Venom Types Methods of Production Methods of Delivery Offense or Defense? Lethal injection or False alarm? Mysteries Warnings
To most people venom and snakes go hand in hand. It is commonly believed that all snakes are venomous, but this is an erroneous belief. Of the 2.700 known species of snake only 300 are venomous. So what is venom, how did snakes get it and why do they have it? These are questions that have interested herpetologists and other scientists alike.
Venom itself is a poison secreted by animals for either defensive or offensive purposes. Venom originated from digestive enzymes that were originally located in the stomach. Throughout the millions of years it has progressed quite a lot and in some animals has become quite different from it's origin. The type of venom depends on the type of animal. In spiders venom is kept rather simple. It is pretty much just digestive enzymes. Spiders use their venom to turn their hard shelled insect meals into nice and nutritious goo. So in a sense one can think of this type of venom as a form of starting the digestive process before you even start to eat the meal.
In insects venom is used predominantly as a defensive weapon. Wasps, bees and ants use formic acid in their stings to cause a painful burning sensation that will either kill or injure their enemy enough to make them think twice about attacking them again. Amphibians all use their venom for defense. In amphibians the venom is secreted through glands in the skin to make the animals unpalatable.
So as we can see venom is a predominantly defensive adaptation. An adaptation that has found it's way into every class of vertebrates except one. The birds; the only class to forego any venom. In mammals we have platypi with venomous claws, then there are the fish which comprise too many venomous species to count and finally we have the reptiles.
All venomous reptiles are squamates and of them snakes make up the bulk. There are only two species of venomous squamates that are not snakes, the lizards of the genus: Heloderma. These lizards use their venom for defense as well and can deliver powerful and painful bites. In snakes venom has found a new use, for offense. Since snake prey generally has the advantage of speed (not to say that snakes can't be speedy. A black mamba traveling at 17 mph is nothing to sneeze at.) snakes had to find a new way to take down their prey without running the risk of losing them or getting too hurt in the process. Enter venom, a fast and effective mode of subdueing prey items with minimal risk to the snake.
Snake venom can be divided into two broad (yet fuzzy) categories. That of hemotoxicity and neurotoxicity. Hemotoxic venom effects the blood and organs, causing a breakdown or inflammation in the body. Hemotoxic bites are the most painful as breathing hurts and tissues start to die.
Neurotoxic venom, as the name suggests, effect the nervous system, leading to everything from siezures to death. Neurotoxic bites are the most deadly. Although we have these two wonderful different categories, no snake fits completely in each. Many snakes incorporate both neurotoxic and hemotoxic venom in their bites so when telling them apart one goes by which type is more predominant.
For instance Ophiophagous hannah (King Cobra) has predominantly neurotoxic venom while Crotalus adamanteus (Eastern diamondback rattlesnake) has predominantly hemotoxic venom. Methods of production
While getting bitten by a snake might strike fear in people, the fangs are not where the venom comes from, they are mearly methods of transfer. The place where the venom is made is in special glands located on the head of the animal. The venom glands differentiate into false and true venom glands. False venom glands (a misleading name no doubt) are made up either from mucus producing supralabial glands that run on either side of the head extending as a continuous strip from near the snout to...