How To Tell If A Snake Is Venomous

A blue viper on a branch.

People’s dread of snakes seems like a primordial one. Snakes are hard to spot; they are very fast in movement. They can slither into almost anything and climb anywhere. Some snakes are venomous, which makes them threatening for any species which are vulnerable to their venom. We as humans should be cautious when we found ourselves eye to eye with a snake, and here are some characteristics that may help you recognize a venomous snake but there are exceptions.

Eye Shape

First of all, if you see a snake whose eyes resemble a cat’s eye, it is almost sure that it is venomous. A venomous snake has pupils that are ellipse-shaped. So, if you ever see slit-like eyes staring at you, definitely move away slowly! There are however snakes like the coral snake that does have round eyes and inland taipan one of the most dangerous snakes can have a different eye shape depending on the type of day. 

Head Shape

The head of a venomous snake is in the shape of a triangle, and it is pretty wide, in proportion to the width of the snake’s body. Most of the snake’s heads are broader than their bodies, but when a snake is venomous, it is pronounced, because of the venom sacks it holds. They are under the snake’s jaw, which creates a bulge that is hard to miss. However, there are still plenty of skinny headed snakes that keep their venom elsewhere.

Body Patterns

Venomous snakes are pretty, and they develop multi-colored and vibrant patterns across their skin, which makes them very recognizable. The more vivid the colors, the more careful you should be. Unfortunately, there are some exceptions, like the one we see in the species called the Black Mamba (Dendroaspis polylepis). The Black Mamba is not even black, it comes in straightforward shades of grey and brown, but is one of the deadliest snakes on Earth. 

Tail Rattle

This one is a dead giveaway. If you hear rattling, you should be very careful. All of the snakes make a rattle-like sound when they move, but the rattlesnake sound is very distinctive. The tail of a rattlesnake sounds like a ‘’shaker’’, and rapid contractions make a noise of its scales located on the very end of the snake’s tail. Those contractions happen with an impressive speed of 50 Hz (50 times a second). 

Heat-Sensing Pit

One of the traits that you do not want to inspect on your own when you suspect a snake is venomous. All venomous vipers have a small pit located between the eyes and the nose, which serves as a heat detector and helps them hunt prey. However inland taipan and its subfamily Elapidae all don't have facial pits. 


You can easily distinguish venomous from non-venomous snakes by the way they act when in water. If you see only the head of a snake sticking out of the water, it is most likely completely harmless. On the other hand, all venomous snakes float on the surface of the water, with their whole body being visible that way. 


If you ever get bitten by a non-venomous snake, it will leave a circular mark as it breaks your skin. Venomous snakes, however, have very prominent front fangs, and they will puncture the skin, leaving two small dotted spots. 

With all these characteristics described, you should be able to distinguish some venomous from non-venomous snakes. However, you should always consult an expert to verify.  If you get bit always go to the hospital and make sure if possible to get a picture of the snake. As in nature, there are always exceptions, and your best bet is to get away immediately and call animal control to take care of the case. 

One of the biggest deceivers is the coral snake, which practically does not follow any of these attributes. The coral snakes of North America do not have a triangle-shaped head, heat-sensors, or elliptical pupils. However, a flashy red-yellow combination of colors on a black body means - stay away!


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