Few animals have contributed to modern medicine in a way quite as improbable as the horseshoe crab. It looks prehistoric because, in evolutionary terms, it is. Horseshoe-crab relatives were swimming in ancient seas hundreds of millions of y...
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A sleeping octopus can look almost ghostly. Its body lies still, its eyes close and its skin may fade toward a pale, uniform color. Then, without waking, the animal seems to erupt into activ...
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High on a mountain in late spring, a patch of snow can suddenly look as though someone spilled watermelon juice across it. The surface turns pale pink, rose red or even crimson, sometimes st...
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In daylight, the water may look ordinary — or even unappealingly reddish-brown. Then darkness falls, a wave breaks, and the shoreline suddenly flashes electric blue. Footsteps sparkle in wet...
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Few wildlife events are as disturbing as a whale stranding. An animal exquisitely adapted to life in deep water suddenly lies helpless on a beach, sometimes alone and sometimes alongside doz...
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Your passport knows exactly how old you are. Your cells are a more complicated matter. Two people born on the same day can reach middle age with very different cardiovascular health, physica...
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Few sights make the Moon seem more theatrical than an early-autumn moonrise. A huge amber disk appears behind trees, rooftops or distant hills, looking far larger than the Moon we see later...
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For decades, coffee has occupied an awkward place in conversations about heart health. It contains caffeine, a stimulant that can temporarily raise blood pressure and make some people feel t...
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A mosquito bite is usually an itchy annoyance that disappears within a few days. During summer and early autumn in the United States, however, one particular mosquito-borne infection repeate...
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On most nights, Americans who want to see the northern lights need to travel a very long way north. Then the Sun becomes unusually active, NOAA issues a geomagnetic-storm watch or warning, a...
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