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
Chapter One LAND CROSSINGS WALKING RUNNING AND HOPPING Walking may seem like a boring way for a person to travel but it’s actually cool Really That’s because humans walk unlike any other creature Sure some other animals walk on two legs like chimpanzees or birds But when their feet hit the ground their knees stay bent We keep ours relatively straight If we bent our legs our thigh muscles would need to use more energy to get us moving Instead we take the straighter more energy efficient way Aren’t we smart Other animals have their own super savvy ways to travel across land while working with and against forces like gravity and friction The goal is to stay upright balanced and on the move Tortoises live pretty casual lives so their movements are rrrreeeaaalllyyy ssssllllooowww Cheetahs have dinner to catch so they’re super fast Kangaroos hop sort of like how humans run with the bonus that they rarely get tired Let’s take a saunter 8
