Reptiles
Coral Snake
Micrurus and Micruroides · also called coralsnake
A coral snake carries some of the most potent venom of any North American snake and almost never uses it on a person. Its fangs are tiny and fixed, so it has to grip and chew rather than strike, and it is a shy burrower that would much rather be left alone. Its bold red, yellow, and black rings are a warning — one so effective that several harmless snakes have copied it.
Overview
Coral snakes are brightly banded elapids — the cobra family — with around 80 species in the Americas (genera Micrurus and Micruroides) and a separate group of Old World coral snakes in Asia. They are small, secretive burrowers of forest floor and leaf litter, and carnivores that eat mostly other snakes. All have short fixed fangs and neurotoxic venom.
The warning, and the mimics
The rings of red, yellow or white, and black advertise danger, and the signal works so well that the harmless scarlet kingsnake and milk snake have evolved nearly identical patterns. The rhyme “red touch yellow, kill a fellow” describes the band order in the southeastern US only — it fails entirely for coral snakes further south.
Small fangs, slow venom
With tiny fixed fangs, a coral snake must grip and chew to inject venom, so many defensive bites are dry or mild. A serious bite may cause little pain at first, with drooping eyelids, slurred speech, and breathing difficulty developing over hours — so every suspected bite is treated as an emergency.
Status
Coral snakes as a group are Not Evaluated, and their secretive habits make them hard to survey. Most are thought to be reasonably common, though some Central and South American forest species are likely declining with deforestation, and data are generally poor.
Coral Snake: common questions
How do you tell a coral snake from a harmless mimic?
In the southeastern United States, and only there, the order of the coloured bands is a reliable guide. On a true coral snake the red and yellow bands touch, and the snake also has a black snout, whereas on the harmless scarlet kingsnake and scarlet snake the red bands touch black, and the snout is red. The rhymes red touch yellow, kill a fellow and red on black, venom lack capture this. Outside that region the rule is useless, since coral snakes in Mexico, Central America, and South America come in many band patterns, some without yellow at all, and some mimics there are very convincing. The safest approach anywhere is to not handle any small banded snake.
How dangerous is a coral snake bite?
The venom is extremely potent, drop for drop among the most toxic of North American snakes, and an untreated serious bite can kill by paralysing the muscles used for breathing. However, coral snakes are responsible for only about 1 per cent of venomous snakebites in the United States and there have been very few deaths in the era of antivenom. This is because the snakes are shy and rarely encountered, they must chew to deliver venom through their small fixed fangs so many bites are dry or mild, and the ones that do inject venom usually involve someone deliberately picking the snake up. Any suspected coral snake bite is a medical emergency because symptoms can be delayed for hours.
Are coral snakes related to cobras?
Yes. Coral snakes belong to the family Elapidae, the same family as cobras, mambas, kraits, taipans, and sea snakes. Members of this family share short, fixed fangs at the front of the upper jaw and venom that is mainly neurotoxic, attacking the nervous system rather than destroying tissue as viper venom does. Coral snakes are essentially small, burrowing, brightly banded New World elapids that specialise in eating other snakes. There is also a separate lineage of Asian coral snakes and the African and Asian relatives, so the coral snake body plan and colour scheme have appeared more than once within the family.
Why are coral snakes so brightly coloured?
The rings of red, yellow, and black are a warning signal, called aposematism, telling predators that the snake is dangerous and not worth attacking. A predator that survives one bad experience with a coral snake, or that is born with an instinct to avoid the pattern, learns to leave anything with those bands alone. This protection is strong enough that it has been worth copying, and several harmless snakes have evolved to look almost identical, freeloading on the coral snake's reputation. Experiments with painted model snakes show that wild predators in coral snake country do avoid the ringed pattern, and avoid it less in areas where real coral snakes are absent.