How to tell if a snake is venomous

Out of 3,971 snake species in the world today, only 600 are venomous. To make this number even smaller, only 200 species around the world are considered potentially dangerous to humans and most of our animals companions.

The suborder Serpentes is divided into two infraorders, the smaller group, Scolecophidia, describes 5 families of snakes, with species such as blind snakes. Many are fossorial (live underground) and therefore aren’t often seen. The other group, Alethinophidia, is the larger infraorder, with 25 families.

There are five families in the infraorder Alethinophidia that you should know:

1. Elapidae: These are some of the most venomous snakes, like Cobras (Naja), Mambas (Dendroaspis), and the Inland Taipan (Oxyuranus microlepidotus), considered the most venomous snake in the world. Elapids closely resemble the colubrid family.
2. Colubridae: These snakes are generally non-venomous or mildly venomous, and are the most common around the world. A few common species within the family are Rat Snakes (Pantherophis), Water Snakes (Nerodia), Racers (Coluber), and Garter Snakes (Thamnophis).
3. Viperdae: A grouping of snakes that are usually shorter and wider with long venomous fangs. These include Rattlesnakes (Crotalus), Bush Vipers (Atheris) and Copperheads (Agkistrodon) to name a few.
4. Boidae: Often smaller than their similar family Pythonidae, with the exception of the Green Anaconda (Eunectes murinus), which is considered the largest and certainly heaviest extant snake in the world. The biggest difference between boas and pythons is their way of reproduction. I will be doing a post about this soon.
5. Pythonidae: A group of often large constrictor snakes such as the Burmese Python (Python bivittatus), Reticulated Python (Malayopython reticulatus), and Ball Python (Python regius).

Snake venom is modified saliva, and the toxicity falls into more of a range than a strict formula. Similar to bee stings, the reaction can vary from person to person. With snake species in the Elapid and Viper family, the reaction to venom is almost always severe and should be medically treated.

However, some colubrid snakes, like hognose snakes and even tiny ringneck snakes, are also considered venomous. Their venom is mild enough that it is not harmful to humans, and they have small Opisthoglyphous fangs in the rear of their mouths versus the front, meaning an actual envenomation is unlikely. I have actually experienced an envenomation from my Western Hognose Snake (Heterodon nasicus), and can say that the venom is very mild. To read more about the interesting behaviors of genus Heterodon (hognose snakes), you can click here.

Remember if a snake is hiding, it will not emerge from its hiding place to bite a passing human that would put the snake in unnecessary harm. The only time a snake will attempt to harm a human is if it feels there is no other option, so as long as you do not step on or grab a snake, you (and the snake) will be safe.

Snakes are an important part of the ecosystem; they are both predator to mostly rodents and amphibians, and prey to large birds and sometimes other snakes. And still, some people aren’t as excited to have snakes in their yard.

If you have a venomous snake in your yard, that means you are living on land that is suitable for snakes (hooray!), which means snakes will go and live there.

By killing or attempting to kill a venomous snake in your yard, you are putting yourself in unnecessary harm given that so many snake bites come when trying to kill a snake (obviously, the snake is desperately trying to save its life)!

If your yard is a good place for snakes, more will likely show up anyway. This is not to say that you should just stay safe inside, but rather be aware that there are always going to be other creatures all around you, and the best thing you can do to keep your yard free from snakes is to make sure there aren’t many places for them to hide. Things such as fallen limbs, tires, metal roofing, and hoses are all prime areas for a snake to be found. There are also lots of people around the world excited to help relocate snakes and share their passion (including me).

It is impossible to identify all venomous snakes based on the same visual cues. Instead, you can learn to identify the different families of snakes and know which families are venomous. In North America this can be pretty easy; with the exception of copperhead and water moccasin species (both from the genus Agkistrodon), just about every viper species here has a rattle. They also have loreal or heat sensing pits between their eyes and nostrils. They also have a bulky body and large head. The only Elapid snakes in North America are the coral snakes. They have stripes and the yellow and red bands are touching.

But the colubrids (mild or non-venomous) are good actors and may mimic the colors and shapes of venomous snakes. For example, many colubrid snakes will spread out their flexible jaws to look like a venomous viper snake. And just about any snake you’ll come across will rattle its tail. Only rattlesnakes have true rattles, but all snakes may shake their tails when they feel threatened. This is not actually to mimic the venomous rattlesnakes, but it may have evolved simultaneously and even prier to the rattle snakes adaptation, you can learn more about snake rattles here.

There are rule breakers for every trick you may have heard, so the best way I have found is to pay attention to the whole animal rather than focusing on specific parts (like looking for the loreal pit in a rattlesnake or the bands in a coral snake). More often I’m paying attention to the head and body shape, as well as the body language and way of movement, because the pattern and color often varies between individuals within a species.

So here is a quiz that you can retake as much as you want that can help you become familiar with some of the common species you may see around North America. Go through it slowly and really pay attention to the images so that you can get to know the snake species. You can take it as many times as you want, and when you get the right answer I share where I found the snake as well.

Snakes are fascinating creatures, and, just like dogs, it’s important to respect their strength and their space, and pay attention to the body language. The more you know, the less there is to be fearful about.

Sources: NationalGeographic, Wikipedia, personal experience