless snake that happens to resemble a coral snake is attacked less and survives to breed more often. Over generations, selection sharpens the resemblance. The mimicry works best where real coral snakes are common enough that predators keep learning the lesson, and experiments with painted model snakes show that wild predators in coral snake country do avoid the ringed pattern, and avoid it less where coral snakes are absent. The kingsnake gets protection for free, without the cost of making venom.
Do kingsnakes really eat coral snakes?
Yes. Kingsnakes are ophiophagous, meaning they specialise in eating other snakes, and their diet includes venomous species, rattlesnakes and copperheads among them, which they can tackle because they are largely resistant to pit viper venom. Coral snakes, being smaller, are also on the menu where the two overlap, though a coral snake's neurotoxic elapid venom is chemically different from a pit viper's, and how completely kingsnakes resist it is less well studied. There is a certain irony in a snake that both imitates the coral snake for protection and, in the kingsnake's case, preys on it.