Click to Enlarge A snake has a variety of muscles that help it breathe, eat and move. Muscles attached to a snake's scute scales allow the scales to grip the ground for better traction. Click to Enlarge Rectilinear: (top left photo) Sometimes snakes inch forward (top) in a straight line. This is called rectilinear locomotion. They can't go backwards this way, but snakes are so fl exible that they can turn around in a small space. Serpentine: (top right photo) Many snakes travel a continuous S-shape path (above). They push against the ground or objects to propel themselves forward. Snakes also use this serpentine method of moving to swim through the water. Concertina: (bottom photo) Snakes seem to expand and contract like an accordian when they climb trees. They pull the lower part of their body up and push the forward part of their body higher.   What's in a Slither? by Lisa LaCombe, illustrations by Mark Raithel How do snakes glide, creep, climb, burrow, strike and swim? Do you like snakes? Many people believe snakes are creepy, slimy and dangerous. It's true that they are unusual animals and a few of them are venomous, but that just makes snakes more fascinating to observe and study. The more we learn about snakes, the more interesting these animals become. For example, snakes have a unique method of moving from one place to another. Most animals walk. Some animals swim or fly, but snakes slither. When you think about it, that's all they can do because they have no arms or legs. Snakes have a backbone, and each vertebra of this backbone is connected by a ball-and-socket joint like the one in your shoulder. Having a series of ball-and-socket joints gives a snake incredible flexibility. Every vertebra has a pair of ribs attached to it. In some snakes this might add up to 600 ribs! Snakes have a network of specialized muscles along their flexible backbone that allow them to move their long, cylindrical body. These muscles, vertebra and ribs working together permit snakes to slither about with agility, speed and strength across virtually any surface on earth, except ice and snow. Push, Push, Push To move, you have to push against something. You push against the ground with your foot as you walk. Fish use their tails to push them through the water. Snakes push off the ground, using their belly, tail and even their head. Scute scales found on the belly of a snake are a key part of its locomotion. The edges of these scales bite into the ground so they can push off and move themselves. They work like knobby tires to provide traction. A snake's method of movement depends on the size of the snake and the surface it is traversing. Missouri snakes rely on several diff erent methods of locomotion. Most slithering snakes move in an S-shaped pattern. To propel themselves through this pattern, they sequentially flex their muscles and push against the back of each curve. In soft sand, you can see sand they have pushed up at the back of the curves. You'll also see that the entire body of the snake exactly follows the path of the head, just like railroad cars follow the locomotive. Called lateral undulation, this S-shaped motion is a snake's fastest means of locomotion. As the snake moves along it also pushes against rocks, brush or any ground irregularities to help propel it forward. Lateral undulation is also the method all snakes use to swim in water. There are times when snakes can't take an S-shaped path. They might have to travel down a narrow tunnel, for example. In this case, snakes flex strong muscles attached to each scute scale to creep forward like inchworms. Snakes can move well this way, even though we barely see any vertical movement. A good way to picture this type of movement is to imagine gently snapping a straight rope lying horizontally on the ground. Snakes also move with an accordion-like motion. This concertina movement allows them to climb trees. A snake will anchor the forward part of its body, pull its tail up, and then anchor it so it can push its head upwards again. Snakes will also use any available limbs or branches to help them climb. Snakes can also jump by tightly coiling their body like a spring and then releasing it. They don't jump to travel, however. Instead, they sometimes rely on this jumping movement for quick speed to strike at prey or to defend themselves. Many species of snakes live in tunnels under the ground. These cozy little homes are usually borrowed from a former resident, but some snakes are able to burrow beneath leaves or objects on the ground. Put It Into Reverse? Because their scute scales only provide traction for forward travel, snakes can't travel backwards. To turn around, a snake has to point its head backwards and pull its body after it. Because snakes are so fl exible, they can perform an“about face” in a very small area. Is It Venomous? Missouri is home to 52 species and sub-species of snakes. Of these, only five are venomous. If you are exploring outdoors and happen to discover a snake, how do you know whether or not the snake is venomous? The best rule is to keep a respectable distance from snakes until you have learned to recognize them. When learning about snakes, watch them from a distance and note their habitats, colors, patterns and size. Don't bother them. Most snake bites occur when people try to capture or kill snakes. Field guides can help you identify snakes. You can learn about Missouri's most common snakes from the brochure, “Snakes of Missouri,” available at your nearest conservation office. You can also read or download a version at <www.missouriconservation.org/nathis/herpetol/>. Threats to snake populations throughout the world increase each year. For example, the massasagua rattlesnake is listed on Missouri's rare and endangered species list. Habitat loss is the greatest threat to snakes worldwide. Snakes are an important part of Missouri's natural world. They help farmers and home owners by controlling rodent populations. If you see a snake, watch the way it moves and always give it the right-of-way.