猶他州科羅拉多河上的獨木舟玩家。PHOTOGRAPH BY BEN HORTON, NAT GEO IMAGE COLLECTION

鯊魚礁水族館（Shark Reef Aquarium）的金點魟（bigtooth river stingray）。這種魟魚生活在巴西河流的泥濘河底。PHOTOGRAPH BY JOEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK

極度瀕危的長絲𩷶（giant pangasius catfish）。 PHOTOGRAPH BY JOEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK