Have you ever seen a lizard hurtling over your head? How about a frog sailing down from the tree tops? I’m not making these animals up. They belong to one of earth’s most astonishing groups of animals.
Gliders travel through the air, but they don’t fly. Instead, they glide. What’s the difference? Well, to get itself off the ground, a bird, bat, or insect has to generate a force called lift. A flying animal generates lift using its wings, which are attached to powerful flight muscles. These wings move and bend in complicated motions to counteract the force of gravity.
Gliding animals do not have muscle-powered wings. Instead, most gliding animals have special flaps or folds of skin called patagia. Like wings, the patagia generate lift—but only after the animal is already moving through the air.
When chased by a snake, a Draco lizard leaps from its tree. Instead of plunging to its death, it spreads out its rib cage into two elegant airfoils covered with skin. As air rushes over them, these airfoils—the patagia—generate lift to keep the lizard from falling straight down. The lizard does steadily descend toward earth, but it is also riding the air. It can change directions, pull a U-turn, and control where it wants to go. In the process it can travel hundreds of feet before landing on another tree or on the ground.
The patagia of Wallace’s frogs lie between their toes. These frogs usually live up in the trees, but when it is time to mate or lay eggs, they leap, spread out their toes, and glide to earth.
Earth’s most astonishing gliders may be five species of gliding snakes. These snakes don’t have patagia. Instead, they flatten out their bodies and “crawl” through the air. Scientists aren’t sure if the crawling motion helps generate lift, or if lift comes mainly from a snake’s flattened shape, but the animals can glide more than 100 feet before landing.
Most of earth’s gliding animals live in Southeast Asian rainforests, which are home to more than eighty species of gliding lizards, frogs, snakes, and mammals. In North America, we have only two gliding animals: Northern and Southern flying squirrels. Despite their name, flying squirrels don’t fly. They glide—and are adorably cute! Want to see one? Try shining a flashlight on a bird feeder at night!
A male Draco lizard extending his gular flag (throat flap) and patagi (wings). While not capable of powered flight Dracos often obtain lift in the course of their gliding flights. Glides as long as 200 feet have been recorded, Wikimedia
Wallace's frogs live almost exclusively in the trees, and leap and "fly" from tree to tree or to bushes. The membranes between their toes and loose skin flaps on their sides catch the air as they fall, helping them to glide, sometimes 50 feet or more, to a neighboring tree branch or even all the way to the ground. They also have oversized toe pads to help them land softly and stick to tree trunks. Wikimedia
Flying squirrels are able to glide from one tree to another with the aid of a patagium, a furry, parachute-like membrane that stretches from wrist to ankle. Their long tail provides stability in flight. Wikimedia
There are five recognized species of flying snake, found from western India to the Indonesian archipelago. They flatten out their bodies and parachute or glide using their ribs to become flat, and then they whip their bodies in a fast, rhythmic S-shape to stay airborne. Wikimedia
Illustrated with arresting photographs, Sneed B. Collard's Catching Air: Taking the Leap with Gliding Animals takes us around the world to learn why so many gliders live in Southeast Asia, and to find out why this gravity-defying ability has evolved in Draco lizards, snakes, and frogs as well as mammals. Why do gliders stop short of flying, how did bats make that final leap, and how did Homo sapiens bypass evolution to glide via wingsuits and hang gliders―or is that evolution in another guise?
MLA 8 Citation
Collard, Sneed B., III. "Meet Earth's Incredible Gliders." Nonfiction Minute,
iNK Think Tank, 11 Apr. 2018, www.nonfictionminute.org/
Can you name the world's fastest mammal? How about the biggest shark? If you said the cheetah, and the whale shark, you’re right! It's safe to say that we will probably never discover faster, or bigger, animals. However, it is still possible to find small animals that can set new records for being tiny.
Take frogs, for example. For many years, two kinds of frogs were tied for the honor of being the world's smallest. One species lives in Cuba, the other in Brazil. These frogs are so small that one can perch its whole body on a United States dime. Look at a dime and imagine an adult frog sitting there!
Recently, those two little species from Cuba and Brazil lost their title as Earth's smallest frogs, thanks to two scientists from the United States. They were herpetologists (scientists who study amphibians, including salamanders and frogs). In 2009 these scientists were studying frog calls on Papua New Guinea a large island nation north of Australia, in the Pacific Ocean.
The scientists were recording frog calls at night. All around, they heard chirping sounds that came from dead leaves on the forest floor. "Probably insects," they thought, but they decided to check. They searched among the leaves but found nothing. Frustrated, they grabbed whole handfuls of leaves and stuffed them into a clear plastic bag. Then they slowly searched through the bag, leaf by leaf. A small frog hopped off one of the leaves!
When I say "small frog," I mean one that can sit on a dime with room to spare. It was just 7.7 millimeters long. That's less than a third of an inch. Though the scientists later discovered another slightly bigger relative, the first one is now officially Earth's smallest frog—and Earth's smallest four-footed animal.
These tiny frogs are hard to catch. They can leap 30 times their own length. But the herpetologists managed to catch quite a few, take photos of them, and learn about their lives, close up. It wasn't until January 2012 that the scientists announced their discovery. Since this frog was discovered near a village called Amau, it was given the scientific name of Amauensis. Eventually, people may come to call it the Amau frog.
In the world of science, the tiny Amau frogs are very big news.
The tiny Amau frogs were discovered just before Laurence Pringle's book on frogs was published--too late to include this big news. At the end of his book FROGS!, Larry has an Author’s Note called “A Life Full of Frogs” in which he tells about his close encounters with frogs as a child, as a father, as a wildlife photographer, and as a neighborhood ecologist acting locally to protect and even create anuran habitats. His relationship with frogs continues to this day. He says, "Our Spring evenings are sweetened by a chorus of spring peepers from the neighborhood wetland forest. Also, almost every day we visit our backyard garden pond. Several green frogs, large and small, live there. There are tadpoles of both green frogs and gray tree frogs."
Pringle, Laurence. "Tiny Frogs Are Big News." Nonfiction Minute, iNK Think Tank, 13 Oct. 2017, www.nonfictionminute.org/the-nonfiction-minute/tiny-frogs-are-big-news.
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