A great white shark was spotted off Stinson Beach in Marin over the weekend -- and now swimming and surfing in deep water are prohibited through Thursday. Bay Area coastal waters are part of the so-called "Red Triangle" because of the large number of great whites patrolling the waters for prey. How big of a threat do these sharks pose to humans?
Great White Shark Sighting
at 9:00 AM
Douglas Long, chief curator of natural sciences at the Oakland Museum of California and research associate at the California Academy of Sciences