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The Science Behind Venomous Snake Bites

by Globetrooper Todd | 8 Responses
Science of Venomous Snake Bites

Snakes primarily use their venom to debilitate and digest prey. Sure, humans aren’t prey for most venomous snakes, but the toxins work on us in the same way. I mention this because if you keep in mind that venom is intended to secure food, its excessive effects make much more sense.

Like my previous post about the effects of drinking sea water, I’m taking a bit of a gamble that you’ll find this topic as interesting as I do.

Types of Snake Venom

Before we get into the juicy details, let’s look at the three types of toxins in snake venom:

  1. Hemotoxic venom affects the heart and cardiovascular system
  2. Neurotoxic venom affects the nervous system and brain
  3. Cytotoxic venom has a localised effect on the bite area

Snakes can deliver a combination of these venoms to capture, debilitate, kill and digest prey. Unfortunately for humans, many snakes are blessed with venom that is far in excess of day-to-day needs. For example, the venom in a single bite of the non-agressive Inland Taipan has the potency to kill 250,000 mice. Scientists are still unsure why snake venom has evolved to such extremes.

Types of Venomous Snakes

There are three families of venomous snake. Each family has a unique venom delivery method, so it’s best to think about the science of venomous bites on a per-family basis.

1. Elapidae – The Most Deadly

Species: Taipan, Tiger, Cobra, Mamba, Brown, Coral, Sea Snake (Hydrophiidae) and more.

Black Mamba

A Black Mamba - Discovering Tanzania

Fangs: Hollow (like a hypodermic needle) and fixed (they cannot be folded), but typically short. Due to the short size, the snake will hold on longer to ensure envenomation. Snakes risk injury when they hold on, but the potency of elapid venom ensures the victim is paralysed quickly.

Venom: Predominantly fast-acting neurotoxins, which rapidly cause paralysis of muscles.

Effect: Many bites from elapids are painless, which is a worry because the elapidae family is the most deadly. The fast-acting neurotoxins can paralyse the respiratory system in hours and lead to numbness, nausea, dizziness and death.

2. Viperidae – The Most Painful

Species: Viper, Rattlesnake, Adder, Bushmaster, Copperhead and more.

Waglers Pit Viper

Waglers Pit Viper in Malaysia - NeilsPhotography

Fangs: Long, hollow and hinged (they extend and fold as the mouth opens and closes). This is the most efficient delivery method because the folding mechanism allows for much longer fangs that penetrate deeper. However, viperid venom isn’t typically as potent as elapid venom, but can be just as deadly since it’s injected much deeper with the long fangs.

Venom: Hemotoxins and cytotoxins, which attack the blood and destroy tissue.

Effect: Most bites are very painful because the cytotoxins destroy tissue immediately. This sometimes requires the amputation of a limb. The hemotoxins, especially in large doses, can be deadly as they cause internal bleeding, excessive blood clotting and organ failure. Bites may be dry, i.e. without venom.

3. Colubridae – The Least Harmful

Species: Boomslang, Rat Snake, Vine Snake and about two thirds of all snake species.

Boomslang

Close up of a Boomslang Snake in Tanzania - wwarby

Fangs: Rear-grooved, not hollow, which means the venom drips along the grooves into the victim. This is much less efficient as a delivery system, but some colubrids can kill.

Venom: All toxins, depending on sub-family.

Humans: Most bites aren’t harmful or deadly to humans, though there have been a few fatal cases from Boomslangs.

Types of Venom Injection

The deadliness of a snake bite depends on where the venom is injected. A snake with less potent venom can be much more deadly than one with more potent venom if it injects the venom directly into your blood stream (opposed to just your skin or muscles).

  • Subcutaneous – into the skin, which is most likely
  • Intramuscular - directly into the muscle, which is less likely
  • Intravenous - directly into the blood stream, which is very rare in reality

The World’s Most Venomous Snakes

Any discussion about ‘the most venomous snakes’ is purely academic because we can’t test snake venom on a large enough sample of humans (for obvious reasons). So most lists you see on the Internet are based on tests with mice, even though they can have different reactions to humans. According to these mice tests, the most venomous snakes are as follows:

  1. Inland Taipan – found in Australia
  2. Eastern Brown Snake – found in Australia
  3. Coastal Taipan – found in Australia and New Guinea
  4. Tiger Snake – found in Australia
  5. Beaked Sea Snake – found in Australia
Inland Taipan

An Inland Taipan, the most venomous snake - Haddi Paddi & Adda Padda

Of course, these snakes aren’t necessarily the most deadly. But then any discussion about the deadliness of snakes is also highly subjective. Is it the snake with the most potent venom, the most global fatalities, the highest bite to kill ratio, or the most aggressive nature? There’s no real answer, so let’s look at all of these:

  • Most Potent Venom (land): Inland Taipan, found in Australia
  • Most Global Fatalities: Indian Cobra and Russel’s Viper, most fatalities in India
  • Highest Bite-to-Kill ratio: Coastal Taipan, found in Australia
  • Most Aggressive: Black Mamba, Russel’s Viper, Eastern Brown Snake

What About Anti-Venom?

Anti-venom is created by injecting horses, sheep, goats or rabbits with small (non-lethal) quantities of venom to effect an immune response. Scientists can then harvest the necessary antibodies from the injected animal to produce anti-venom for humans.

Some anti-venoms are polyvalent, meaning they can act against the venom of many species, but some snake bites require a monovalent, or specialist, anti-venom. Even though Australia has most of the worlds top 10 most venomous snakes, the availability of anti-venom means Australia has one of the lowest death tolls from snake bites.

Featured photo is a Corn Snake by goingslo

Posted in Adventure Travel, Featured | September 27th, 2010

8 Responses to The Science Behind Venomous Snake Bites

  1. Horrible! I live in Australia, have a severe disike for snakes, and apparantly need to deal with the most deadly of them!
    Daniel

    • You’ll be glad to know there hasn’t been a recorded death in Australia from a spider bite since 1979. Can’t say the same for snakes. :)

  2. Great post! I stepped over a krait two months ago in Lambir Hills National Park, Borneo. I didn’t see the little thing but realized later that they are extremely venomous. Any idea what class they fall in?

    • Hey Greg, wow you’re quite lucky, the kraits (including the Common Krait) belong to the Elapidae family, and like you said, are highly highly venomous with a nasty neurotoxin. In general, they’re much more venomous than cobras. They’re responsible for thousands of deaths per year. Should I keep going? :) The scary part is that the bite is relatively painless. It gets better. The antivenin is often not polyvalent; so unless you correctly identify the exact species of krait, the antivenin is, well, useless. The consolation is that they’re nocturnal and relatively placid during the day, unless you step on them of course.

      You know, it seems to come down to how remote you are and how effective antivenin is. Sure we have the most venomous snakes in the world in Australia, but generally antivenin is close at hand and quite effective. Some of the slightly less venomous snakes are that much dangerous because they’re encountered far from assistance and the antivenin is not so reliable.

      We just spent 10 days in the Peruvian jungle and while we didn’t come across quite as venomous snakes, just the thought of being so far from help is really daunting.

  3. Yikes! The only reason I saw the little guy on the trail is because it had a brightly colored tail. Thanks for the info, going to retweet.

  4. My friend and I have a bet. Which venomous snake kills the fastest with the least pain?
    Thanks!

  5. It helps when you have an understanding of these snakes, they’re not just there to bite in an instant, still I froze when I saw one during a hiking trip back in college.

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