• Carrie Gardner

Venomous Snakes in the United States

Updated: Mar 29, 2020

Since we are now officially getting into venomous territory, it’s time for a friendly discussion on an all too common problem when it comes to these creatures. Though they are commonly referred to as “poisonous”, they are really not.

Poisonous animals are passive in how they introduce toxins. Amphibians, for example, will cover their bodies with poisonous secretions. If an animal tries to eat them, they will get the poison in their mouths. If a human picks it up, the skin will become irritated, but it will do the most damage is eyes, nose, or mouth are touched, since that introduces it to the system.

Venomous animals can bite or sting to envenomate. They don’t need to wait until they are touched (and hope the toxin is introduced to the mucous membranes around the face), they can actively defend themselves. If you touch a rattlesnake, you won’t get poisoned unless it takes umbrage to that and bites.

I realize that it's not a matter of life and death with whether or not a snake is poisonous or venomous. But it's pretty cringe-worthy to those of us interested in snakes!

There are two types of venomous snakes in the United States - pit vipers and coral snakes. We can further break down the pit vipers into copperheads, water moccasins (or cottonmouth), common rattlesnakes, and ground rattlesnakes.

Pit vipers have a large pit in their faces roughly between the nostrils and eyes. These pits are highly sensitive heat sensing pits that give them an infrared image much like an infrared camera. Since they hunt primarily at night, They are ambush predators that hang out next to rodent trails. The heat signature off their prey allows the snake enough time to strike. The envenomated animal is allowed to continue on. In a few minutes, the snake goes after it, using the scent of it’s venom to follow. Dinner has already passed on and the snake’s venom is already working on digesting.

Studies have been done that demonstrates the snake can accurately hunt even with their eyes covered without any hesitation. When that was reversed with the heat pits covered, it took them much longer. All snakes are blessed with a spectacular sense of smell. They catch air molecules with their tongue, which is why it’s always flicking in and out. Eventually the snake with the pits covered were eventually able to catch the mouse with smell. Studies showed that they can tell a difference in temperature as small as 3/1000s of a degree.

Most pythons and boas also have heat pits, except they have three or four on their upper lips - called labial pits. I always wonder what my ball python sees when he looks at me.

Pit vipers are heavy-bodied snakes with a reluctance to share their venom with anyone but their dinners. The largest rattlesnake in the country is the Eastern diamondback rattlesnake.

I see a lot of websites rate venomous snakes on their aggressiveness. I personally have a problem with that. If you were to do a search snakes that chase on YouTube, you would see a bunch of videos showing "extremely aggressive" water moccasins - juveniles even allowing people (I'm hoping professionals) to walk right up to them and allowing a foot to be put up on their body without even a hiss or strike. In the mean time, I had to work with my baby ball python for a couple of months before he stopped biting me - and they have a sweet gentle reputation. So here's my theory, for what it's worth. Snakes are like other animals and they have their own personalities with their own limitations and reactions to stress. Younger snakes, like my ball python, tend to be more aggressive because of their tender age. Also, the activity level of a snake depends on how warm they are. Warmer snakes will be more feisty.

Besides the pit vipers, we have three species of coral snakes, found mostly in the southern states.

According to Venom Byte - Venomous Snakes by State, Arizona has the most species of venomous snakes, at 19. Click on the link to find out how many your state has! If you’re in can just read the next page - where I get descriptive.

Because all but three venomous snakes are pit vipers in the United States, the same antivenin is used to treat all viper bites - CroFab. Released in 2000, it is derived from sheep using the venom of the eastern diamondback, western diamondback, Mojave rattlesnake, copperhead, and cottonmouth snakes. In 95% of those treated, there was a clinical response in less than an hour. While it costs about $100.00 - $400.00 a vial in Mexico, because they recognize that snakebites are a public health concern, in the U.S., the suppliers charge $2300.00 - $2800.00 to hospitals. Hospitals then hike it up anywhere from $14,000 - $20,000 per vial. They say that they charge that as a way to open up negotiation with insurance companies, however, if the patient doesn’t have insurance or has a high drug deductible has to negotiate for themselves. So, if you see a snake, walk away and go spend the $100,000.00 that you would’ve had to pay a hospital for treatment on something fun! *Late 2019, a new antivenin was released that is less expensive and stays in the body longer. Anavip was approved for the use on rattlesnakes only, though. A vial costs $1,200 a piece but I'm not sure how many are required.

There is currently problems with producing coral snake antivenin. Tampa General Hospital is in close contact with the FDA and Wyeth/Pfizer to remedy the situation. Here is more information: Coral Snake Antivenin Information.

And finally...the list! I've included the scientific binomial or trinomial names. Every animal and plant are identified by a Latin name, my fellow Homo sapiens. Common names can apply to more than one snake. It comes in handy when you want an exact identification.

Pit Vipers


Broad-Banded Copperhead -Agkistrodon contortrix laticinctus

Northern Copperhead - Agkistrodon contortrix mokasen

Osage Copperhead - Agkistrodon contortrix phaeogaster

Southern Copperhead - Agkistrodon contortrix contortrix

Trans-Pecos Copperhead - Agkistrodon contortrix pictigaster


Eastern Cottonmouth - Agkistrodon piscivorus piscivorus

Florida Cottonmouth - Agkistrodon piscivorus conanti

Western Cottonmouth - Agkistrodon piscivorus leucostoma


Animas Ridgenose Rattlesnake - Crotalus willardi obscurus

Arizona Black Rattlesnake - Crotalus oreganus cerberus

Arizona Ridgenose Rattlesnake - Crotalus willardi willardi

Banded Rock Rattlesnake - Crotalus lepidus klauberi

Colorado Desert Sidewinder - Crotalus cerastes laterorepens

Eastern Diamondback Rattlesnake - Crotalus adamanteus

Grand Canyon Rattlesnake - Crotalus oreganus abyssus

Great Basin Rattlesnake - Crotalus oreganus lutosus

Hopi Rattlesnake - Crotalus viridis nuntius

Midget Faded Rattlesnake - Crotalus oreganus concolor

Mojave Desert Sidewinder - Crotalus cerastes cerastes

Mojave Rattlesnake - Crotalus scutulatus

Mottled Rock Rattlesnake - Crotalus lepidus lepidus

Northern Black-tailed Rattlesnake - Crotalus molossus molossus

Northern Pacific Rattlesnake - Crotalus oreganus oreganus

Panamint Speckled Rattlesnake - Crotalus mitchellii stephensi

Prairie Rattlesnake - Crotalus viridis viridis

Red Diamond Rattlesnake - Crotalus ruber

Sonoran Desert Sidewinder - Crotalus cerastes cercobombus

Southern Pacific Rattlesnake - Crotalus oreganus helleri

Southwestern Speckled Rattlesnake - Crotalus mitchellii pyrrhus

Tiger Rattlesnake - Crotalus tigris

Timber Rattlesnake - Crotalus horridus

Canebrake Rattlesnake - Crotalus horridus atricaudatus

Western Diamondback Rattlesnake - Crotalus atrox

Western Twin Spotted Rattlesnake - Crotalus pricei pricei

Ground Rattlesnakes

Western Massasauga - Sistrurus catenatus tergeminus

Eastern Massasauga - Sistrurus catenatus catenatus

Desert Massasauga - Sistrurus catenatus edwardsii

Dusky Pygmy Rattlesnake - Sistrurus miliarius barbouri

Carolina Pygmy Rattlesnake - Sistrurus miliarius miliarius

Western Pygmy Rattlesnake - Sistrurus miliarius streckeri


Coral Snakes

Arizona Coral Snake - Micruroides euryxanthus euryxanthus

Eastern Coral Snake - Micrurus fulvius (pictured below)

Texas Coral Snake - Micrurus tener

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