Was that really a large great white shark cruising through a wave, mere feet from unsuspecting surfers, at a popular Southern California beach last Wednesday?
Or was it another species of shark, or something else entirely, depicted in a widely circulated photo that has generated such a buzz among surfers, particularly those who ride waves at Swami's Beach in the San Diego community of Encinitas?
Although shark sightings had been reported previously off another area beach, this one sparked controversy because of the photograph, which revealed what appeared to be the tail end of a large shark as it swam freely among surfers.
Gary Elliott, who snapped the photo, told CBS News 8 he did not see the apparent shark until he got home and looked at his images. In the same report lifeguards suggested the image was merely that of a surfer "duck diving" beneath the wave. But Ralph Collier, who runs the Shark Research Committee, identified the shark as a probable great white measuring 10-12 feet, "or a little more."
This news might have been especially unsettling to those who recalled the fatal attack by a large white shark on a swimmer off Solana Beach, a mile south of Swami's, in 2008.
Surfers and other scientists, however, remain skeptical. Nick Batcheller, a spokesman for Mitch's Surf Shop just south of Encinitas in Solana Beach, said surfers who come into the shop and who frequent the Swami's lineup are convinced that something about the image is fishy.
"It just doesn't add up," Batcheller said. "If the shark was that big it would be protruding out of the back of the wave."
Christopher Lowe, who runs the Shark Lab at Cal State Long Beach, said the tail does not look like that of a great white. Lowe, who has studied white sharks extensively off Southern California, suggested the tail might have been the fluke of a bottlenose dolphin as it swam sideways through the wave.
Salvador Jorgensen, a white shark expert at Stanford University's Hopkins Marine Station, had basically the same response. "It doesn't really look like a shark tail more than, say, a dolphin sideways in the wave," he said. "But it's impossible to say for sure from the picture alone."
Luke Tipple, an Australia-based marine biologist who has served as a host for numerous nature programs, wrote a blog post about the image under the title, "That's not a great white shark."
Tipple also suggested that if it were a 10- or 12-foot white shark, more of its body would have been evident in the photo. He added that large white sharks simply do not swim along the surface, and implied that the only way the duck-diving surfer theory made sense was if someone used a photo-editing program to remove the surfer's feet.
In the News 8 story, Elliott denied that the image had been altered and made no claim that the subject was, in fact, a large great white. In fact, like other surfers, Elliott was looking forward to paddling out at Swami's, shark or no shark.
"I don't feel threatened in the water at all," he said.