Venoms and Poisons - What is the Difference?
Dr. Dawn Ruben
Eating and surviving are two of the strongest urges in any animal. Except during breeding season, the instincts to eat and live are the primary driving life forces. Reptiles and amphibians have developed a variety of ways to capture prey and keep predators at bay.
Two popular methods involve venom and poison. These may sound like the same thing, but they are actually quite different. Repiles and amphibians use one or the other to help immobilize prey and/or to keep from being someone else's dinner.
Who's for Dinner Tonight
Many reptiles ambush their prey by finding a tasty looking creature and simply grabbing and swallowing. Others have a more refined way: they immobilize prey to make eating easier. (Immobilizing is a lot better than risking injury while dining.) Some reptiles constrict and suffocate their prey. Others have special glands that produce a toxic substance that is injected into the potential prey when bitten. Even some members of the invertebrate world, like spiders and scorpions, have developed methods to immobilize their prey through the use of bites or stingers.
The other important instinct in animals is to avoid being eaten. Many reptiles and amphibians are prey items for other creatures. Some are able to secrete distasteful or even harmful substances that will prevent the predator from eating them. Once the predator has the animal in his mouth, and begins to taste the bitter, toxic flavor, he will spit the animal out.
These are well known survival techniques employed by various animals but what is the proper term used to describe the substances produced by animals? Is it venom or poison?
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.
The Komodo dragon is thought by many people to be a poisonous reptile. Some even think it is venomous. Neither is correct. The Komodo dragon does not produce any poisonous or venomous substance. The dragon has a large population of deadly bacteria living in his mouth. He will bite a potential prey victim, causing bacterial contamination of the bite wound. The animal's immune system is unable to fight off the bacteria and, over the course of a few days, the animal slowly succumbs as the infection spreads through the body. During this time, the Komodo dragon will follow and stalk his prey until the animal collapses and is near death from sepsis.
At this point, the Komodo dragon begins his dinner. The bacteria in the mouth of the Komodo dragon is so deadly that there are no antibiotics currently available to treat an established infection. Bites from the Komodo dragon usually result in death, despite aggressive medical care.