Introduction
Snakes have generated more fear and misunderstanding than any other group of animals. And psychologists have proven that a fear of snakes is acquired; we are not born with it. Once people learn some of the interesting facts about snakes and discover that most of them are harmless and beneficial, their aversion may diminish. With patience and understanding, almost anyone can overcome a dread of snakes and actually enjoy studying them. One thing is certain—even people with a well-developed fear of snakes are curious about them.
(top) Eastern garter snake eating a leopard frog. (middle) Prairie kingsnake shedding skin. (bottom) Bullsnake eating a mouse.
Missouri, with its wide variety of wildlife habitats—prairies, Ozark hills and valleys, swamps, marshes—has a total of 46 species and subspecies of snakes. (A subspecies is a geographic race of a species.) Most of our snakes are harmless. Although many may bite in self-defense, their bite usually produces nothing more than harmless scratches. There are only five species of venomous snakes in all of Missouri and we describe them in a separate section of this web page.
Snakes are members of the Class Reptilia, a group that also includes turtles, alligators, crocodiles and lizards. Snakes and lizards are similar in many ways, but there are some important differences. A clear, non-movable scale covers the eyes of all snakes, whereas most lizards have moveable eyelids. Most lizards have legs, but some are legless. The slender glass lizard, which lives in the southern half of Missouri, is an example; it looks like a snake because it has no legs, but like all our lizards, the slender glass lizard has moveable eyelids and external ear openings, both of which are lacking in snakes. In addition, lizards have a pair of lungs, while most snakes have an elongated right lung and either no left lung or only a rudimentary one.
Although snakes are legless, they are able to move about with ease. A snake's backbone has from 200 to 400 vertebrae, depending on the species, which permits extreme flexibility. Snakes move forward by a side-to-side movement, or in a straight line by literally walking on their ribs. All snakes can swim.
Snakes must swallow their food whole, and some can engulf animals three times the diameter of the snake's head. The lower jaws of snakes are loosely joined to the skull and the upper jaws are moveable. A snake grasps its prey (fish, frog, mouse) by the head and engulfs it by advancing first one side of the jaw and then the other. The snake's teeth also help it swallow. The teeth are sharp and curve toward the rear of the mouth. They hold the prey and prevent its escape. Some snakes, such as water snakes and garter snakes, eat their prey alive, while venomous snakes usually inject venom into the animal and swallow it after it is dead. Several Missouri snakes, such as the rat snakes, kingsnakes, milk snakes and bullsnakes, kill by constriction. The snake grasps the prey in its mouth and immediately wraps several tight coils around it. Thus prevented from breathing, it dies from a lack of oxygen. Then the snake swallows its prey.
(top) Diamondback water snakes being born. (bottom) Rough green snake hatching.
The snake's long, forked, extendable tongue is often thought to be dangerous; in fact, it is completely harmless. Snakes and lizards use their tongues to pick up odors that are transferred to special sense organs in the roof of the mouth. The food habits of Missouri's snakes are as varied as the types of snakes we have. Some, such as the rough green snake, eat insects and insect larvae. Others, like the water snakes, eat fish, frogs, tadpoles or crayfish. The black rat snake and bullsnake eat rodents and small birds and their eggs. Kingsnakes also eat rodents and are important predators on lizards and other snakes, including venomous snakes. All snakes shed their outer layer of skin periodically as they grow. Young ones usually shed once every four or five weeks during warm months, whereas adults may shed once every six or eight weeks during their active season. In the case of rattlesnakes, a new segment is added at the base of the rattle at each shedding. In Missouri, rattlesnakes may shed from two to five times a year. As the rattle becomes longer, the old segments weaken and may break off, so it is not possible to determine the age of a rattlesnake by counting the segments in the rattle. In Missouri, snakes normally breed in the spring, soon after they emerge from winter dormancy. Studies show, however, that a few species may breed in the fall. About half of Missouri's snake species lay eggs; the rest give birth to fully developed young.
Some egg-laying species are black rat snakes, bullsnakes, kingsnakes, racers, worm snakes, ring-necked and rough green snakes. The size of the egg depends on the species; the number of eggs produced depends on the size of the female. The larger the female, the more eggs she can produce. Snake eggs are elongated and have a tough, leathery shell. Females select rotten logs or stumps, leaf litter or sawdust piles in which to deposit their eggs. As a young snake develops within the egg, a small egg tooth grows on the tip of its snout; the snake uses this tooth to slit the shell when hatching. Afterwards, the tooth is shed. Snakes usually hatch in late summer or early fall.
Snakes which retain their young until they are completely developed are water snakes, garter snakes, brown snakes, copperheads, cottonmouths and rattlesnakes. This form of reproduction is slightly advanced over egglayers. The young snakes are retained and protected inside the female during their development. Each young snake is protected inside a thin, sac-like membrane containing yolk for nourishment. Some of the young snakes break through the membrane while inside the female and emerge from the female in a tight coil; others break through after being born. Snakes that develop inside the female are normally born in mid to late summer.
The smallest snake native to Missouri is the flat-headed snake (Tantilla gracilis), which averages from 7 to 8 inches (18-20 cm) long. The largest is the bullsnake (Pituophis melanoleucus sayi), which averages from 50 to 72 inches (127-183 cm).
Eastern Massasauga Rattlesnake Missouri’s venomous snakes have vertical “slit” pupils. Eastern Hog-nosed Snake (non venomous) Missouri’s non-venomous snakes have rounded pupils. The rattle is a familiar characteristic of rattlesnakes. Other venomous and non-venomous snakes may shake their tails in dry leaves.
Facts on Snakebites
Few people in Missouri suffer venomous snakebites, despite the fact that there are five venomous species and at least one of them—the copperhead—is commonly encountered. Most bites occur when people are trying to kill or handle the snakes. About 8,000 people are bitten by venomous snakes each year in the United States. Fewer than five die, which amounts to a fraction of one percent. By comparison, about 120 people die annually from bee stings and 150 die when struck by lightning. Encounters with venomous snakes can be prevented if you follow these simple rules:
- Stay away from areas where there may be a concentration of venomous snakes, such as swamps, marshes and bluffs.
- Wear protective footwear in areas where there are likely to be snakes. Thick leather or rubber boots or hightop hiking shoes will protect feet, ankles and lower legs.
- Never place your hands under rocks or logs; do not step over rocks or logs. Step on them first, then over.
- Step lively when hiking. Look the ground over, particularly around large rocks or logs, when you stop to stand or sit.
- Wear rubber boots when fishing in streams that may harbor the venomous cottonmouth. If a cottonmouth falls in your canoe or boat, don’t panic—get to shore and flip the snake out with a paddle, net or fishing rod. Trying to kill the snake in the boat may cause the snake to bite you or cause you to fall into the water.
- Avoid any snake you cannot identify. For current information on snakebite first-aid, contact your nearest American Red Cross.
- In the event of a venomous snakebite, seek medical attention immediately!
Conserving Missouri’s Wildlife
Snakes are not popular creatures in our culture. Just the mention of them evokes the images of evil for most people. But even these animals are having a difficult time surviving, not only because of persecution but also, in large part, because of habitat destruction (deforestation, pollution, urbanization). As with many animals whose numbers are declining, most problems associated with the plight of our native snakes result from a lack of understanding. People traditionally have been brought up to fear and hate snakes; consequently, snakes have not fared well in their relations with man.
As with all other wildlife native to Missouri, snakes are an important part of the natural food chain and play an important role in the balance of nature. As an example, snakes are helpful in reducing populations of destructive rodents and, in turn, are prey to such wildlife as hawks, great blue herons, otters and game fish. Overall, snakes are a fascinating part of the natural world in which we live, and seeing a snake in the wilds of Missouri can add to your outdoor adventures.
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Snakes of Missouri.
Content revision: 2004/05/16
