Homosassa Spring, Florida — Every winter, the 2,000-pound West Indian manatees of Florida's Gulf Coast seek the warm clear waters of inland springs. There, they congregate and gently linger, feeding on plants amidst schools of jack. Spanish moss hangs from twisted limbs and filters the morning mist. Wood ducks nest overnight in the limbs of the nearby trees and take flight at first light. As the sun further brightens, the manatees meander over to check out the cameras, which are positioned split-surface to capture their exhalations every few minutes above and below the surface.