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Top Tips on How to Identify a Poisonous Snake

February 21, 2017
How to identify a poisonous snake

Poisonous snakes can be found in most parts of the world, but how can you tell the difference between venomous and non-venomous snakes? They don’t exactly come equipped with warnings signs – or do they? If you know what to look for, you can identify a poisonous snake out the wild and know whether it’s time to run for cover, or breathe a sigh of relief. We’re going to look at venomous snakes around the world and give you tips on how to identify these creatures.

4 Types of Venomous Snakes in the United States

There are four types of venomous snakes in the United States: cottonmouths, copperheads, rattlesnakes and coral snakes. Each has its own unique appearance and characteristics.

1. Cottonmouths

Cottonmouths are sometimes referred to as water moccasins, and they’re commonly found in the southeastern United States. This species of pit viper can deliver a painful and sometimes deadly bite. These snakes are the only semi-aquatic pit vipers on the planet, and they’re commonly found near lakes, streams, marshes and other bodies of water. Cottonmouths are very strong swimmers and may even enter the sea.

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【Read more about Cottonmouths】

Appearance and Behavior

The cottonmouth snake is the largest species in the Agkistrodon species. Adults average around 31 inches in length, but some may exceed 71 inches in the eastern United States.

Cottonmouths have a very distinct appearance, which makes them relatively easy to identify in the wild.

  • They have broad heads with thin necks.
  • Their snouts have a blunt profile.
  • The top rim of the head extends slightly further than the mouth.

As far as coloring goes, most cottonmouth are almost entirely black in color with the exception of facial and head markings.

They may also have the following background colors:

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  • Gray
  • Brown
  • Tan
  • Yellow-olive

Most of these snakes have 10-17 crossbands that are either black or dark brown in color with black edges. Their dorsal markings tend to fade with age.

Juveniles have yellowish tails, subadults have greenish colored tails and adults have black tails.

Cottonmouths are often confused with copperhead snakes (another venomous snake), but there are some distinct differences between the two:

  • Cottonmouths have dark, broad stripes along the sides of their heads that extend from the eyes.
  • Copperheads have a dark, thin line that divide the scales along the jaw from darker color on the rest of the head.

Just like any other snake, the cottonmouth snake will coil and posture when it goes on the defensive. While they have a reputation for being aggressive, these snakes would prefer not to bite humans and only do so when they feel threatened.

Geographic Location

Cottonmouths are generally found in the southeastern United States from the Great Dismal Swamp in Virginia down to the Florida peninsula. They can also be found in Arkansas, southern Georgia, Oklahoma and eastern Texas.

So, if you’re living on the west coast and you happen to find a snake that has similar characteristics, you can be fairly certain that you’re not dealing with a cottonmouth snake.

2. Rattlesnakes

The rattlesnake is one of the most well-known poisonous snakes in North America, and they account for the majority of snakebite injuries in this region. Just like their name suggests, these snakes make a rattling noise when they feel threatened. A bite from a rattlesnake can be dangerous, but they’re rarely fatal – as long as you get prompt medical attention.

【Read more about Rattlesnake】

Appearance and Behavior

There are 29 species of rattlesnakes, and they all vary in appearance. As adults, they can be relatively large in size. The eastern diamondback is the longest rattlesnake, and can grow to be an impressive eight feet long. The twin-spotted rattlesnake is the smallest species and only grows to be about 12 inches long. Most species are between two and four feet long.

Rattlesnakes can vary greatly in weight. The eastern diamondback is the heaviest species and can weigh up to ten pounds. The lightest species is Crotalus willardi, which only weighs three to four ounces.

Just like other pit vipers, these snakes have heat-sensing pits on their faces, which allows them to locate and follow their prey. They also have vertical pupils, like cat eyes.

Rattlesnakes have hemotoxic venom, which prevents blood from clotting and causes necrosis. They feed on small animals, such as rodents and birds.

Geographic Location

Rattlesnakes can be found all throughout the Americas, from Canada to central Argentina. These predators can live in a wide range of habitats.

3. Copperheads

Copperheads are one of the most common venomous snake in North America, and they’re also the most aggressive. Thankfully, their venom is mild, so their bites are rarely fatal to humans.

Still, they are snakes to be respected and feared. Their venom may not be potent, but you still don’t want to be bit by one.

Appearance and Behavior

Just like their name suggests, copperheads have copper-colored heads. This venomous species is medium-sized and grows to be between two and three feet in length.

Females are usually longer than males, but males may have longer tails.

Copperheads have distinct patterns on their bodies. These snakes have reddish-brown or chestnut-colored dorsal crossbands that look like saddlebags, hourglasses or dumbbells.

While other venomous snakes may have similar patterns, the copperhead is the only species to have hourglass-shaped crossbands.

These snakes have white, yellow or light brown bellies with black, gray or brown spots or smudges. Their bodies are muscular and thick, and their scales are keeled. Their heads are shaped like an arrow and very distinct from their thin necks.

Copperheads have vertical pupils like cats’ eyes , and their irises may be tan, orange or reddish-brown.

Geographic Location

Copperhead snakes can be found in the eastern United States as well as Texas and some parts of the Midwest.

4. Coral snakes

Coral snakes are a type of elapid snake, and there are two groups of these snakes: New World and Old World. There are 16 species of the Old World coral snake and more than 65 species of the New World coral snake. Not all species of the coral snake are venomous.

New World coral snakes are dangerous, and have one of the most potent venoms among all snakes in North America. Thankfully, very few bites have been recorded in history because these snakes are reclusive and tend to hang out in places where humans don’t go.

【Read more about Coral Snake】

Appearance and Behavior

Coral snakes have distinct black, red and yellow/white banding. They’re relatively small in size. Most species in North America average three feet in length, but snakes up to five feet long have also been found.

The coral snake is not an aggressive species and will almost always try to flee. They only bite as a last resort, and their short fangs can’t penetrate thick clothing.

But if a coral snake does bite you, you need to seek medical attention immediately. Their venom is a powerful neurotoxin that will paralyze your respiratory muscles in just a few hours. Large amounts of antivenom and mechanical respiration are required to save a victim’s life.

One simple way to tell the difference between a venomous and non-venomous coral snake in the U.S. is to look at its colors.

There’s a famous coral snake rhyme that basically teaches us:

  • A red-yellow-black coral snake means it’s probably venomous.
  • Red and black means it’s probably a harmless snake.

These generalizations don’t apply to Old World coral snakes or New World coral snakes in South and Central America. Coral snakes eat other small snakes and lizards as well as frogs.

Geographic Location

Coral snakes tend to live in places sparsely populated by humans. They prefer the jungle or heavily forested areas, and they spend most of their time burrowed under the ground or underneath leaf piles.

Species of Old World coral snakes can be found in the following parts of the world:

  • India
  • Malaysia
  • Singapore
  • Thailand
  • Indonesia
  • Sri Lanka
  • Cambodia
  • Bangladesh
  • Vietnam
  • Laos
  • Taiwan
  • Nepal
  • Myanmar
  • China
  • Ryukyu Islands
  • Philippines

Species of the New World coral snake can be found in the following parts of the world:

  • Mexico
  • United States
  • Sinaloa
  • Nicaragua
  • Panama
  • Costa Rica
  • Argentina
  • Brazil
  • Uruguay
  • Columbia
  • Ecuador
  • Peru
  • Bolivia
  • Honduras
  • Venezuela

How to Identify a Venomous Snake

Knowing the four venomous snakes in the United States is helpful – if you live there, or are traveling there. But if you’re in any other part of the world, you may not know what to look or what types of snakes are poisonous.

Venomous snakes are different in their own ways, but do share some general characterisitics that can help you decide whether you’re face-to-face with a deadly foe.

1. Consider Color Patterns

Many creatures in nature have what we call “warning colors” to let us know that they are dangerous. This same theory applies to poisonous snakes. Many species have bright colors that warn us to stay away.

The deadly coral snake, for example, has red and yellow bands, which are two colors we associate with danger or caution. The copperhead snake is copper or red in color.

Of course, there are exceptions to this rule, and some brightly-colored snakes are absolutely harmless. But generally speaking, snakes of one color are not venomous.

2. Look at the Head Shape

Poisonous snakes usually have triangular heads, while non-venomous snakes usually have round heads. The triangular shape is caused by the venom glands. Some harmless snakes can flatten their heads as a defensive mechanism, which can make their heads look triangular. And some species of coral snakes may have rounded heads because their venom glands are less noticeable.

3. Does it Have a Rattle?

Rattlesnakes account for most snakebite injuries in North America, so if you happen to be in that neck of the woods, be on the lookout for a rattle at the end of the tail.

But don’t rely on the rattle alone when trying to identify a rattlesnake. These snakes develop their rattles as they shed their skin, and add on a new row of rattles with each shed. Younger poisonous snakes don’t have rattles, but they can be just as dangerous.

Sometimes, the rattle can wear away over time, so an older poisonous snake may not have a rattle either.

4. Does the Snake Have a Heat Pit?

Many venomous species of snakes belong to the pit viper family, which means they have heat-sensing pits on their heads. These pits help them detect and follow prey by sensing heat.

Not all venomous snakes are pit vipers, however. The coral snake doesn’t belong to this family and doesn’t have a heat-sensing pit. But it’s still a highly dangerous snake with a potentially fatal bite.

5. Be on the Lookout for Mimics

Some harmless species of snakes will mimic the patterns of venmous snakes to keep predators away. This smart tactic can help the species survive, but can also cause more humans to kill these non-venomous snakes. Non-venomous king and milk snakes look a lot like coral snakes. Rat snakes look like rattlesnakes.

The safe option is to treat every snake like it’s a venomous snake. Don’t try to handle it or get too close. Don’t kill snakes either unless in self-defense. Killing non-venomous snakes just allows the venomous snake population and the rodent population to grow.

6. Look at the Eyes

Many species of venomous snakes have vertical pupils that look like cat eyes. Round pupils are most commonly seen in non-venomous snakes.

7. Look for a Heat-Sensing Pit Between the Eyes and Nostrils

The heat sensing pit we talked about earlier can be found between the eyes and nostrils of a snake.

Remember, non-venomous snakes will not have these pits.

8. Notice the Underside Scales on the Tip of the Tail

The scales on the underside of the snake’s tail can help you tell whether the snake is venomous or harmless. Most species of venomous snakes have a single row of scales under the tail, whle non-venomous snakes usually have two.

9. Look at the Bottom of the Tail

If you can see the bottom of the snake’s tail, you may be able to tell whether it’s poisonous. Do not pick up the snake under any circumstances. With poisonous snakes, the bottom of the tail looks the same as the rest of the underbelly. If the snake has a diamond shape (or cross) pattern under its tail, it’s probably harmless. You probably won’t be able to check the bottom of the snake’s tail (not safely) unless it’s dead or hanging from a tree.

10. Watch Water Snakes Swim

There are both venomous and non-venomous species of water snakes. Only the venomous kind swims with its entire body visible on the water.

【Read more about Water Snake】

11. Examine the Bite Marks in Case of a Snake Attack

If you do happen to get bit by a snake, the bite marks may be able to tell you whether it was a venomous species.

A ragged bite mark usually indicates that the snake doesn’t have fangs, which means it’s not venomous.

But if you have two closely-set bite marks, it means the snake has fangs and is venomous.

Knowing the Exceptions

Just like anything else in life, there are exceptions to the venomous snake rules above.

Head Shapes Aren’t Always a Tell-Tale Sign

Most venomous snakes have triangular heads, but not all do. The coral snake has a round-shaped head, but is highly venomous and potentially deadly if the bite isn’t treated immediately. Also, some snakes may flatten their heads, which makes them look triangular, but they’re non-venomous.

Colorful Snakes are Sometimes Non-Venomous

Many species of venomous snakes are colorful, but there are some that are just black or brown. Other colorful species are completely harmless. The scarlet king snake, the scarlet snake, the red milk snake and the corn snake are all brightly colored but non-venomous. Some poisonous water snakes are almost entirely black.

Venomous Snakes Sometimes Have Round Pupils

Average venomous snakes have vertical pupils that look similar to a cat’s eye. But there are some venomous creatures that have round pupils, such as the inland taipan, the black mamba and the cobra.

Venomous Snakes from Other Countries

So far, we’ve focused mainly on venomous snakes in North America, but there are deadly species in other parts of the world, too. Let’s take a closer look at venomous snakes in other countries.

1. Snakes in the UK

The Dangerous Adder

The adder, or common viper, is common in the UK, but is mostly found in the southern region of the nation.

These snakes have distinctive X- or V-shaped markings on their heads. They also have vertical pupils and zigzag stripes on their backs.

The adder’s dark patches range from blue to gray and black. Its background color is usually gray, but can also be red or brown.

Adder bites aren’t usually fatal, but they do require immediate medical attention. Thankfully, these snakes aren’t aggressive unless they’re disturbed or threatened.

2. Snakes in India

India is home to a few species of venomous snakes, including:

The Common Cobra

Associated with snake charmers and snakes in a basket, the cobra is a dangerous snake. If you’re unlucky enough to get bitten by one, you’ll need to seek medical attention immediately.

The cobra’s potent venom is responsible for many deaths in India each year.

Cobras vary in size, from three to six feet in length. They have broad heads and can spread their hoods as a warning sign to stay away. Their colors can vary greatly depending on which part of India you’re in.

Cobras in northern India are usually black or dark brown, while cobras in southern India are usually brown or yellow.

While these creatures are usually shy and would prefer not to bite, the cobra can strike repeatedly and with extreme precision.

Common Krait

The krait snake is a large snake that can grow between four and six feet long. Like many other venomous snakes, the krait’s head is slightly broader than its neck. It has a depressed head with round snout. Its eyes are entirely black and small in size.

The krait’s color pattern is one of its most distinctive features. This snake’s body is black with white bands, and its scales are hexagonal.

Kraits prefer to hunt at night, and this is when they’re most aggressive. But if you happen to catch one out during the day, they tend to be more docile.

Russel’s Viper

The Russel’s viper snake is highly venomous and will whistle like a pressure cooker as a warning before it strikes. If you happen to get bit by one of these snakes, you’ll need to seek medical attention right away.

Russel’s vipers have triangular heads with two triangular spots. Its eyes have vertical pupils, and its tongue is dark purple.

The snake’s body has three rows of eye-shaped spots that are either black or brown in color.

Saw-Scaled Viper

One of the most common vipers in India, the saw-scaled viper varies in size (15″ to 30″ long) and comes in a variety of colors, from gray to red or dark brown.

These snakes are extremely aggressive if they’re provoked, so stay far away if you see one. When they feel threatened, these snakes will make a saw-like sound by rubbing their scales together.

This species has one the quickest strikes in the world.

3. Snakes in Australia

Australia is home to some of the deadliest snakes in the world. Two of the most dangerous include:

Fierce Snake

Also known as the Taipan, the Fierce snake is known as the most deadly snake on the planet. It has the most potent venom of any snake species, but here’s a surprising fact: there are no recorded deaths by this snake.

The Fierce snake can grow to be more than six feet long, and its color can vary from light straw to dark brown. Its color grows darker in the winter and lighter in the summer. The head of this snake can look black.

The Fierce snake can be found in the black soil plains near Queensland.

Eastern Brown Snake

The eastern brown snake causes the most snakebite deaths in Australia. These snakes would rather slither away than attack, but they will stand their ground if provoked.

This species of snake can grow to be six feet long, and can vary in color from dark brown to tan or gray. They have slender bellies with dark orange spots.

Not surprisingly, the eastern brown snake is found in eastern Australia. They live in woodland, grasslands and pastures.

If you happen to be bitten by one of these snakes, seek medical attention immediately.


Venomous snakes are highly dangerous creatures, but even with snake skin identification, it can be hard to tell whether the snake is poisonous until it’s too late. Snake experts recommend leaving any and all snakes you meet in the wild alone. And if you happen to have snakes in your yard or home, it’s best not to set a snake trap yourself and leave extermination to the experts.

【Watch this video about Venomous Snakes】

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