Eastern Coral Snake (Micrurus fulvius): Facts and Venom

Appearance

The eastern coral snake is easy to recognize once you know what to look for. Its body is circled by wide red and wide black rings, separated by narrow yellow rings, so that the red rings always touch yellow ones. The rings run all the way around the body, including the belly, and the red rings are usually freckled with small black spots.

The head is small, blunt and hardly wider than the neck. It is black from the tip of the snout to just behind the eyes, followed by a broad yellow band across the back of the head. The tail carries only black and yellow rings, with no red. The scales are smooth and glossy, and the eyes are small, with round pupils.

Young coral snakes have the same pattern as adults, but their red rings are paler and darken with each shed. Rare individuals with unusual coloring have been recorded, which is one reason the famous rhyme about ring colors is not a perfect test. Read more in does the “red touches yellow” rhyme work?

Size

Most adult eastern coral snakes measure 50 to 80 cm (20 to 31 in) from snout to tail tip, and they are thin, roughly as thick as a finger. The largest reliably recorded specimen, from Florida, measured about 122 cm (48 in), and there is a report of one about 130 cm (51 in) long. Snakes from Florida tend to be larger than those elsewhere in the range.

Females grow to a greater total length than males, while males have proportionally longer tails. Weights are rarely recorded, but even large adults are light, well under 0.5 kg (1 lb).

Habitat and range

The eastern coral snake lives on the coastal plain of the southeastern United States. Its range runs from southeastern North Carolina through South Carolina, southern Georgia and all of Florida, and west through southern Alabama and Mississippi to eastern Louisiana, east of the Mississippi River. It is found from near sea level up to about 400 m (1,300 ft).

It favors places with sandy soil and plenty of cover: longleaf and slash pine flatwoods, sandhills, oak scrub, hardwood hammocks (islands of trees surrounded by wetter ground) and the edges of wetlands. In Florida it also turns up in leafy suburban yards and gardens. What matters most is loose soil, fallen leaves, logs and old root channels that let it move and hunt out of sight.

In North Carolina it reaches the northern edge of its range and is rare. Climate models suggest that its range could shift northward as winters grow milder.

The Texas coral snake split

For many years, coral snakes from Texas, western Louisiana and southern Arkansas were treated as a subspecies of the eastern coral snake. Most herpetologists now recognize them as a separate species, the Texas coral snake (Micrurus tener), which also ranges into northeastern and central Mexico. It looks very similar, with the same red, yellow and black rings, but tends to be a little larger and stouter and has a somewhat larger venom yield.

A third species, the Sonoran or Arizona coral snake (Micruroides euryxanthus), lives in Arizona, southwestern New Mexico and northwestern Mexico. It is smaller and belongs to a different genus. Together these three are the only coral snakes in the United States. See how they fit among other species in venomous snakes in the US.

Diet and hunting

Eastern coral snakes are specialist predators of long, thin reptiles. Most of their prey are other snakes, especially small burrowing species, along with slender lizards such as skinks and legless glass lizards. Frogs, insects and small mammals are eaten only occasionally. In Texas, the closely related Texas coral snake has even been recorded eating copperheads and other coral snakes.

A hunting coral snake moves slowly through leaf litter, flicking its tongue to follow scent trails and pushing its head into crevices and leaf piles. When it finds prey, it bites, usually near the head, and holds on while its neurotoxic venom paralyzes the victim. It then swallows the prey whole and head first, a sensible approach for prey that is nearly as long as the predator.

Coral snakes eat infrequently, with gaps of a few days to about three weeks between meals. Females feed most heavily from late summer into fall, after laying their eggs.

Behavior

This is a secretive, mostly underground snake. It spends much of its life in burrows dug by other animals, under logs and inside rotting stumps and leaf piles. Unlike many snakes, it is active mainly by day, especially in the morning and late afternoon, and it is most often seen above ground in spring and fall or after heavy rain has soaked the soil. During the coldest weeks of winter it becomes inactive.

Males travel the most in spring, from about March to May, as they search for females by following scent. Females are more active from late summer through fall, when they hunt to rebuild their reserves.

When discovered, a coral snake usually tries to escape. If it cannot, it may flatten its body, hide its head under its coils and raise its curled tail, which looks like a head, so that a predator strikes the wrong end. It may also thrash erratically, and it will bite if it is grabbed or pinned.

Reproduction and life cycle

Eastern coral snakes mate mainly in spring, from March to May, and sometimes again in fall. Several males may gather around a single female. Females can store sperm for months.

In June or July the female lays a single clutch of about 2 to 12 eggs, 7 on average, in an underground tunnel, a rotting log or a moist pile of leaves. The eggs are white, soft-shelled and unusually long and narrow, about 38 mm (1.5 in) long. They incubate for roughly 7 to 13 weeks, hatching in August or September. The mother does not guard them, and the hatchlings are independent from the start.

Coral snakes are the only venomous snakes in the United States that lay eggs. Rattlesnakes, copperheads and cottonmouths all give birth to live young. Young coral snakes grow quickly and can breed within about one to two years. Lifespan in the wild is poorly known; captive coral snakes live about 7 years on average, and an individual 13 years old has been reported.

Venom and danger to people

The eastern coral snake belongs to the family Elapidae, the group that includes cobras, mambas and sea snakes. Its venom is mainly neurotoxic, meaning it blocks the signals that nerves send to muscles. It is delivered through a pair of short, fixed fangs at the front of the upper jaw, and laboratory tests rank it among the most potent snake venoms in North America.

Bites, however, are uncommon. Coral snakes account for less than 1 percent of venomous snakebites in the United States, and most bites happen when people pick up or handle the snake. Symptoms can be delayed for several hours, so a bite that seems minor can still become serious. Anyone bitten should seek emergency medical help immediately: call 911. The full story is in how venomous are coral snakes?

Predators, threats and conservation

Despite their warning colors, coral snakes have many enemies. The eastern indigo snake, kingsnakes and racers eat them, as do birds such as red-shouldered hawks and loggerhead shrikes. Domestic cats and American bullfrogs occasionally kill them, and invasive red imported fire ants attack eggs and hatchlings.

The IUCN Red List classes the eastern coral snake as Least Concern, because it remains widespread, especially in Florida. Locally the picture is different. It is listed as Endangered by the state of North Carolina and is considered of high conservation concern in Alabama. The main threats are the loss of longleaf pine forests and sandhills to development and farming, deaths on roads, illegal collection and killing by people who fear snakes.

Myths and facts

Myth: coral snakes must chew to inject venom. They often hold on and make chewing motions, which helps the small fangs work, but a quick bite can still deliver venom.

Myth: coral snakes are aggressive. They are among the shyest snakes in North America and almost always try to flee.

Myth: you can always spot a venomous snake by its slit pupils or triangular head. Coral snakes have round pupils and a narrow, rounded head, so these rules of thumb fail completely here.

Myth: any red, yellow and black snake is a coral snake. In the Southeast, harmless mimics such as the scarlet kingsnake share the colors in a different order. Learn the differences in coral snake vs scarlet kingsnake, and remember that the safest choice is to leave any ringed snake alone.