Venomous Snakes of Arkansas

By Renn Tumlison, tumlison@hsu.edu

 Venomous snakes use venom (specialized saliva) to capture their food. Six species of venomous snakes occur in Arkansas, but many harmless snakes are accused of being poisonous.

Coral Snake

 

 

 

 

 

The coral snake (Micrurus tener - pictured left), which is known from five counties in southern Arkansas, has neurotoxic venom that affects the nervous system of its prey. 

 

 

 

 

 

A non-venomous snake found in Arkansas, the milksnake (Lampropeltis triangulum - pictured center), has a similar color pattern to the coral snake.

Milksnake
Scarlet Snake

Also, another non-venomous snake called the scarlet snake (Cemophora coccinea - pictured right) is a harmless mimic of the coral snake. There is an old adage to help distinguish these poisonous versus harmless species (but it only works in North America):

Red and yellow kill a fellow,
Red and black venom lack.

Of the three above pictured snakes, notice that the coral snake has distinct red and yellow bands, but the other two "mimic species" have red markings bordered by black. 

 

 

 

The other five species of venomous snakes that occur in Arkansas have hemotoxic (=hemolytic) venom with proteins that break down tissue following injection into another animal. This venom facilitates capture of the snake's mammalian prey. These venomous snakes have another trait in common, a vertically elliptical pupil (this resembles a cat eye - see top photo of a copperhead). By contrast, most non-poisonous snakes have a round pupil, such as the black rat snake ( Elaphe obsoleta - bottom photo). Note: the coral snake also has a round pupil.

In addition, these five venomous snakes are known as "pit vipers." The pit is located between the nostril and the eye (the dark triangle in the top photo) and houses a heat-sensing organ, which allows pit vipers to "see" into the infrared portion of the electromagnetic spectrum. Infrared wavelengths are invisible to humans. With the aid of this heat-sensing pit, pit vipers locate rodents even at night (the heat given off by the rodent can be "seen" by the snake).

Blackrat and Copperhead combined
Cotton mouth combined

 

 

 

 

 

 

 

 

The pit vipers found in Arkansas include two members of the genus Agkistrodon, the cottonmouth (Agkistrodon piscivorous) and the copperhead (Agkistrodon contortrix). Occurring statewide, the cottonmouth (Agkistrodon piscivorous) is most commonly seen near water. It is one of the more aggressive of the venomous snakes found in Arkansas. The left photo shows the posture of an aggravated cottonmouth. The name "cottonmouth" refers to the light coloration of the mouth, which often is exposed as a warning (right photo). 

 

 

 

 

 

 The copperhead (Agkistrodon contortrix) occurs statewide and is most commonly seen in terrestrial habitats. Its coloration allows it to blend in very well with the leaves on the ground.

Copperhead
Pygmy

 

 

 

 

The other three species are rattlesnakes.

The pygmy or "ground" rattlesnake (Sistrurus miliarius) occurs statewide in Arkansas. Being a rattlesnake, it does have very small rattles at the tip of its tail. You cannot age a rattlesnake by counting the rattles because a new rattle is added each time the skin is shed.

 

Harmless snakes sometimes are feared to be rattlesnakes. In the right photo, a pygmy rattlesnake (left) lies beside a harmless hognose snake (Heterodon platirhinos). The hognose feeds primarily on toads and practically never bites a human. For images of the process of a hognose consuming a toad, click here.

Pygmy and hognose
Diamondback 2

 

 

 

 The diamondback rattlesnake (Crotalus atrox) is found in the southern Ouachita Mountains, Arkansas Valley, and in the southwestern Ozarks. This snake is sometimes called by the common name "coontail rattler" due to the black and white pattern on the tail.

The timber rattlesnake (Crotalus horridus) occurs statewide in a variety of habitats.

Although any of these snakes are capable of inflicting a dangerous bite, they really have no interest in biting a human unless they feel very threatened. In all these pit vipers, notice the coloration that helps them blend into their environment. To strike at a passing organism would reveal their location.

It has been argued that the rattle of the rattlesnakes is a secondary means of protection: if their camouflage has failed to protect them from being detected, the rattle can serve as a warning to avoid the need for defense through a bite. The venom is used to capture prey and biting a large organism would be a waste of their means of obtaining food. Thus, biting a human would be a last resort for a snake that feels extremely threatened. Using caution in outdoor activities is the easiest way to avoid a painfully negative encounter. 

Timber Rattler
 
 
 
 
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