Pelagic crabs (Pleuroncodes planipes), also know as red crabs or tuna crabs are episodic visitors to California’s coastline. The species is benthic (bottom dwelling) for most of its life cycle. In the Spring, they migrate upward in the water column to feed and breed. They become subject to currents and large numbers are sometimes stranded on the shoreline, forming heaps a foot or more deep. This occurs more frequently in Baja California but episodically, particularly during El Niño years when prevailing currents reverse, they appear on southern California beaches. Biologists consider their migrations a significant source of energy transport as they attract larger animals like tunas, baleen whales and sea birds to feed. Pictured here are strandings at La Jolla and Ocean Beach. Underwater images were captured in an underwater “river” of crabs off of Isla Coronado Norte, Baja California.