Because snakes are cold-blooded, they must rely on behavior to regulate their body temperature. During the hot part of the day, snakes move to shaded areas. On cool days, they sun themselves on rocks or in warm and open areas. Snakes often seek out paved roads because they are attracted by the heat from the road surface.

Because snakes have a backbone, they are classified in the same group (vertebrates) as fish, mammals, birds and humans. The snake's skeletal system is unique. Snake bones are light and highly movable. The lower jaws and skull are connected by a piece of stretchy material called a ligament. This allows the snake to open its mouth wide and move each jaw independently. Thus, a snake can swallow prey much larger than its head.

Snakes do not have legs, ears or eyelids. Often the sex organs of a snake protrude from the anal plate area, and some might think these are legs.

Snakes use their forked tongues to smell. Their tongue constantly flicks to pick up airborne particles and odors. Once it detects these aromas, the snake inserts its tongue into two holes on the top of its mouth (Jacobson's organ), where its brain interprets the smells. If the snake detects food and is hungry, it will pursue the animal.

Contrary to popular belief, snakes are not slimy. In fact, they feel dry to the touch. The snake's scales and skin help keep it from losing moisture from its body. Snakes shed their skin and eye covering together.

With the warmth of spring, snakes emerge from their winter quarters and search for food and mates. After mating, the male and female snakes separate. Each goes its own way to forage for food until the fall.

Some snakes lay eggs in a damp, protected area where they will hatch in about two months. Other snakes hatch eggs inside the body. Copperheads, rattlesnakes, cottonmouths, garter snakes and water snakes give birth to live young. Once the young have been hatched or born, they are able to take care of themselves. If you find snake eggs around your home or garden, they were laid by a harmless snake.

All snakes are predators, and many are particular about what they eat. Rat snakes eat rats, mice, voles and bird eggs. Water snakes feed primarily on dead, diseased or injured fish. King snakes feed on other snakes, mice, young birds and bird eggs. Some small snakes (the rough green snake) eat insects while others (earth snakes and worm snakes) eat earthworms, slugs and salamanders. Toads are the favorite food of the hognose snake.

When people encounter a snake, they often corner it. Then the snake will hiss loudly, open its mouth in a threatening manner, coil up and strike at the individual or bluff by advancing toward the person. These behaviors are designed to scare off an intruder. They lead, however, to a common misconception that snakes charge or attack people. In most cases, a snake reacts only if it feels threatened. Usually, it crawls away if it can reach cover safely. One exception is the male black racer, which may chase larger animals, including humans, when it is defending its breeding territory.

Habitat
Snakes like to live in damp, dark, cool places where food is abundant. Likely places to find snakes around homes include

Firewood stacked directly on the ground, 
Old lumber or junk piles, 
Gardens and flower beds with heavy mulch, 
Untrimmed shrubs and shrubs growing next to a foundation, 
Unmowed and unkept lawns, abandoned lots and fields with tall vegetation, 
Pond and stream banks with abundant debris and trash, 
Cluttered basements and attics with a rodent, bird or bat problem, and 
Feed storage areas in barn haylofts where rodents abound. 
Identification of poisonous snakes
 
 

Pupil shape
Harmless snakes have round pupils (the black part in the center of the eye). Poisonous snakes have egg-shaped or cat-like (elliptical) pupils. In good light, you easily can see the pupil shape from a safe distance because snakes cannot jump, nor can they strike, from more than one-third of their body length. 
Pit
Poisonous snakes in Missouri also have a conspicuous sensory area or pit (hence the name "pit viper") on each side of the head. The pit looks somewhat like a nostril and helps the snake locate warm-bodied food. It is located about midway between and slightly below the eye and nostril  Harmless snakes do not have pits. 
 

Scale arrangement
The underside scales of a poisonous snake's tail go all the way across in a single row from the anal plate (see Figure 2). The tip of the tail may have two scale rows. Nonpoisonous snakes have two rows of scales from the vent to the end of the tail. This characteristic also can be seen on skins that may have been shed. 
Other features may help you identify a poisonous snake at a distance

Head shape
Usually, poisonous snakes have a triangular (wide at the back and attached to a narrow neck) or "spade-shaped" head. Be aware that many other harmless snakes flatten their heads when threatened and may appear poisonous. 
Distinctive sound
Usually, rattlesnakes sound a warning rattle (a buzz or a dry, whirring sound) when approached. However, many nonpoisonous snakes (black racers, corn snakes, rat snakes, milk snakes and pine snakes) and several poisonous snakes (copperhead and cottonmouth) often vibrate their tails when threatened. The sound produced by this vibration often imitates a rattle or hissing sound when the snake is sitting in dry grass or leaves. 
 
 

You can learn to distinguish poisonous snakes from nonpoisonous species by their color and pattern.

Color patterns and markings
Snakes with lengthwise-striped markings are nonpoisonous. Most solid-colored snakes also are nonpoisonous, except the adult western cottonmouth, which has dark crossbands that often are indistinct. If a snake is marked in any other way, use other characteristics for identification. 
Tail
You easily can recognize young cottonmouths and copperheads by their bright yellow or greenish yellow tails. 
Snake bites
Snake bites occur despite precautions. Most first-aid texts do not encourage victims of snake bites to kill the snake. The victim may wind up being bitten a second time. Whether the snake is poisonous or harmless can be determined within a few minutes if the victim begins to experience pain and swelling at the bite. Also, all snake bites normally are treated with crotalid antivenom, applicable to all poisonous species in the state, so identifying the snake is not as important as it once may have been. 

You should ask your doctor during a regular visit for advice regarding snake bites.

If you are bitten

Stay calm 
Get medical help quickly 
Beneficial aspects of snakes
Before deciding to kill a snake in your yard or garden, consider the many benefits of snakes. Snakes are one of nature's most efficient mouse traps; they kill and eat a variety of rodent pests. Although snakes will not eliminate pests, they do help keep their numbers in check. Some harmless snakes (king snakes, milk snakes and black racers) eat other snakes, including poisonous ones. 

Snake venom has been used to develop a variety of human medicines. One type of high-blood-pressure medicine was developed using information based on chemical secrets contained in snake venom. Researchers are conducting studies using snake poisons in developing treatments for blood and heart problems. Snake venom also is being investigated for controlling some types of harmful bacteria.

Snakes in Missouri are protected by state law. The Wildlife Code of Missouri treats snakes, lizards and most turtles as nongame. This means there is no open season on these animals, and it is technically illegal to kill them. Of course, realistic exceptions exist, such as when a poisonous snake comes in close contact with humans, which could result in someone getting bitten. You should get a collecting permit from the Missouri Department of Conservation before attempting to catch and keep a snake.