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Is That Snake Venomous? - A Guide to the Key Characteristics of Venomous Snakes

Updated on January 3, 2015

Is It Safe?

Many people are afraid of snakes, because they don't want to be bitten by a venomous snake. Most snakes, however, are not venomous. In fact, there are only 400 known species of venomous snakes around the world out of a total of approximately 2900 snake species. The majority of those 400 venomous snakes are located in tropical regions and not native to the northern hemisphere. Approximately 80% of all snakes you might encounter, anywhere in the world (with the exception of Australia where this statistic is reversed) are non-venomous. Chances are, if you see a snake, it is perfectly harmless.

Common Garter Snake

The most common snake species of North America (non-venomous).
The most common snake species of North America (non-venomous).

Key Features

Snakes that are venomous generally follow certain "rules" with regard to their physical characteristics, making it easy to tell the difference between a snake that is venomous and a snake that is not. These key identifying features include their-

  • Eyes
  • Scale Texture
  • Head Shape
  • Teeth and
  • Body Morphology

With practice, you should be able to recognize the differences from a distance and have no problem avoiding contact with dangerous venomous snakes.

Green Tree Python

A non-venomous snake native to South America - this snake mimics many of the venomous characteristics discussed in this article.
A non-venomous snake native to South America - this snake mimics many of the venomous characteristics discussed in this article.

The Eyes

In most venomous snake species, the eyes are large with a vertical pupil slit, much like the eye of a cat. This is different from the rounded pupil of most non-venomous snakes.

Green Bush Viper

A venomous snake native to the forests of West Africa from Guinea to Gabon.
A venomous snake native to the forests of West Africa from Guinea to Gabon.

Scale Texture

Most snakes appear very smooth to the touch, giving them a reputation as "slimy". However, the scales of a venomous snake appear rough and bumpy, almost like sandpaper.

Saharan Horned Viper

A venomous snake native to the deserts of Northern Africa.
A venomous snake native to the deserts of Northern Africa.

Head Shape

Many species of venomous snakes have a distinctive triangular shape to their head, thanks to the enlarged jaw muscles just behind the eyes. This allows the extra room for their poison sacs that would not be found in a non-venomous snake.

Timber Rattlesnake

This venomous snake is native to the temperate forests of North America.
This venomous snake is native to the temperate forests of North America.

Teeth

Venomous snakes can be equipped with either front folding fangs or smaller rear fangs. Most, have the very obvious front fangs, and non-venomous snakes have no fangs at all. If bitten by a non-venomous snake, the bite wound will appear circular, while a bite from a venomous snake will sport two punctures from the fangs.

Cottonmouth or Water Moccasin

A venomous snake native to the southern range of North America, frequenting stream beds and riverbanks.
A venomous snake native to the southern range of North America, frequenting stream beds and riverbanks.

Body Morphology

Non-venomous snakes tend to have smooth "straight" bodies, while a venomous snake will typically appear thick and wide.

Sidewinder or Horned Rattlesnake

A venomous snake native to northern Mexico and the southern United States.
A venomous snake native to northern Mexico and the southern United States.

Rule Breakers

As is the case with any rule, there are exceptions. Snakes, however, like to advertise that they are dangerous as this encourages potential predators to stay away. Even those snakes who break the rules of venomous identification have easily identifiable markers that make them stand out.

Cobras, for example, break most of the rules with round pupils, smooth thin bodies and a standard non-triangular snake head. However, these species can be easily spotted thanks to the flaps of skin on their necks that fan out when a cobra feels threatened.

Indian Cobra

Venomous snake species native to eastern India.
Venomous snake species native to eastern India.

The Coral Snake

A coral snake is one of those unique rule breakers who sports none of the identifying characteristics of a venomous sake. There is, however, a rhyme which makes it easy to spot when compared to the non-venomous king snake which mimics its coloring.

"Red on yellow kills a fellow; red on black, you're okay Jack!"

The Coral Snake

A venomous snake that doesn't even sport fangs - watch for the characteristic color pattern with red stripes touching yellow.
A venomous snake that doesn't even sport fangs - watch for the characteristic color pattern with red stripes touching yellow.

Additional Features

Most of the venomous snakes in North America sport a couple "extra" identifiable characteristics. These are all snakes known as "pit vipers", because they have additional holes near their nasal passages which aid in the detection of heat, making it easier for them to seek out prey. Several of the species in the pit viper family are rattle snakes and also sport the obvious rattle at the end of their tail.

Gumprecht's Green Pit Viper

This venomous snake is native to Southeast Asia.
This venomous snake is native to Southeast Asia.

Testing Your Knowledge in the Field

If you are a snake aficionado, exercise caution in the field. While these characteristics are a great help in making a cursory "at a glance" judgment call, one should always become familiar with the exact identification of all venomous species native to your area before attempting to pick up any wild snakes.

Venomous snakes should only be handled by professionals. Should you stumble on one and find yourself bitten - keep the snake with you, if possible, so that doctors can ensure it was properly identified and you can be given the correct anti-venom.

Remember to look for the puncture wounds, characteristic of fangs only sported by venomous species, remain as still as possible, tie a tourniquet and call an ambulance. Always exercise caution when interacting with wildlife, for your own safety and the safety of the animal in question.

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