Compare and Contrast
While penguins are technically birds, they have many distinct attributes that set them apart from the much of the animal class Aves. Penguins thrive in many different climates including tropical and temperate zones. These animals can survive temperatures below -100 degrees Fahrenheit. Antarctic penguins have a three-tiered insulation system. First, they have feathers that act like tiles on a roof, with longer feathers overlapping smaller, fluffier ones. In essence, water-proofing. Beneath that, penguins have a thick layer of fat that provides an extra buffer from the elements and retains body heat. A third special adaptation in the penguin that isn't found in most birds is its ability to recycle its own body heat. Blood flows pre-cooled to the extremities and warmed going to the heart. In the harshest wind-chilled conditions, penguins will huddle together in massive clusters. Most birds don't have a thick layer of fat or longer feathers on top of fluffier feathers. Many species have to find shelter at night, unlike penguins. Only 50 types of birds can live in the Antarctic and far fewer dare to breed there like the penguin. Most penguins spend upwards of 80 percent of their life in water, preferring colder, nutrient laden coasts. Because they only eat seafood, penguins have evolved sharp, hooked beaks to snare fish. They also have a sticky tongue that helps them capture slippery prey. Penguins are superb swimmers because they have webbed feet that serve as diving fins. Their wings have evolved into flippers. Their hydrodynamic bodies allows them to reach speeds of up to 15 mph. Penguins can hold their breath for long periods, allowing them to dive deep for prey. While 150 species of the bird family Antedate specialize in the water, penguins are the fastest and most adept underwater. Penguins live in colonies of up to 1 million but they don't necessarily need protection in numbers....
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