Manatees On Fort Lauderdale Beach Surprise Swimmers (VIDEO)

Swimmers were treated to the surprise of a lifetime Sunday when a group of manatees cavorted in shallow waters at Fort Lauderdale Beach.

The sea cow invasion was caught on tape by YouTube user Craig Hossack, whose clip shows five or six manatees swimming right up to the crowded beach as onlookers gawked.

While it's not entirely clear what the rowdy manatees were up to -- the South Florida Sun-Sentinel suggested their play was more about nursing than mating -- lifeguards worked to clear the immediate area surrounding the group, who reportedly enjoyed their audience for half an hour before moving along.

West Indian manatees aren't affected by changes in water salinity and can be found in Florida's rivers, estuaries, and coastal waters of the Atlantic Ocean and Gulf of Mexico. Fortunately for the swimmers in Fort Lauderdale, the gentle giants feed on sea grass.

View more manatees: images and captions courtesy of International League of Conservation Photographers.