A curious cuttlefish stares back at the camera from inside The Smithsonian's National Zoo Invertebrate Exhibit. The exhibit, home to dozens of small aquatic and terrestrial species without backbones, closed on Sunday. Meghan Murphy/Smithsonian's National Zoo hide caption

toggle caption Meghan Murphy/Smithsonian's National Zoo

The fossilized remains of a whale that washed up on a shore in what's now Chile more than 5 million years ago. Vince Rossi/Smithsonian Institution hide caption

toggle caption Vince Rossi/Smithsonian Institution

A fish that knows the way to go: the Chinook salmon, which appears to use the Earth's magnetic field to navigate ocean waters and rivers. Jeff T. Green/Getty Images hide caption

toggle caption Jeff T. Green/Getty Images

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