Pluff Mud

Bottlenose dolphins in the salt marshes of South Carolina and Georgia deliberately throw themselves onto mud banks at full speed, grab fish off the exposed shore, and slide back into the water. They land on their right side every time. Nobody can fully explain why.

The behavior is called strand feeding. It was first documented in 1971 by H. D. Hoese in the shallow tidal marshes of coastal Georgia. Along the East Coast, it occurs daily only in a roughly hundred-mile stretch of coastline from southern South Carolina through Georgia, nowhere else in the United States. The Lowcountry Marine Mammal Network says the region’s pluff mud banks provide the ideal surface: firm enough to slide on, soft enough not to injure a 400-pound animal hitting the ground at speed.

The sequence starts at low tide. Two to six dolphins work together in a narrow tidal creek, using echolocation to track a school of mullet or menhaden through water so murky that nothing is visible from the surface. They circle, tighten, and herd the fish toward an exposed bank. When the school is pinned against the mud, the dolphins make a synchronized rush toward shore. The force of their bodies displacing water creates a bow wave that pushes the fish up and out of the creek onto the bank. The dolphins follow the wave. They surge out of the shallows and slide onto the mud, landing on their right sides, and grab the flopping fish off the ground

Every documented strand-feeding dolphin lands on its right side. The consistency is absolute and unexplained.