Ride the Wind: Airborne Journeys of Animals and Plants
At any moment all over the world animals and plants are sailing through the sky Birds and butterflies soar flap glide and flit on journeys of hundreds of thousands thousands of miles Locusts swarm by the millions an airborne airborne river of buzzing insects eating everything in their path Bats flutter their skin-covered wings zigzagging through the night sky Some spiders are balloonists floating on silken threads carried to great heights by the wind Feathery dandelion tufts sail aloft on the gentlest breezes Winged fruits and seeds whirl downward downward through the air spinning like tiny helicopters
All the animals and plants in the world live on the earth as well as above its surface For our planet is made up not only of rocks soil and water but also of the gases in its atmosphere Animals and plants and people too live at the bottom of the atmosphere an enormous ocean of air that reaches hundreds of miles above the solid surface of Earth Animals and plants that make air journeys travel through a layer of the atmosphere called the troposphere which can be up to six miles 9 6 km high Air is a real substance even though it is invisible A bird’s wing pushes against the air in its path and the air pushes back against the wing Birds flap their wings to push through the air the way swimmers use their arms to push through water The support of the air allows birds bats and insects to fly and carries seeds and ballooning spiders aloft
Birds and bats are the only vertebrates animals with backbones that can truly fly Some animals such as flying fish can glide for short distances Because a bat’s wing is a thin skinlike substance supported by the long bones of the bat’s fingers and arms bats can vary the outline outline of their wings quickly and easily and thus make sudden turns in the air Bird feathers weigh very little and have a broad surface that catches the wind Bird bones are often hollow and lightweight and form a strong support for the flight feathers of a bird’s wings The breastbone of most birds supports the muscles used in flying the muscles are the heaviest part of a bird’s body Bird wings vary in shape Some like the gull’s are good for soaring as well as for strong and quick flight Others like the wings of the albatross are broader for gliding while still others like those of the swift are narrower for speed
