Rattlesnakes (genus Crotalus) have a venomous bite that can inflict serious harm but these unaggressive snakes only strike when threatened, so it is easy in most cases to avoid danger. Most of the 8,000 or so people bit by poisonous snakes annually in the United States, receive bites when attempting to handle, catch or corner a snake. Rattlesnakes will look for any chance to escape confrontation. The telltale rattle gives warning the snake feels threatened.

There are 32 species of rattlesnakes in the United States and many subspecies, with the highest concentrations in the southwest. Smaller populations of perhaps a single species can be found elsewhere in the country. Native to California, several regional species include the Pacific Rattler, Diamondback and Sidewinder.

Rattlesnakes are pit vipers, possessing an indentation (or organ pit) below each eye, which help the animal detect slight changes in air temperature. This allows them to locate warm-blooded prey even in pitch darkness, providing the night air is not so warm as to mask the heat signature. Unique morphology of the rattlesnake includes fangs that lay along the roof of the mouth only folding down to strike. The teeth act like hypodermic needles, pumping poison into the victim. The snake will not hold on to the prey after striking. The stricken animal might even run a short distance before succumbing to the venom. The snake follows and eats the prey whole, unlocking its jaws to swallow the entire body. During this sometimes slow process (depending on the size of the meal) the rattler is completely defenseless. After feeding it will usually be inactive for several days while it digests its meal. A rattler's main diet consists of lizards and rodents.

Rattlers vary in color from brownish gray to greenish and can grow to a length of 6 feet (2 meters). They have distinct, broad triangular heads with narrow necks and yellow eyes. Their pupils are elliptical. The snakes blend in so well with their surroundings that if you disturb a rattler while hiking, for example, you might not know it until you hear the warning sound of its rattle. Do not make sudden or threatening movements towards the snake. Simply move away. Rattlers can span a distance of a few feet very quickly in a strike as they extend their bodies outward. This needn't be from a coiled position.

If bitten by a rattlesnake DO NOT do any of the following:

• Do not make incisions over the bite wound.
• Do not restrict blood flow by applying a tourniquet.
• Do not ice the wound.
• Do not bathe the wound in water.
• Do not suck the poison out with your mouth.

These methods can very well cause additional harm and most amputations or other serious results of a rattlesnake bite are a result of icing or applying a tourniquet.

There are only three things you should do:

• Stay calm.
• Call 911.
• Get to a hospital or poison treatment center immediately.

Most modern over-the-counter snakebite kits consist of a suction device for drawing out venom from the bite wound. This can be helpful in the interim of getting to a hospital or poison center if a kit is handy. Using your mouth is not advisable as the poison can enter the bloodstream through cuts or sores and might be swallowed.

Rattlesnake serum (antivenin) is made from antibodies extracted from horse blood. The serum has its own side effects as the body will have an allergic reaction. However, it's the most effective treatment available. Rattlesnake bites are rarely fatal with less than 1 in 600 resulting in death, and approximately 33% not containing injection of venom at all. However you should assume for your own sake that venom has been introduced and always seek treatment.

To avoid rattlesnake bites some safety precautions will help:

• Wear appropriate hiking boots and thick socks.
• Look at your feet to watch where you step and don't put your foot in or near a crevice that you cannot see into.
• If a fallen tree or large rock is in your path, step up on to it instead of over it, as there might be a snake on the other side.
• Do not turn over rocks or logs.
• If you must move a rock or log, use gloves and roll it toward you, giving anything beneath it the opportunity to escape in the opposite direction.
• Avoid approaching any snake you cannot positively identify as a safe species.
• If you hear the warning rattle, move away from the area and do not make sudden or threatening movements in the direction of the snake.

Depending on weather rattlesnakes may roam at any time of the day or night. If walking at night, be sure to use a flashlight.

Female rattlers carry up to 25 eggs internally until hatched, giving birth to live wriggling snakes. The baby rattlers have a pre button on the tip of the tail which upon molting will start to develop rattles. Each time the snake molts or sheds its skin, a rattle is added. After the first shedding at about 1 week, the single rattle can vibrate against the button to create a small noise. At this point the young leave the mother to search for food. Snakes continue to molt every few months, adding a rattle each time. Many young rattlers become food themselves to birds and other animals and many do not survive their first year. Since rattles can break off, the size of a rattle is not necessarily an accurate indication of age.

There is one species of rattler without a rattle at all. It is the Santa Catalina Island Rattler whose tail simply ends in a stub.