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The Venom Chronicles: Venom FAQs

Part 1: Cobra Face-Off
Part 2: Box Jellies
Part 3: Super Spiders
Part 4: Dinosaur Venom
Part 5: Platypus Tales

In anticipation of the NOVA/National Geographic special Venom: Nature's Killer, premiering February 23 at 9pm on most PBS stations, Inside NOVA is bringing you The Venom Chronicles, a five-part blog series exploring fascinating venomous animals and the researchers who study them. We are very much looking forward to giving you the heebie-jeebies, the creepy-crawlies, and a sense of awe at what these amazing animals can do. But before we get started, let's take a moment to talk about some venom basics.

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Image Courtesy H Berends
What's the difference between venomous and poisonous animals?
Venom and poison are both substances that do harm, grouped under the umbrella term "toxin." The difference between them has to do with the delivery system. Poison must be eaten in order to be effective, as in the case of poisonous toads that injure or kill whatever tries to eat them. Venomous animals, on the other hand, usually have fangs or another related way of delivering the venom to their prey without needing to be eaten first. Of course, sometimes the two categories overlap. The yellow-bellied sea snake is a venomous animal with fangs that can cause serious damage if it bites you, but eating the venom can also be dangerous.

How does venom work?
Venom is made up of a combination of many different protein molecules that change the way your cells behave. The huge variety of toxins lead to many different effects on your body, depending on what kind of cells they target. An animal's venom may have one, some, or all of the following categories of toxins:
 
Neurotoxins affect the cells in your brain and nervous system. The most common effect is paralysis, but these molecules can also affect the way your brain cells communicate with each other.

Hemotoxins mostly target cells in your bloodstream, though they have impacts on other tissues as well. They can kill red blood cells, which deliver oxygen to the rest of your body, as well as disrupt normal blood clotting and cause organ failure.

Cytotoxins are responsible for spontaneous cell death in which a cell explodes and releases its fluid into the body. The tissue swells up and causes extraordinary pain.
How does antivenom work?
Antivenom is produced when a small amount of venom is injected into an animal, usually a horse, goat, sheep, or rabbit. The animal has an immune response to the venom and produces specialized antibodies: small proteins designed to counteract the effects of the toxic proteins in venom. Scientists can collect the antibodies from the animals and use them to treat people who have been bitten by a venomous animal. Because each type of venom produces a slightly different immune response and therefore a slightly different antibody, we only have a handful of antivenoms available for use on humans.

Isn't it "antivenin," not "antivenom"?
Excellent question! The term "antivenin" comes from the French word "venin," meaning venom. Though this usage used to be common, the World Health Organization decided in 1981 that "venom" and "antivenom" would be the preferred terms in English.

Why doesn't venom kill the venomous animal?
There are a couple reasons for this. First, venom is only effective if it makes it into the bloodstream. If a snake, for example, eats its own venom, the toxic proteins will be broken up in the stomach before they have a chance to do damage in the bloodstream. There is also evidence that snakes and other animals can make their own antivenomous proteins that circulate in their blood and neutralize any venom that makes its way through.

Will it kill me?
It all depends. Different cells are susceptible to damage by different toxins, so something that is lethal to an insect might have no effect on humans, and vice versa. Fortunately for us, the percentage of venomous animals out there that can kill humans is quite small--most of them are more interested in killing their prey, like fish or insects. But don't get too comfortable just yet. We'll be spending this week taking a closer look at some of the most dangerous venomous animals on the planet, and getting to know the brave researchers who learn about them.

Hannah Krakauer is a research intern at NOVA and a student at Stanford University.
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