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Thursday, September 2, 2010

Snake Talk

Venomous Snakes and Lizards:

If you fear snakes, it is probably because you are unfamiliar with them or you have wrong information about them. There is no need for you to fear snakes if you know:

• Their habits.
• How to identify the dangerous kinds
• Precautions to take to prevent snakebite.
• What actions to take in case of snakebite.

For a man wearing shoes and trousers and living in a camp, the danger of being bitten by a venomous snake is small compared to the hazards of malaria, cholera, dysentery, or other diseases.

Nearly all snakes avoid man if possible. A few—the king cobra of Southeast Asia, the bushmaster and tropical rattlesnake of South America, and the mamba of Africa—may aggressively attack man, but even these snakes do so only occasionally. Most snakes get out of the way and are seldom seen.


1. Snakes are widely distributed. They are found in all tropical, subtropical, and most temperate regions. Some species of snakes have specialized glands that contain a toxic venom, and long, hollow fangs to inject their venom.

2. Although venomous snakes use their venom to secure food, they also use it for self-defense. Human accidents occur when you don't see or hear the snake, when you step on them, or when you walk too close to them.

3. Follow these simple rules to reduce the chance of accidental snakebite:

• Don't sleep next to brush, tall grass, large boulders, or trees. They provide hiding places for snakes. Place your sleeping bag in a clearing. Use mosquito netting tucked well under the bag. This netting should provide a good barrier.

• Don't put your hands into dark places, such as rock crevices, heavy brush, or hollow logs, without first investigating.

• Don't step over a fallen tree. Step on the log and look to see if there is a snake resting on the other side.

• Don't walk through heavy brush or tall grass without looking down. Look where you are walking.

• Don't pick up any snake unless you are absolutely positive it is not venomous.

• Don't pick up freshly killed snakes without first severing the head. The nervous system may still be active and a dead snake can deliver a bite.


Snakes dangerous to man usually fall into two groups:

Proteroglypha- Fixed Fangs; usually dominate neurotoxic
Solenoglypha- Folded Fangs; usually dominate hemotoxic


The fixed-fang snakes (proteroglypha) usually have neurotoxic venoms. These venoms affect the nervous system, making the victim unable to breathe.

The folded-fang snakes (solenoglypha) usually have hemotoxic venoms. These venoms affect the circulatory system, destroying blood cells, damaging skin tissues, and causing internal hemorrhaging.

Remember, however, that most venomous snakes have both neurotoxic and hemotoxic venom. Usually one type of venom in the snake is dominant and the other is weak.

No single characteristic distinguishes a venomous snake from a harmless one except the presence of poison fangs and glands. Only in dead specimens can you determine the presence of these fangs and glands without danger.

There are about twenty-seven species of rattlesnakes in the United States and Mexico. They vary in color and may or may not have spots or blotches. Some are small but others, such as the diamondbacks, may grow to 2.5 meters (8 feet) long.


There is little to fear from lizards as long as you follow the same precautions as for avoiding snakebite. There are only two poisonous lizards: the Gila monster and the Mexican beaded lizard. The venom of both these lizards is neurotoxic. The two lizards are in the same family, and both are slow moving with a docile nature.

The Gila monster is a species of venomous lizard native to the southwestern United States and northern Mexico (but not Baja California). A heavy, slow-moving lizard, up to 2 feet long, the Gila monster is the only venomous lizard native to the United States and one of only two known species of venomous lizards in North America, the other being its close relative, the Mexican beaded lizard.

Though the Gila monster is venomous, its sluggish nature means that it represents little threat to humans. However, it has earned a fearsome reputation and is sometimes killed by hikers and homeowners despite being protected by state law in Arizona and Nevada.

Venom is produced in modified salivary glands in the Gila monster's lower jaw, unlike snakes, whose venom is produced in the upper jaw. The Gila monster lacks the musculature to forcibly inject the venom; instead, the venom is propelled from the gland to the tooth by chewing. Capillary action brings the venom out of the tooth and into the victim. The teeth are loosely anchored, which allows them to be broken off and replaced throughout life.

Mexican Beaded Lizard

Adult beaded lizards range from 24 inches to 36 inches in length. It is substantially larger than the Gila monster, which only reaches lengths of 12 inches to 16 inches. Although males are slightly larger than females, the animals are not sexually dimorphic.

Both males and females are stocky with broad heads, although the males tend to be broader. The beaded lizard's scales are small, bead-like and non-overlapping. Except for the underside of the animal, the majority of its scales are underlaid with bony osteoderms.

Their base color is black and marked with varying amounts of yellow spots or bands, with the exception of H. h. alvarezi, which tends to be all black in color.

The beaded lizard has a short tail which is used to store fat so the animal can survive during months of estivation. Unlike many other lizards, this tail does not autotomize and cannot grow back if broken. The beaded lizard has a forked black tongue which it uses to smell, with the help of a Jacobson's organ; it sticks its tongue out to gather scents and touches it to the opening of the organ when the tongue is retracted.

The venom glands of the beaded lizard are modified salivary glands located in the animal's lower jaw. Each gland has a separate duct leading to the base of its grooved teeth. When biting, the beaded lizard hangs on its victim and chews in order to get its venomous saliva into the wound. Although its jaw grip is strong its unsocketed teeth are easily broken off at their bases.

The beaded lizard's venom is a weak hemotoxin and although human deaths are rare, it can cause respiratory failure. It consists of a number of components, including L-amino acid oxidase, hyaluronidase, phospholipase A, serotonin, and highly active kallikreins that release vasoactive kinins. The venom contains no enzymes that significantly affect coagulation. Almost all documented bites (eight in the past 100 years) have resulted from prodding captive animals with a finger or bare foot.

The komodo dragon (Varanus komodoensis), although not poisonous, can be dangerous due to its large size. These lizards can reach lengths of 3 meters (10 feet) and weigh over 115 kilograms (253 pounds). Do not try to capture this lizard.

Note: Snakes make a good survival meal. (But not worth getting injured over if you don't know what you are doing.)

Stay Prepared! Stay Alive!


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