Thanks to its vast area, North America is home to 21 of the world’s most venomous species of snakes. The vastness and varied environments and weather conditions have made it possible for a variety of poisonous snakes to thrive as arid, semi-aquatic, amphibious and terrestrial creatures.
This article lists the top nine most venomous snakes, in no particular order, along with their habitats and identifying marks so you can give them a wide berth.
1. Eastern Diamondback Rattlesnake
This is the largest venomous snake you’ll find in the Americas, and could well be the largest venomous snake in the world. Some specimens have been found to measure nearly eight feet in length, weighing over 35 pounds.
It’s quite dangerous to humans, with about 10-20% of bite cases resulting in death. More dangerously, this snake’s bite distance is nearly a third of its length.
The Diamondback is quite easy to identify, with clearly visible, black diamond-like shapes running all along its back. Its size relative to other snakes is characteristic of this snake, apart from its bony rattle at the end, a rattle that it usually sounds before striking.
Don’t rely on hearing this species, or any rattlesnake, to give fair warning, since they’ve been known to strike even without rattling.
Probably the most visibly terrifying feature of this snake is its fangs – at 1 inch long, they are menacing and can pump its victims with as much as 450 mg (0.015 ounces) of its venom in one bite; only 150 mg (0.005 ounces) is enough to kill a person.
Habitat: The Eastern Diamondback makes its home in the pine forests, mountains, dry marshes and coastal areas of Florida, and in the lower southeastern states.
It rarely wanders into urban areas, but it’s not uncommon for it to go into houses to seek warmth and food if its habitat has been “invaded” by humans.
2. Western Diamondback Rattlesnake
Not quite as massive as its eastern cousin, the Western Diamondback is no less dangerous. Its venom may not be as lethal as the Eastern Diamondback, but it more than makes up for it by producing its venom in massive quantities.
Its bite can deliver a venomous dosage of as much as 800 mg (0.027 ounce), nearly twice its larger cousin.
A bite from the Western Diamondback results in massive internal bleeding and severe muscle damage. Fatality rates are the same as the Eastern Diamondback, with up to 20% of cases resulting in death.
As with its Eastern counterpart, the Western Diamondback Rattlesnake has the classic diamond shapes that line its back, only its “base” color is an almost tan-like brown, with cream-colored borders on its diamond patterns.
It likewise has a bony rattle at the end of its tail to warn of its impending strike.
This snake can grow to lengths of up to 7 feet and weigh 15 pounds, but most specimens encountered are 4 to 5 feet long and weigh just under 10 pounds.
This is the most aggressive of all the rattlesnakes, and its victims would have exceeded the record of its Eastern relative, were it not for it preferring sparsely-populated areas.
This rattler favors sandy, sun-bleached desert, salt marshes and rocky mountains. Its habitat ranges from southeastern California to Mexico, and halfway to Canada. Due to its range, it’s the snake responsible for most venomous snakebite fatalities in Mexico.
3. The Coral Snake (Eastern and Western)
Both the Eastern and Western types of coral snake share many similarities, such as potency of venom, color, and habitat. Its venom is extremely potent, with only 4-5mg (0.0001 ounces) able to seriously injure or kill an adult human.
Despite their lethality, both types are primarily nocturnal and usually avoid making contact with humans. Apart from habitat, their differences lie in size; the Eastern coral snake can grow up to 3 ⅓ feet long, while the Western coral snake on average is 2 feet long, with some specimens reaching barely over 2 ½ feet.
Coral snakes don’t bite like other snakes; their bite entails a longer “process” where they hang onto the victim and make a chewing-like action to deliver venom. Their venom is a neurotoxin, meaning it directly affects the brain, causing paralysis and respiratory failure.
Symptoms don’t manifest immediately, but begin with slurred speech, double vision and muscular paralysis.
Victims usually have one hour after being bitten to seek medical attention. Currently there is no antivenin for coral snake venom, as the company that manufactured the product, Wyeth Pharma, discontinued its production for economic reasons.
Luckily, coral snake encounters are quite rare, and their bites don’t always contain venom. In 40% of cases reported, little or no venom was injected into the victims, with only a single coral snakebite death in over 40 years.
The Coral snake has distinct “banding” of colors, consisting of black on the head, followed by yellow, red, yellow, black then yellow, alternating and continuing until the tip of the tail. To tell if the banded snake is really a coral snake, observe the red band.
If it’s between yellow bands, it’s definitely a coral snake. If its red bands are in between black, it’s a Scarlet King snake, a non-poisonous “impostor”.
To make it easier to tell them apart, remember this rhyme: “Red touch yellow, kill a fellow” for Coral snakes and “Red touch black, friend of Jack” for the King snake.
Due to its nocturnal nature, this snake is hardly ever seen in broad daylight. The Western Coral snake prefers the dry, rocky environment of the desert, while its Eastern cousin burrows under leafy forested areas. Neither snake hunts mammals, preferring to eat small lizards, insects and other snakes.
4. The Copperhead
Named precisely for its copper-colored head, this snake is one of the most misidentified snakes in North America. When frightened or startled, it may appear to “freeze” in position, relying on its camouflage to keep it safe until the cause of its distress leaves.
Ironically, its camo is so effective that people accidentally step on or near it, prompting the snake to bite in self-defense. Its first bite is usually non-venomous and serves as a “warning”, but if it still feels threatened, its second bite will most definitely deliver venom.
Its venom isn’t potent enough to kill, but muscle degradation may necessitate amputation at the bite area. Fatalities result indirectly from a copperhead’s bite; some people develop fatal allergic reactions to its antivenin.
The copperhead is often mistaken for a non-poisonous snake, which could be the cause of it being handled or dealt with improperly and lead to getting bitten.
A stout snake that grows to lengths of up to 1 ½ to 3 feet, this medium-sized serpent is brownish to reddish in color, with hourglass-shaped bands all along its length.
Its color is a lot like that of dead leaves, giving it superior camouflage when it’s out during the fall or early summer season. Another unmistakable feature of the Copperhead is its heart-shaped head.
Copperheads can be found as far north as New York on the eastern seaboard, to as far inland as Nebraska. You may encounter it in daytime at forested areas. Be wary of areas that have dried leaves, such as in your back yard or in public parks.
5. The Cottonmouth
Also known as the Water Moccasin, the cottonmouth is closely related to the copperhead, except it has a semi-aquatic nature. Cottonmouths are more aggressive, but bite only when touched.
When threatened, it will hiss and go into a strike-ready pose, then open its mouth wide, exposing its mouth’s very white lining, hence its name. Its venom is a hemotoxin, meaning it breaks down blood cells and prevents blood from coagulating and clotting.
Victims who don’t get immediate, proper treatment can suffer from hemorrhaging wherever the venom has spread, and extreme pain will be felt at the bite site.
Temporary or permanent muscle damage can occur, requiring amputation of extremities like fingers or toes, depending on the location of the bite.
The Cottonmouth is larger than its copperhead cousin, measuring anywhere from 3 to 6 feet in length. Apart from its white-colored mouth, this snake has telltale dark stripes that trail behind its eyes.
Adult Cottonmouths are dark tan, brown, or almost black, with barely-visible black or dark brown crossbands. Their underbellies are paler than their backs. Like most venomous snakes, Cottonmouths have cat-like pupils in their eyes, and its head is triangular or heart-shaped.
Being semi-aquatic, the Cottonmouth inhabits the southeastern states, from southern Virginia to Florida, and eastern Texas. It eats frogs, small fish, birds, baby alligators, turtles, and lizards.
It’s also cannibalistic in that it eats other snakes, including smaller Cottonmouths. Its hunting grounds consist of marshes, swamps, drains, and the edges of ponds, lakes and rivers.
6. Yellow-Bellied Sea Snake
Under “normal” conditions, this snake should not have made the list of poisonous snakes in North America. As recently as October 2015, the Yellow-Bellied sea snake has been sighted as far as the beaches of Ventura County, California, well outside their usual range.
Climate change phenomena such as El Niño and severe storms have brought these snakes to the relatively colder waters of California. As of now, no fatalities in North America from the bite of this newcomer have been reported, though its venom is potentially lethal.
Only .067mg (0.000002 ounces) of its venom is needed to kill a person, and on average its bite delivers 4mg (0.0001 ounces) of poison.
As the name implies, the yellow-bellied sea snake has a bright yellow or pale brown underbelly, along with a black or dark brown upper body, with the colors having a clear demarcation.
Some specimens that are entirely yellow, or with black mottling or a thin black stripe running along the belly also exist. Females of this species can grow as long as nearly 3 feet, while males will mostly reach lengths of a little over 3 feet, but never reaching 3 ½ feet. Due to its aquatic nature, this snake’s tail ends in a fin, much like a Giant Eel.
The yellowbelly has a massive range that spans practically all the world’s oceans except for the Atlantic and the Mediterranean. More common in the Pacific Ocean, the Yellowbelly rarely comes ashore, as it’s not particularly well-adapted to living or hunting on land.
On the few occasions that it goes to tidal pools, it only does so to birth its young. It can’t thrive in freshwater and feeds almost entirely on fish.
7. Timber Rattlesnake
The timber rattler is historically the most well-known of the rattlesnakes among early settlers of North America, and while it still thrives in some densely-populated states, it’s virtually extinct in others.
Just like other rattlers, the Timber rattlesnake delivers a considerable amount of venom in a single, quick strike. Its unusual characteristic is that its venom actually varies per region.
Timber rattlers in the northeast states have venom that is hemorrhagic, while the more southern specimens contain more neurotoxin. Specimens between the regions contain a mixture of both, making their venom highly toxic.
Timber rattlers can grow to more than 5 feet, with the largest recorded specimen a few inches over 6 feet in length, and can weigh as much as 10 pounds.
Typically adults will measure around 3 ½ feet. As with their venom, their colors vary per region. Look for a V- or W-shaped pattern on their backs, and their colors can vary from a base gray color with a rich black pattern, a tan base color with a golden yellow pattern, and a mixture of black and yellow base colors and patterns.
The Timber Rattlesnake was common to the northeastern states all the way to Canada, but has become extinct in Ottawa, Rhode Island, Maine, and are is in much smaller numbers in New Hampshire.
As an ambush hunter, this snake preys mostly on rabbits, birds and small rodents. This rattler prefers to lie in wait in similarly-colored forest floor and can be extremely difficult to spot, so caution is advised when hiking or camping.
8. Mojave Rattlesnake
Although not the biggest rattlesnake, the Mojave has gained the reputation for being the most aggressive to humans. Its venom is highly toxic, and is a dangerous mix of neurotoxin and blood cell-destroying hemophagic elements.
It looks strikingly similar to the Western Diamondback, but some specimens lean towards a greener shade, hence its alternative name “Mojave Green Rattlesnake”.
You’ll find that the Mojave rattler looks every bit like a Western Diamondback, with a couple of exceptions: its base color is a shade of green, and on the tail section right before its bony rattle, that part has a “coontail” pattern – an alternating series of white and black bands.
In some cases there aren’t any “coontails” on a Mojave green, so the rule of thumb is that if the light and dark bands are roughly equal, it’s a Western Diamondback. If the white or light bands are wider than the black or dark bands, you have a Mojave.
In terms of size, the Mojave averages a length of just under 3 feet, and are relatively stout, with the thickest part of its body in its center. The neck is usually narrow and its head heart or shovel-shaped like its other rattler cousins.
Mojaves are limited to the southern areas of Arizona, California, New Mexico, Utah and parts of Texas. It prefers sandy, desert environs with sparse vegetation. They eat lizards, small mammals, rabbits and other snakes.
9. Massasauga Rattlesnake
This is probably the smallest of all the rattlers, measuring only 2 feet, on average. There have been specimens that measure at most 2 ½ feet, and rarely longer. Also known as the black rattlesnake for obvious reasons, the Massasauga rattler’s venom is moderately toxic, although this makes it no less dangerous, as its specific antivenin is rare.
Thankfully, there have been no recent fatalities among those treated with “generic” antivenin when bitten by this snake, so treatment is available and effective.
The Massasauga or Black Rattlesnake is mostly black or grayish brown in color, and has the same features as other rattlesnakes – the narrow neck, vertical, cat-like pupils, heart-shaped head and signature rattle at the end of its tail.
Some Massasauga rattlers appear almost completely black with the V- or W-shaped patterns on the back barely distinguishable, while others have clearly discernible black blotches bordered by white along the length of their backs.
Black Rattlesnakes can be found in Ontario, Michigan, the upper Missouri valley and in Colorado all the way to Mexico. They prefer to feed on small mammals, lizards, smaller snakes, insects and feed on frogs more than other rattlers.
Their favored habitats consist of marsh and grassy areas, and rarely habituate any terrain over 1,500 feet. They’re relatively less aggressive to humans, but will strike if threatened.
What to do if bitten
If you get bitten by any of these snakes, NEVER try to capture or kill the snake that bit you; this is a complete waste of time. The snake may simply escape, or bite you or anyone else who tries to capture or kill the snake, and the situation will only get worse.
Call 911 or get to a hospital as soon as you can. Doctors don’t need to see the snake to apply treatment, all they need is an accurate description of the snake’s appearance.
Most snakebites take an hour before the symptoms manifest and do serious damage to your body, so time is of the essence.
Don’t wait for the symptoms to show or allow the venom to venture deeper into your body; if the venom is left to reach your vital organs via your bloodstream, you could die in excruciating pain. Get to a hospital and get treated as quick as possible!
You’ve likely seen old movies where a person gets bitten by a snake, then another person cuts an “X” over the puncture wounds, then sucks out the poison with his mouth, then spits out the venom, saving the victim’s life. This is all a lie.
There are simply no effective first-aid procedures for snakebite. The best you can do while getting the victim to a doctor or hospital is to elevate the bitten area if possible, and keep the victim calm. Also:
- Don’t give the victim any alcohol; intoxication will make it difficult for them to relay info about the snake.
- Don’t let the victim drink caffeinated or energy drinks; this will speed up their pulse and spread the venom to other parts of the body more quickly.
- If they have to drink, give them water.
An ounce of prevention is worth a pound of cure, and snakebites are no exception. Be careful and cautious when hiking or camping, and when faced with a snake, don’t panic.
Identify where the snake is, and back off calmly. Remember that most snakes generally fear other creatures, and bite as a means of defense.
Never disrespect or try to kill them unless it’s for your survival; many snakes like the Timber rattler and Massasauga rattler are considered endangered species in some states, and killing them for no valid reason may even get you jail time. Never ignore a bite, and seek medical assistance ASAP.