while swimming in great-white country.
The high rate of survival may have to do with a phenomenon known as the âbite, spit, and waitâ thesis of great-white behavior. First advanced by Dr. John McCosker, senior scientist at the California Academy of Sciences, the thesis explains both terminal attacks and attacks aborted after a single bite. According to McCosker, great whites have the astonishing capacity to assess, in the microsecond of a first bite, the caloric value of potential prey. If the shark determines that the prey isnât worth the effortâthat is, wonât return as much energy as the shark will expend in attacking and eating itâit breaks off the attack after a single bite. Depending on the ferocity of the bite, the prey may or may not survive.
But if the first bite tells the shark that the prey contains an energy bonanzaâas would a nice fat seal, for example, or a sea lionâit will hang around after the first bite, wait for its prey to bleed to death, and then come back to finish the meal.
In general, large great whites perceive human beings as too bony to bother with, so they often depart after that first bite. Of course, when a 2,000- or 3,000-pound fish tastes a 170-pound man, withdrawal can be too little, too late. I will never forget a coronerâs postmortem photographs of a young man killed in the Neptune Islands off South Australia. The shark must barely have grazed him before recognizing its mistake, for aside from one deep cut in a thigh and a nasty wound on one hand and wrist, the victim was unharmed. In the photographs he looked as if he was asleep. Sadly, however, the big sharkâs big teeth had opened two arteries, and the man had bled to death before he could reach the shore.
Some white-shark victims insist that they felt no pain at all when they were attacked, only a
thud
as they were struck and then a feeling of being tugged, as the sharkâs scalpel-sharp teeth severed flesh and bone. A friend of ours who lost a leg to a white shark while snorkeling off Australia recalled, âI couldnât see it, but I knew exactly what had me. It had me by the leg and was pulling me down. I thought for sure I was going to drown. Iâve never been so relieved in my life as when I felt my leg let go.â Luckily for him, a boat was nearby, someone aboard knew how to tie a tourniquet around his thigh, and he made it to a hospital.
From the swimmerâs perspective, the best thing about great whites is that although they exist worldwide, theyâre extremely rare everywhere. Nature, in its infinite and eternally astonishing wisdom, determined that an apex predator (the absolute top of the food chain) as powerful and devastating as a great white should not exist in vast numbers: the marine food chain couldnât support them. So nature decreed that great whites would breed relatively late in lifeânot until theyâre at least twenty years oldâand would bear relatively few young, only some of which would survive to adulthood.
Tiger Sharks
Tiger sharks, too, are genuinely dangerous to man. Theyâve been responsible for several attacks off Hawaii in recent years, and itâs widely believed, with good reason, that they pose more of a threat to humans than do great whites. Tigers may not be as big or as robust and heavy as great whites, but a fifteen-foot, fifteen-hundred-pound tiger shark is plenty big enough; there are more of them, for they pup many more young than great whites (though some of the rapacious young quickly eat their brethren), and theyâre ubiquitous. While great whites, as a rule, hang around coastal waters, tiger sharks are completely free-roaming: theyâre fond of coastal waters, they like to enter lagoons at night and hunt in the shallows for prey that often includes smaller sharks, and they also roam the deep.
Once, when I was on a boat over the abyssal canyons off Bermuda, a huge tiger shark cruised
The high rate of survival may have to do with a phenomenon known as the âbite, spit, and waitâ thesis of great-white behavior. First advanced by Dr. John McCosker, senior scientist at the California Academy of Sciences, the thesis explains both terminal attacks and attacks aborted after a single bite. According to McCosker, great whites have the astonishing capacity to assess, in the microsecond of a first bite, the caloric value of potential prey. If the shark determines that the prey isnât worth the effortâthat is, wonât return as much energy as the shark will expend in attacking and eating itâit breaks off the attack after a single bite. Depending on the ferocity of the bite, the prey may or may not survive.
But if the first bite tells the shark that the prey contains an energy bonanzaâas would a nice fat seal, for example, or a sea lionâit will hang around after the first bite, wait for its prey to bleed to death, and then come back to finish the meal.
In general, large great whites perceive human beings as too bony to bother with, so they often depart after that first bite. Of course, when a 2,000- or 3,000-pound fish tastes a 170-pound man, withdrawal can be too little, too late. I will never forget a coronerâs postmortem photographs of a young man killed in the Neptune Islands off South Australia. The shark must barely have grazed him before recognizing its mistake, for aside from one deep cut in a thigh and a nasty wound on one hand and wrist, the victim was unharmed. In the photographs he looked as if he was asleep. Sadly, however, the big sharkâs big teeth had opened two arteries, and the man had bled to death before he could reach the shore.
Some white-shark victims insist that they felt no pain at all when they were attacked, only a
thud
as they were struck and then a feeling of being tugged, as the sharkâs scalpel-sharp teeth severed flesh and bone. A friend of ours who lost a leg to a white shark while snorkeling off Australia recalled, âI couldnât see it, but I knew exactly what had me. It had me by the leg and was pulling me down. I thought for sure I was going to drown. Iâve never been so relieved in my life as when I felt my leg let go.â Luckily for him, a boat was nearby, someone aboard knew how to tie a tourniquet around his thigh, and he made it to a hospital.
From the swimmerâs perspective, the best thing about great whites is that although they exist worldwide, theyâre extremely rare everywhere. Nature, in its infinite and eternally astonishing wisdom, determined that an apex predator (the absolute top of the food chain) as powerful and devastating as a great white should not exist in vast numbers: the marine food chain couldnât support them. So nature decreed that great whites would breed relatively late in lifeânot until theyâre at least twenty years oldâand would bear relatively few young, only some of which would survive to adulthood.
Tiger Sharks
Tiger sharks, too, are genuinely dangerous to man. Theyâve been responsible for several attacks off Hawaii in recent years, and itâs widely believed, with good reason, that they pose more of a threat to humans than do great whites. Tigers may not be as big or as robust and heavy as great whites, but a fifteen-foot, fifteen-hundred-pound tiger shark is plenty big enough; there are more of them, for they pup many more young than great whites (though some of the rapacious young quickly eat their brethren), and theyâre ubiquitous. While great whites, as a rule, hang around coastal waters, tiger sharks are completely free-roaming: theyâre fond of coastal waters, they like to enter lagoons at night and hunt in the shallows for prey that often includes smaller sharks, and they also roam the deep.
Once, when I was on a boat over the abyssal canyons off Bermuda, a huge tiger shark cruised
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