A visitor holds up her toy bunny to the aquarium glass in front of Aurora the Russian polar bear at the Sao Paulo Aquarium in Sao Paulo, Brazil, Thursday, April 16, 2015. (Photo by Andre Penner/AP Photo)

These little grizzly bear cubs had fun making a real splash when their mum took them for a dip to learn how to fish. Kamchatka, Russia. (Photo by Marco Mattiussi/Solent News & Photo Agency)

A view of fluffy toy bears displayed for attraction outside the windows of a hotel in Yantai in Shandong province Thursday, January 6, 2022. (Photo by Tang Ke/Future Publishing via Getty Images)

A black bear cub performs for its mum at the Pocosin Lakes National Wildlife park in North Carolina, US in January 2022. (Photo by Jennifer Hadley/Animal News Agency)

Members of the Coney Island Polar Bear Club warm up before swimming at the beach at Coney Island in New York, December 15, 2013. (Photo by Eric Thayer/Reuters)

TCU Horned Frogs twirler performs at halftime of the game against the Baylor Bears at Amon G. Carter Stadium in Fort Worth, Texas, USA on November 6, 2021. (Photo by Kevin Jairaj/USA TODAY Sports)

A grizzly bear waves its paw at a vehicle on the road to Nemrut Crater Lake in Tatvan district of Bitlis, Turkiye on August 24, 2023. (Photo by Muhammed Selim Korkutata/Anadolu Agency via Getty Images)

Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)