Manatees, Florida

Photograph by Paul Nicklen, National Geographic

Propeller scars mark this manatee—graphic evidence of a too-close encounter with a boat. About one in four of Florida's 360 manatee deaths in 2012 resulted from collisions. Slow-speed zones help, but some boaters resent the restrictions.

See more pictures from the the April 2013 feature story "When Push Comes to Shove."