by Brendan Bane
White shark descriptions usually begin with hedging: “The white shark is more afraid of us than we are of it,” or, “White sharks only bite people out of curiosity.” Those statements may be true. But no wary description can get around the uncompromising fact: great white sharks (Carcharodon carcharias) are voracious apex predators who have evolved into stupendous oceanic assassins.
At the right time of day, even a 20-foot great white can become nearly invisible. From above, their dark gray tops vanish against the ocean depths. From below, their white bellies blend into light penetrating the ocean surface. That color scheme is the ideal means for adult sharks to go unseen by pinnipeds (seals, sea lions, fur seals).
When a white shark spots a sea lion swimming above, a packet of energy-rich blubber, it initiates a simple, brutal attack plan. Like a bus T-boning a golf cart, the shark accelerates at a perpendicular trajectory, forcefully ramming the mammal at its vulnerable side. Serrated teeth (up to 300 per mouth) tear deep into the sea lion’s flesh. The shark violently shakes its head, sawing into the hide, rendering its owner stunned, bleeding and immobilized.
Many sharks circle back for a second attack, others wait for their prey to bleed out and some drag victims below to drown. Assault tactics vary per prey item. The gargantuan elephant seals of northern California, for example, are targeted at the rump (the seal’s main point of locomotion). White sharks even adjust their attack trajectory when targeting dolphins so as to avoid detection via echolocation.
But marine mammals comprise only one staple of the adult white shark’s diet. They also eat fish (including other sharks), sea turtles, otters and birds. Prenatal white sharks eat each other. Womb-bound great whites consume their weaker siblings and emerge as fully developed, independent predators.
As cosmopolites, white sharks roam the worldwide ocean. Groups are found most often in waters about South Africa, Japan, Chile, the Mediterranean and the Northern Pacific. Californians can lay claim to their own, genetically distinct flavor of white shark, which annually migrates to a kind of white shark café: a marine equivalent of a desert somewhere between the Guadeloupe and Hawaii island chains. What the sharks do while congregating at their café remains a mystery to scientists, but unusual diving behavior suggests they’re up to something.
Unresolved mysteries are reoccurring in white shark biology, despite their fame. After all, colossal, worldwide-swimming predators that dwell from shallow waters to 4,000-foot depths are difficult to track. Scientists monitor traveling white sharks using either satellite telemetry, which reveals where the sharks swim and how they dive, or as of recent, by photographing their dorsal fins, which act as shark ID badges and allow scientists to estimate population size.
The global number of white sharks is a point of contention among experts, but all agree the species warrants protection. By continuing white shark research and limiting the effect of ocean fisheries, we can ensure ample time to appreciate this majestic fish.
White shark pups are born at about 5 feet, mature at 11-13 feet (males) or 15-16 feet (females), and in special cases, can reach lengths in excess of 20 feet. A shark that size may weigh anywhere from 4200 to 5000 pounds. When breaching, adult sharks attain speeds of up to 25 miles per hour, with force great enough to propel their entire bodies above water.
White sharks are capable of traveling great distances. An Australian white traveled from South African coasts to the shorelines of southern Australia and back. Such voyages are fueled by energy-rich fats, which are stored in the animal’s liver.
Many researchers have observed white sharks poking their heads above water, or spy-hopping. Spy-hopping is rare among shark species. Although some speculate the sharks are simply catching a whiff of what’s on the surface, no one understands exactly why they peek.