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It may sound surprising, but sloths can hold their breath for up to 40 minutes, which is longer than many dolphins. They accomplish this by dramatically slowing their heart rate and metabolism while underwater. Sloths are surprisingly good swimmers and often cross rivers in search of food or new territory. Dolphins, despite being marine mammals, usually surface for air every 8 to 10 minutes during normal activity.
This unusual ability makes sloths one of the most unexpected breath-holding champions in the animal kingdom. Their slow lifestyle helps conserve energy in many ways.
© Smithsonian's National Zoo and Conservation Biology Institute