Great white sharks can be ferocious predators, but one of these giant fish overestimated its hunting abilities when it crunched down on a sea turtle and then choked to death, according to a tuna fisherman near Japan who described the incident.
This episode is likely a rare one, because while it's uncommon for great white sharks (Carcharodon carcharias) to choke on prey, it's even rarer for them to choke on their meal if it's a sea turtle, said Christopher Lowe, director of the Shark Lab at California State University, Long Beach, who wasn't involved with the case.
That's not because sea turtles go down so easy, however; it's because the reptiles are exceptionally good at avoiding great whites, Lowe said.
"Sea turtles, when they know white sharks are around and white sharks come near them, they have this behavior where they'll turn their backs and they'll point their shells toward them — they'll go sideways," Lowe told Live Science. "It makes it really hard for the shark to get a purchase on the turtle."
This sideways-turning trick is usually enough to deter great whites from chomping down on sea turtles. The only way a shark could successfully catch a sea turtle would be to sneak up on one, Lowe said. If the turtle isn't paying attention, or if the turtle is sick or wounded, then it's doomsday for the turtle.
But in this case, it was curtains for the shark, too.
Fishermen Greg Vella wrote about the incident in an April 19 Facebook post (along with photos of the beast), saying, "I heard chatter on the radio that there was a white shark swimming around with a big sea turtle in [its] mouth. People started to joke about it, so I did not pay it any more attention."
The next day, however, the shark "was found dead, near the bait receivers, tangled in some netting," Vella wrote. "The captains I interviewed, who saw the mighty shark the day before, said it looked close to death, as it could not dislodge the giant turtle."
Once prey is stuck in their throats, sharks have little recourse, "because they can't move backward to extract things and they don't have hands to pull it out," Lowe said.
And it's not just turtles that can get stuck. Sharks that chow down on porcupine fish — which are spiky and can inflate themselves with water — may find their mouths entirely blocked, which can also block water flowing over their gills.
"White sharks are among the few shark species that must swim to breathe, keeping their mouths open, allowing fresh, oxygen-rich seawater to flow in and over their gills," said Andrew Nosal, an adjunct assistant professor of environmental and ocean sciences at the University of San Diego, who was not involved with the great white's case. "Anything that obstructs this one-way flow could cause the shark to suffocate and die."
It's surprising to hear about a great white eating a sea turtle, because tiger sharks — "which have distinctively curved and serrated teeth that are very effective at cutting through flesh, bone and other hard substances, such as turtle shells" — are more typical connoisseurs of these creatures.
"Sea turtles are much less common in white sharks' diets," Nosal told Live Science.
Great whites, however, are known to choke on other prey, including elephant seals, David Ebert, a shark scientist and the director of the Pacific Shark Research Center at Moss Landing Marine Laboratories in California, told Live Science. There's even a case of a Greenland shark choking on a moose. (Luckily, two Canadians saved the shark. The moose was already dead.)
In this case, however, no one involved got a happy ending — not the shark, not the turtle and not even the bystanders who witnessed the spectacle. "The commercial guys were bummed, as white sharks do not bother their commercial fishing, and most certainly do bother the things that eat our catch," Vella wrote. "The shark weighed 4,500 pounds [2,040 kilograms]."