Difference between Venomous and Non-venomous Snakes

Updated on August 8, 2016

If you see a snake in your backyard or elsewhere near the place you live, the best advice is not to look for telltale signs of a venomous snake, but just leave it alone, and call the animal control service responsible for handling snakes in your area. For other purposes, we will discuss the differences between the two types of snakes in this article.


Venomous snakes

Most snakes are what are commonly referred to as clinically non-venomous. Non-venomous snakes have teeth and they bite just like venomous snakes. Even though there is no venom injected as a result of a bite, medical care should be sought because any snake carries a number of infections. A bite from a large snake, such as a python, can result in massive injuries and it is advisable to take care of the wound  immediately. Many snakes that carry toxins are not dangerous for a human being. These include Hognose snakes, Garter snakes and Rat snakes, to name a few.

There are “genuinely” non-venomous snakes, such as pythons, bull snakes, boas and king snakes.

High-Yellow Sorong Amethystine Scrub Python
A High-Yellow Sorong Amethystine Scrub Python, a truly non-venomous snake

Venomous snakes are species that produce venom, a poison which works as an immobilizing weapon  used by snakes as a defense or when they hunt prey. The venom is injected via their fangs.

In toxicology, there is a term “median lethal dose” which refers to the amount of venom that needs to be injected into the living organism, such as the human organism, in order for it to die. The toxicity of a particular species of snakes is indicated by its median lethal dose, while there are a variety of factors one should take into consideration to consider the actual level of danger of a particular venomous snake.

Among 2600 different species of snakes, there are around 400 venomous snakes, while the rest are non-venomous. In the United States alone, there are roughly 130 species of snakes, and of those, 21 are venomous.

In the United States, there are four dominant families of venomous snakes that include the lapidae, also known as coral snakes. Coral snakes live mainly in the state of Florida. This is the most venomous snake in the United States.

A venomous coral snake
A venomous coral snake

The other three common families of snakes in the U.S. include copperheads, rattlesnakes and cottonmouths snakes.

Comparison chart

Venomous snakesNon-venomous snakes
Usually have a triangular-shaped or diamond-shaped headUsually have a rounded head
During the daytime, pupils look like slitsPupils are circular
A single row of scales at the end of the tailA visible line separates two rows of scales at the end of the tail
Have a heat sensing pit on the headOften do not have a heat sensing pit on the head

Venomous snakes vs Non-venomous snakes

What is the difference between venomous snakes and non-venomous snakes?

  • Due to the venom gland, the head of a venomous snake is shaped triangularly. Sometimes it can take a diamond-like form. The head of a non-venomous snake, on the other hand, has a rounded shape. However, some non-venomous snakes, mainly water snakes, when they become aggressive, spread their body in order to look more threatening to an enemy or a prey, and their head starts to look triangular because their jaws protrude outward.
Eastern green mamba
Eastern green mamba
  • The eyes of a venomous snake look like cat’s eyes, with pupils like vertical slits. Non-venomous snakes, on the other hand, have circular eyes, somewhat similar to human eyes. Eyes, however, cannot always be a full-proof telltale sign of a venomous/ non-venomous snake. In the summer season, in the United States, most venomous snakes become nocturnal, and their eyes change to the nocturnal variation. That is, they look like circular eyes because pupils need to be adjusted by the visual system of a snake in order to see things properly.
Asian vine snake
Asian vine snake with slit-like eyes
  • Contrary to popular belief, all snakes have tails. That is, the head is a separate organ from the tail. The tail of non- venomous snakes has a double row of scales on the end of the tail (from the anus to the very end.) There is a visible line that separates the two rows. Venomous snakes, on the other hand, have a single row of scales on the end of the tail. If you do not see the line separating two rows of scales, this is a telltale sign that a snake is poisonous.
If the underside of a snake has a single row of scales, the snake is most probably venomous. Likewise, if the tail plates are in double plates, the snake is likely to be non-venomous.
If the underside of a snake has a single row of scales, the snake is most probably venomous. Likewise, if the tail plates are in double plates, the snake is likely to be non-venomous.
  • Venomous snakes have heat sensing pits that work like a heat detector to identify the whereabouts of a prey. Heat sensing tips are situated between the eye and the nostril of the snake. Some non-venomous snakes also have a heat sensing pit, but most do not.
Heat sensing pits are telltale signs of a venomous snake.
Heat sensing pits are telltale signs of a venomous snake.


In this video you can see the guide on the basic differences between venomous and non-venomous snakes:

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