Introduction MARVELOUS MOTION The kangaroo hops huge distances but never gets tired The flea is as small as a pencil-point but jumps high up to the back of a passing dog The albatross rarely flaps its wings but soars in the air for hours The fishing spider is as big as an adult person’s palm but walks on top of the lake Animals of all shapes and sizes must move their lives depend on it They need to find food or escape from becoming food They need to mate They may need to migrate or defend their territories Whatever the reasons animals are always traveling from place to place and they do so in many amazing ways In this book you’ll meet a collection of animals that move differently You’ll meet those that live on land in air and in water Those that use feet fins or feathers to walk swim or fly You’ll learn about movements powered by muscles waving hairs or flowing liquids Some of these animals are the best at what they do like the can’t catch-me cheetah or the wrist-twisting gibbon Others are wonderful examples of the travel techniques of lots of similar animals like the wing-flapping Canada goose or the fin-undulating triggerfish Yet others seem utterly bizarre like the slime-slipping snail or the rocket-booster squid but make perfect sense for how the animal lives Overall you’ll discover the main methods animals use to get from one spot to another 4
MAY THE FORCE BE MOSTLY WITH YOU No matter how fantastic animal movements appear they can all be explained by science The study of motion is called mechanics It’s called biomechanics when applied to living creatures Whether it’s an airplane or albatross the same rules apply To start or stop movement an object including a living body needs to be pushed or pulled This push or pull is called a force The object also needs to fight forces that are trying to move it in the wrong direction For example let’s look at the four major forces that affect how a bird flies Force 1 Gravity Earth’s pull tries to tug the bird down Force 2 Lift To fight the gravity the bird flaps its wings to create lift This holds the bird up Force 3 Drag Air seems easy to travel through but it’s actually not think how hard it is to walk on a super windy day This drag creates friction against the bird’s body which resists its forward movement tries to push the bird backward and tends to slow it down Force 4 Thrust To fight the drag the bird uses the power of its wings to create thrust which pushes the bird forward 6
Animals on land or in water also have to deal with similar forces One force wants to pull it down the animal has to work to stay up Another force wants to drag it back the animal has to work to move ahead The animals also have to work with and against forces like friction and buoyancy That’s a lot of work In the following pages you’ll learn how animals manage to fight and use these forces to travel along with unique methods and super-well-adapted body parts An astounding variety of creatures live on Earth with an astounding variety of ways to move Want to discover some of them Turn the page and hop to it
