Venom Vs. Poison

Venomous snakes have a bad reputation world wide, the fact is that only 20% of the snakes on earth are venomous. This leaves approximately 80% who hunt using something other than venom to subdue their prey. Snake venom is a cocktail of proteins that perform a wide range of functions. 

There are basically three different kinds of snake venom.

Hemotoxic venoms act on the heart and cardiovascular system.
Neurotoxic venom acts on the nervous system and brain.
Cytotoxic venom has a localized action at the site of the bite.
Some snakes combine venom types for a more effective bite, while others only carry one specific form of venom. All venoms contain a complex cocktail of proteins and enzymes.


Gila Monster / Heloderma Horned Adder / Bitis caudalis
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Photo by: J.L. Gingerich D.V.M.

Photo by: J.L. Gingerich D.V.M.

Some snakes are hemotoxic, meaning they break down blood cells and cause extreme coagulation of their victims blood. Other snakes are neurotoxic, a neurotoxic snake uses a powerful venom to block the messages the nerves are trying to send to the muscles, this generally leads to prey items suffocating as the central nervous system shuts down and prevents the animals lungs from functioning.

Hemotoxins, haemotoxins or hematotoxins are toxins that destroy red blood cells (that is, cause hemolysis), disrupt blood clotting, and/or cause organ degeneration and generalized tissue damage. The term hemotoxin is to some degree a misnomer since toxins that damage the blood also damage other tissues. Injury from a hemotoxic agent is often very painful and can cause permanent damage. Loss of an affected limb is possible even with prompt treatment. Hemotoxins are frequently employed by venomous animals, including pit vipers. Animal venoms contain enzymes and other proteins that are hemotoxic or neurotoxic or occasionally both (as in the Mojave Rattlesnake and similar species). In addition to killing the prey, part of the function of a hemotoxic venom for some animals is to aid digestion. The venom breaks down protein in the region of the bite, making prey easier to digest. The process by which a hemotoxin causes death is much slower than that of a neurotoxin. Snakes which envenomate a prey animal may have to track the prey as it flees. Typically, a mammalian prey item will stop fleeing not because of death, but due to shock caused by the venomous bite. Dependent upon species, size, location of bite and the amount of venom injected, symptoms in humans such as nausea, disorientation, and headache may be delayed for several hours.

Many of the venoms and other toxins that organisms use in defense against vertebrates are neurotoxins. A common effect is paralysis, which sets in very rapidly. The venom of bees, scorpions, pufferfish, spiders and snakes can contain many different toxins.

When someone is bitten by a snake with hemotoxic venom, the venom typically acts to lower blood pressure causing bite victims to experience large amounts of blood loss. The venom may also attack the heart muscle with the goal of causing death. Cytotoxic venom is designed to cause tissue death, which is why some people have to receive amputations after being bitten, because the venom has eaten away the localized tissue. Many cytotoxic venoms can also spread through the body, increasing muscle permeability so that the venom can penetrate quickly.

A neurotoxic venom works to disrupt the function of the brain and nervous system. Classically, such snake venom causes paralysis or lack of muscle control, but it can also disrupt the individual signals sent between neurons and muscles.

C. atrox Although the venom of the diamondback isn't particularly toxic, the size of the snake allows a larger capacity of venom which is released from its two prominent fangs. It's not uncommon that only one bite mark from one fang is visible after a strike. Fangs can break or bend, or the bite area may be small, causing a miss. All pit vipers have the ability to control the flow of venom through their fangs, allowing the diamondback to release most of its venom in a single strike (though often a pit viper will not release any of its venom).

Most of the toxin released is proteolytic like all other American pit vipers. Proteolytic venoms are, in fact, advanced and concentrated fluids that destroy tissues and other cells through intramolecular digestion. A few toxic effects include: cytotoxic (destroys cells), hemotoxic (destroys red blood cells), myotoxic (causes paralysis and muscle destruction), hemorrhagic (causes persistent bleeding). Smaller amounts of neurotoxins are also present. Unlike neurotoxins, hemotoxin envenomations becomes quickly apparent; the area around the wound swells at a rapid rate. Discoloration and pain are also experienced shortly after being bitten. Professional medical attention should be sought immediately, especially when the victim is a child. The smaller the victim the less time it takes for the venom to spread. Although it is commonly believed that baby or young rattlesnakes deliver more concentrated venom and are thus more dangerous, this idea is not supported by scientific evidence. The amount of venom delivered is a much more important indicator of the bite's danger than the venom's concentration, and since larger (older) snakes can deliver much more venom, larger rattlesnakes should always be considered more dangerous even though many bites from adult snakes are "dry".

Habu / Trimeresurus Black Widow
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What is the difference between poison and venom?
If you drink venom, will it kill you?

Poisons are substances that are toxic (cause harm) if swallowed or inhaled. Venoms are generally not toxic if swallowed, and must be injected under the skin (by snakes, spiders, etc.) into the tissues normally protected by skin in order to be toxic.

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Photo by: J.L. Gingerich D.V.M.

Photo by: J.L. Gingerich D.V.M.

Venomous vs. poisonous
There is a difference between organisms that are venomous and those that are poisonous, two commonly confused terms applied to plant and animal life. Venomous, as stated above, refers to animals that deliver (often, inject) venom into their prey when hunting or as a defense mechanism. Poisonous, on the other hand, describes plants or animals that are harmful when consumed or touched. A poison tends to be distributed over a large part of the body of the organism producing it, while venom is typically produced in organs specialized for the purpose. One species of bird, the hooded pitohui, although not venomous, is poisonous, secreting a neurotoxin onto its skin and feathers. The slow loris, a primate, blurs the boundary between poisonous and venomous. From patches on the inside of its elbows it secretes a toxin, which it is believed to smear on its young to prevent them from being eaten; however, it will also lick these patches, giving it a venomous bite.

Snakes are not poisonous and frogs are not venomous. Venom is a toxic substance that is injected. Certain species of snakes, scorpions and spiders are venomous, not poisonous. Venom glands typically form the toxic substance and the venom is stored until it is needed. The venomous animal will then bite or sting another creature, whether as intended prey or in defense, and the venom will be injected. Depending on the amount injected, the susceptibility of the animal injected and the size of the animal, various degrees of illness, including death, can occur. 
If you call a snake poisonous, you are actually implying that the snake has a toxic substance on his body and poisoning will occur if the snake is handled. This does not occur. Venom is used primarily to immobilize prey and is rarely used as a defense mechanism. The venomous animal will bite in an attack but injecting venom is usually reserved for prey items.

A poison is a substance that is absorbed through the skin or ingested, resulting in toxicity. Certain amphibians, fish and insects secrete a substance that is poisonous. The poisonous animal does not inject the substance into another creature. The substance is either absorbed through the skin or ingested when the poisonous animal is placed in the mouth or swallowed. Poison is typically used as a defense mechanism and is rarely used to incapacitate prey.

Death Adder / Acanthophis

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Photo by: J.L. Gingerich D.V.M.

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