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Stingrays, with their wide, flat bodies, may not look like fish, but they are. They are related to sharks, and like their shark cousins, they do not have bones. Instead, their bodies are supported by cartilage—the same material that you feel inside the tip of your nose. Stingrays have broad fins that run the full length of their bodies, giving them a flat, roundish shape. To swim, some stingrays move their whole bodies in a wavy motion that propels them through the water. Other species flap their fins like bird wings and „fly“ through the water. Stingrays have tails that are armed for defense. Some kinds of stingrays have a spine in their tail with a very sharp point and edges that are serrated or notched. Many species, including the exotic-looking blue-spotted stingray, have venom that is delivered through their tails. That venom, and the spine itself, can be dangerous to humans. Stingrays prefer shallow, near-shore waters in warm parts of the world. Here, they spend most of their time lying partially buried on the ocean floor hiding from predators, like sharks, or waiting for prey to swim by. Their colors usually match the mud or sand they hide in. While a stingray’s mouth is on the underside of its body, along with its nostrils and gill slits, its eyes are on the top. Scientists don’t think they use their eyes for hunting very much though. Instead, they use special sensors called ampullae of Lorenzini, which can detect the tiny electrical charges emitted by their prey. Prey for stingrays includes clams, oysters, shrimps, crabs, and mussels. When they find dinner, stingrays crush their meal using strong jaws. Generally, female stingrays give birth once a year. They usually have two to six young at a time. While a baby stingray is still inside its mother, it grows to be quite large and developed so that when it’s born, it looks like a little adult. From birth, the young stingray is able to fend for itself.
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Get the dirt on our planet and what makes it so awesome.
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Crossing a beach to get to the sea, a two-foot-tall Humboldt penguin waddles over what appears to be a cluster of large boulders. Suddenly one of the rock-like objects rises up and barks! The penguin is stepping on sea lions lounging on the shore. Sea lions prey on Humboldt penguins in water but are too slow to catch them on land. The bird continues to ruffle feathers as it climbs over more annoyed sea lions. But it finally makes it to the ocean and dives in for a swim. A GOOD SPORT Humboldt penguins live along the shores of Peru and Chile, two countries in South America. Named for a chilly water current that flows through their coastal range, these birds are excellent swimmers. Their torpedo-shaped bodies can shoot through the water at speeds of 30 miles an hour. And they can dive up to 500 feet underwater in search of snacks such as fish, shrimp, and squid. When the birds need a break from swimming, they come ashore. Getting around on land isn’t always easy. Parts of their habitat feature rocky seaside cliffs. Luckily the animals have some built-in climbing gear: They use sharp claws on their webbed feet to grip onto rocks as they move across the rugged landscape. The animals also put their climbing skills to use when they have to scramble over sunbathing sea lions blocking their path to the ocean. THINK PINK During the hottest months of the year, temperatures in the Humboldt penguin’s home can reach triple digits. The animal has ways to beat the heat though. It sports patches of bare, pink skin around its eyes and at the base of its bill. The bird expels body heat through these featherless spots. This little guy’s athletic abilities and its pink patches make it one colorful penguin! Check out the book Penguins vs. Puffins for more about these amazing birds! Watch a YouTube playlist all about penguins. Text by Andrea Silen, NGS Staff
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A female red-eyed tree frog has laid a batch of eggs on a leaf. She chose the spot carefully—the leaf hangs over a pond. When the eggs are ready to hatch, the tadpoles inside start swirling around vigorously. The activity breaks each egg open, releasing the little tadpoles. All the tadpoles wash down the leaf in a little stream of moisture from the hatching eggs, and—plop! plop! plop!—they land in the pond below. Feeding on tiny insects, the tadpoles live in the water they fell into until they metamorphose, or develop, into little brown froglets. At this point they leave the water and climb up nearby trees to live as tree frogs. By the time they’re adults, the frogs have turned a striking green, with blue-and-yellow striped sides, orange or red feet, a flash of blue on their thighs, and big red eyes. The bright colors are a defense mechanism. Being green helps the red-eyed tree frog blend in with tree leaves. If the green camouflage fails and a predator spots a sleeping frog, it swoops in for what it thinks will be a tasty meal. But the awakened frog’s eyes pop open, revealing their startling bright red color! Also, when the frog rushes to get away, it untucks its brightly colored legs. The predator is often so surprised by these sudden flashes of color that it is momentarily confused and hesitates. And while it does, the frog has a split second to make its escape!
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Goblin Shark
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Although Nile crocodiles resemble armored tanks with huge, teeth-filled mouths, these reptiles are unusually attentive parents. When a large male croc spots a female that catches his eye, he bellows and splashes, slapping his snout on the water to get her attention. He grunts and growls, and sometimes, inhales as hard as he can, submerging his snout and blowing water through his nostrils, producing a fountainlike spray. The female croc is ready to lay her eggs nearly two months after mating. She scouts the area for a suitable nest site in which to lay the eggs, usually digging a hole on a riverbank, shoreline, or dry streambed. She deposits from 25 to 80 eggs in the nest, then settles in for a long vigil. For a reptile, it’s an unusual display of devotion. Other reptiles lay their eggs, then move on. The female croc, however, will keep constant guard over the nest during the three-month incubation period, leaving only to cool off in a nearby shady spot or for a quick dip in the water. The male is usually close by to help scare off predators. Just before hatching, the young crocs send out high-pitched sounds—a signal for help. The female digs up the nest. The mother croc then carefully picks up the 12-inch- (30.5-centimeter-)long hatchlings in her mouth and carries them to the water. The young crocs live under their mother’s protection for up to two years, feeding on insects and small fish and growing about a foot (about 30 centimeters) each year.
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Get pictures and fun facts about eight wacky houses.
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Trudi Trueit has written more than a hundred books for young readers, both fiction and nonfiction. Her love of writing began in fourth grade when she wrote, directed, and starred in her first play. She went on to become a TV news reporter and weather forecaster, but she knew her calling was in writing. Trueit is a gifted storyteller for middle-grade audiences, and her fiction novels include The Sister Solution, Stealing Popular, and the Secrets of a Lab Rat series. Her expertise in nonfiction for kids comes through in books on history, weather, wildlife, and Earth science. Born and raised in the Pacific Northwest, Trueit lives in Everett, Washington.
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A chameleon sits motionlessly on a tree branch. Suddenly its sticky, two-foot-long tongue snaps out at 13 miles an hour, wrapping around a cricket and whipping the yummy snack back into the reptile’s mouth. Now that’s fast food dining! And the chameleon’s swift eating style is just one of its many features that’ll leave you tongue-tied. COLORFUL CRITTERS Chameleons mostly live in the rain forests and deserts of Africa. The color of their skin helps them blend in with their habitats. Chameleons that hang out in trees are usually green. Those that live in deserts are most often brown. They often change color to warm up or cool down. (Turning darker helps warm the animals because the dark colors absorb more heat.) They also switch shades to communicate with other chameleons, using bright colors to attract potential mates or warn enemies. So how exactly do chameleons change colors? The outer layer of their skin is see-through. Beneath that are layers of special cells filled with pigment—the substance that gives plants and animals (including you) color. To display a new color, the brain sends a message for these cells to get bigger or smaller. As this happens, pigments from different cells are released, and they mix with each other to create new skin tones. For instance, red and blue pigment may mix to make the chameleon look purple. EYES EVERYWHERE Over 150 species of chameleons exist, ranging from the size of your thumbnail to that of a house cat. Some species of chameleon (such as the tiger chameleon) are endangered, but others (like the Drakensberg dwarf chameleon) are not. No matter their differences, all chameleons have a prize pair of eyes. Their peepers can move in two different directions at once, giving the lizards a panoramic view of their surroundings. This eye-popping reptile really knows how to scale up the cool factor. Text by Meghan Modafferi / NGS Staff
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Scientists mixed up this dino with Brontosaurus.
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