The shark that caused a sensation when a photo of its fin slicing through the waters off Cape Cod behind a frightened kayaker was distributed worldwide might not have been a man-eating great white after all.

The state's top shark expert says the fin likely belonged to a harmless basking shark, a giant fish that feeds on nothing but plankton.

Greg Skomal of the Massachusetts Division of Marine Fisheries says based on the fin's shape and the depth at which the fish was swimming, he's almost positive it was a basking shark.

He says a basking shark's fin is more rounded at the top and basking sharks swim closer to the surface.

Of course, Skomal says, there really are great whites in Cape Cod waters.