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Axolotls (pronounced ACK-suh-LAH-tuhls) are salamanders! Thes amphibians spend their whole lives underwater. They exist in the wild in only one place on Earth—the lake complex of Xochimilco (pronounced SO-chee-MILL-koh), a network of artificial channels, small lakes, and temporary wetlands that help supply water to the millions of residents in nearby Mexico City. Axolotls have long fascinated scientists for their ability to regenerate lost body parts and for their rare trait of neoteny, which means they retain larval features throughout life. Rather than undergoing typical metamorphosis, axolotls keep their youthful appearance, including their tadpolelike dorsal fin and feathery external gills that fan out from the head. As they age, axolotls simply get bigger and bigger, like amphibious Peter Pans. In rare cases, axolotls have matured past the larval stage and emerged onto land as adult salamanders. Neoteny doesn’t affect the axolotl’s ability to breed. Females mate with males and lay eggs underwater. As Mexico City has grown, the lake complex has shrunk and parts have become contaminated, distressing the axolotl population. The introduction of large numbers of carp and tilapia fish, which compete with axolotls for food and also eat axolotl eggs, has further lowered their population. A 2009 survey suggests there are fewer than 1,200 axolotls in the Xochimilco Lake complex. Axolotls feast on a menu of mollusks, worms, insect larvae, crustaceans, and some fish.
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The ostrich is the tallest and the heaviest of all birds. While the huge ostrich is a bird, it does not fly. Instead it runs. One stride can cover up to 16 feet (4.9 meters)—about the length of a mid-size family car! The bird is speedy, too. It can run just over 40 miles (64 kilometers) an hour for a short distance, and can keep up a speed of more than 30 miles (48 kilometers) an hour over longer distances. The ostrich uses its short wings for balance, holding them outstretched when it runs. Strong legs can also be used for self-defense. An ostrich will kick with a force mighty enough to kill a lion. When danger approaches, an ostrich will often lie low to hide, stretching its neck along the ground. Its feather colors blend with the sandy soil where it lives. From far away, it looks like the ostrich has buried its head in the sand. Many people thought that was what ostriches did when they were trying to hide, but that is a myth. Ostriches live near grazing animals such as wildebeest, antelopes, and zebras. The grazers stir up insects and rodents for the ostriches to eat, and the ostriches warn the grazers to dangers such as approaching lions. An ostrich group, called a herd, numbers about 12 individuals. Male ostriches compete for control of a group of several females. A herd has a dominant male and a dominant female. She mates only with him, though he may mate with other females as well. All the egg-laying females, called hens, lay their eggs in the nest of the dominant female. Then that female—whose eggs are positioned in the center of the nest, the most well-protected spot—and her mate take care of all the eggs in that one nest. Each egg can be up to 6 inches (15 centimeters) long and weigh 3 pounds (1.5 kilograms)!
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Also known as woodchucks, groundhogs spend much of their days alone, foraging for plants and grasses and digging burrows up to 66 feet long.
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You can boil them, bake them, deep-freeze them, crush them, dehydrate them, or even blast them into space. It doesn’t matter—tardigrades can survive practically anything. These eight-legged aquatic animals may be small, but they’re nearly indestructible.
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Dive in to discover seven species of sharks with mind-blowing traits.
"In that deep, dark environment, the sharks need to be able to find each other,"