Sharks: The Ocean's Most Misunderstood Predators
Few animals inspire such a potent mixture of terror and fascination as the shark. For most people, the word conjures a single image -- a grey dorsal fin slicing through calm water, a cavernous mouth bristling with serrated teeth, the two-note cello motif from a 1975 film that rewired humanity's relationship with the ocean. This cultural narrative, built on fear and sensationalism, has turned sharks into villains of the natural world. It has also brought them to the edge of ecological collapse.
The reality of sharks is profoundly different from the myth. These animals are not mindless killing machines patrolling for human flesh. They are an ancient, astonishingly diverse group of predators whose lineage stretches back over 450 million years -- predating trees, dinosaurs, and even the colonization of land by vertebrates. There are more than 500 known species of sharks alive today, ranging from the 20-centimeter dwarf lanternshark to the 12-meter whale shark. They occupy every ocean on Earth, from sun-drenched coral reefs to the crushing darkness of the abyssal plain. Some glow in the dark. Some live for centuries. Some can walk on land.
To understand sharks is to confront one of evolution's greatest success stories and one of conservation's most urgent failures.
Ancient Origins: Survivors of Five Mass Extinctions
Sharks are old. Not merely old in the way that crocodilians are old, or horseshoe crabs are old, but old on a scale that challenges human comprehension. The earliest shark-like fossils date to the Late Ordovician period, approximately 450 million years ago -- a time when the most complex life on land was moss, and trees would not evolve for another 90 million years. When the first primitive forests appeared in the Devonian period around 360 million years ago, sharks had already been swimming the world's oceans for nearly 100 million years.
The fossil record of sharks is dominated by teeth and dermal denticles rather than complete skeletons, because shark skeletons are made of cartilage rather than bone. Cartilage is lighter, more flexible, and less metabolically expensive than bone, but it rarely fossilizes. Despite this limitation, paleontologists have assembled a detailed picture of shark evolution from the millions of teeth that have been preserved. A single shark may produce and shed over 30,000 teeth during its lifetime, creating an abundant fossil record.
The most remarkable aspect of shark evolutionary history is their survival through every major extinction event in Earth's history. They endured the Late Devonian extinction (approximately 375 million years ago), the catastrophic Permian-Triassic extinction that wiped out 96% of all marine species 252 million years ago, the Triassic-Jurassic extinction, and the Cretaceous-Paleogene extinction that eliminated the non-avian dinosaurs 66 million years ago. Each time, shark lineages diversified and radiated into new ecological niches, refining a body plan that has proven almost impossibly durable.
The most famous prehistoric shark, Megalodon (Otodus megalodon), patrolled the oceans from approximately 23 to 3.6 million years ago. Based on tooth size -- individual teeth exceeding 17 centimeters (7 inches) in length have been found -- researchers estimate Megalodon reached lengths of 15 to 18 meters (50 to 60 feet) and weighed up to 50 metric tons. It was almost certainly the largest predatory fish that ever lived.
The Great White Shark: Apex Predator of the Open Ocean
The great white shark (Carcharodon carcharias) is the animal most people picture when they hear the word "shark," and it has earned that association through sheer predatory excellence. Adult females -- the larger sex -- reach lengths of approximately 6 meters (20 feet) and weights exceeding 2,000 kilograms (4,400 pounds). Great whites are found in coastal and offshore waters of every major ocean, with notable populations off South Africa, Australia, California, and the northeastern United States.
Ambush Hunting and the Polaris Breach
Great whites hunting marine mammals employ a strategy that contradicts the popular image of the relentless, slow-circling predator. When targeting Cape fur seals at South Africa's Seal Island in False Bay, great whites launch attacks from below with explosive speed. The shark descends to depth, identifies a seal silhouetted against the surface, and accelerates vertically at speeds exceeding 40 kilometers per hour (25 mph). The force of the impact frequently carries both shark and prey entirely out of the water in a spectacular event known as a Polaris breach -- named after the submarine-launched ballistic missile.
Research conducted by the White Shark Trust documented that these ambush attacks are most frequent during the early morning hours, when low light levels give the shark a visual advantage against its silhouetted prey. The success rate of initial strikes is remarkably high -- approximately 55% during optimal conditions -- but drops sharply once the seal is alerted and can maneuver. Great whites rely on overwhelming first-strike power rather than extended pursuit, a strategy that aligns with their physiology as burst predators rather than endurance swimmers.
Thermoregulation
Great whites belong to the family Lamnidae, the mackerel sharks, which possess a remarkable adaptation called a rete mirabile (Latin for "wonderful net") -- a countercurrent heat exchange system in their circulatory network. This allows them to maintain core body temperatures 7 to 14 degrees Celsius above ambient water temperature, making them functionally warm-blooded in their muscles, brain, and eyes. This endothermic capability gives great whites a significant performance advantage in cold waters, enabling faster muscle contraction, quicker neural processing, and sharper vision than their cold-blooded prey.
Hammerhead Sharks: The Cephalofoil Advantage
The nine species of hammerhead sharks (family Sphyrnidae) possess the most visually distinctive head shape of any vertebrate. The laterally expanded, flattened head structure -- technically called the cephalofoil -- has puzzled biologists since the first hammerhead was scientifically described. Why would natural selection produce a head shaped like a sledgehammer?
Function of the Cephalofoil
Decades of research have identified multiple advantages conferred by this extraordinary anatomy:
Enhanced electroreception. The ampullae of Lorenzini -- the electroreceptive organs shared by all sharks -- are distributed across the entire underside of the cephalofoil. In the great hammerhead (Sphyrna mokarran), which possesses the widest head relative to body length, this means the electroreceptive array covers a much larger area of seafloor with each pass. Studies by Stephen Kajiura at Florida Atlantic University demonstrated that hammerheads can detect stingrays buried beneath several centimeters of sand by sweeping their heads in broad arcs, functioning like a biological metal detector.
Near-360-degree vision. The eyes are positioned at the outer tips of the cephalofoil, providing hammerheads with an exceptionally wide visual field. Research published in the Journal of Experimental Biology by Michelle McComb and colleagues confirmed that the scalloped hammerhead (Sphyrna lewini) possesses binocular vision both in front of and behind its head, giving it nearly complete spherical visual coverage -- an advantage no other shark species can match.
Hydrodynamic lift. The broad, flat head functions as a hydrofoil, generating lift during swimming and enhancing maneuverability. High-speed camera footage has revealed that hammerheads execute remarkably tight turns during prey pursuit, using the cephalofoil as a control surface.
Schooling Behavior
Scalloped hammerheads exhibit one of the most unusual social behaviors among sharks: they form massive schools numbering in the hundreds at seamounts and underwater volcanic peaks during daytime hours. These aggregations, observed at locations including Cocos Island off Costa Rica and the Galapagos Islands, appear to be organized by a social hierarchy based on body size, with the largest females occupying the center of the school. At night, the schools disperse as individual sharks descend to depths exceeding 300 meters to hunt squid and deep-water fish. The precise function of this schooling behavior remains debated, with hypotheses ranging from thermoregulation to predator defense to mating display.
The Whale Shark: Gentle Giant of the Tropics
The whale shark (Rhincodon typus) is the largest fish on Earth and one of the most remarkable animals alive. Confirmed specimens have reached lengths of over 12 meters (40 feet) and weights exceeding 20 metric tons, with unconfirmed reports suggesting individuals may grow to 18 meters or more. Despite its enormous size, the whale shark is a filter feeder that subsists almost entirely on plankton, fish eggs, and small schooling fish such as anchovies and sardines.
Filter Feeding Mechanics
A whale shark feeds by opening its cavernous mouth -- which can measure 1.5 meters (5 feet) across -- and drawing in massive volumes of water. The water passes over a series of spongy filter pads located at the entrance to the gill slits. These pads, made of modified gill rakers, trap particles as small as 1 millimeter while allowing water to flow through. A large whale shark can filter over 6,000 liters of water per hour.
Whale sharks employ several feeding strategies depending on food concentration. In areas of high plankton density, they engage in vertical feeding, orienting their bodies nearly perpendicular to the surface and bobbing up and down to draw in surface-concentrated prey. They also perform cross-flow filtration, a technique used in industrial water treatment, in which water and particles flow across the filter surface rather than directly through it, preventing the filter pads from clogging.
Despite their size, whale sharks are remarkably docile around humans. They pose no predatory threat, and swimming alongside whale sharks has become a major ecotourism industry in locations including Ningaloo Reef in Western Australia, Isla Holbox in Mexico, and Oslob in the Philippines. This tourism generates an estimated $47.5 million annually worldwide, making individual whale sharks far more valuable alive than dead.
Bull Sharks: The Most Dangerous Shark You Have Never Heard Of
While the great white shark dominates public fear, many shark biologists argue that the bull shark (Carcharhinus leucas) is the species most dangerous to humans. The reason is not superior aggression or size -- though bull sharks are powerful, stocky animals reaching 3.5 meters (11.5 feet) -- but rather habitat overlap. Bull sharks are the only large shark species that can tolerate and thrive in freshwater.
Freshwater Tolerance
Most sharks are obligate marine animals -- their blood chemistry requires the high salt concentration of seawater to maintain osmotic balance. Bull sharks have evolved a unique physiological adaptation: their kidneys and rectal glands can regulate salt concentration across a wide range of salinities, from full-strength seawater to completely fresh river water. This allows them to penetrate far up river systems. Bull sharks have been documented over 4,000 kilometers up the Amazon River, in Lake Nicaragua, in the Mississippi River as far north as Illinois, in the Ganges and Brahmaputra rivers of India and Bangladesh, and in the Brisbane River running through the heart of a major Australian city.
This freshwater capability means bull sharks occupy the same warm, shallow, murky waters where humans swim, fish, wade, and bathe -- exactly the conditions in which shark encounters are most likely and visibility is poorest. Many attacks historically attributed to great whites in tropical and subtropical rivers and estuaries were likely committed by bull sharks.
Tiger Sharks: The Ocean's Garbage Disposal
The tiger shark (Galeocerdo cuvier) is named for the dark vertical stripes on its flanks, which fade as the animal matures. Reaching lengths of over 5 meters (16.5 feet), tiger sharks are among the largest predatory sharks and have earned a reputation for eating virtually anything.
The Indiscriminate Diet
Stomach content analyses have revealed an astonishing catalog of items consumed by tiger sharks: sea turtles, seabirds, dolphins, squid, crabs, stingrays, smaller sharks, jellyfish, and an array of inedible human refuse including license plates, tires, pieces of armor, a chicken coop, an unopened can of Spam, and a suit of medieval armor (though the last example, often repeated, appears to be apocryphal). More reliably documented non-food items include nails, boat cushions, oil cans, and plastic bags.
This dietary flexibility is enabled by the tiger shark's broad, heavily serrated teeth, which are shaped like a can opener and capable of shearing through the shells of sea turtles -- one of the few predators capable of doing so. In Hawaii, tiger sharks are recognized as the primary natural predator of green sea turtles and hawksbill turtles, playing a critical role in maintaining turtle population dynamics and grazing patterns on coral reefs.
Mako Sharks: Built for Speed
The shortfin mako (Isurus oxyrinchus) is the fastest shark in the ocean and one of the fastest fish of any kind. Rigorous measurements using accelerometer tags have documented burst speeds of approximately 72 kilometers per hour (45 mph), with some researchers suggesting brief sprints may exceed 80 km/h. This places the mako in the same performance category as blue marlin and yellowfin tuna.
The mako's speed is the product of multiple anatomical refinements: a perfectly streamlined fusiform body, a crescent-shaped tail that generates maximum thrust with minimum drag, and the same rete mirabile heat-exchange system found in great whites, which warms the swimming muscles to peak operating temperature. The mako's skin is covered in tiny, ridged dermal denticles that reduce turbulent drag -- a design so effective that engineers have studied it for application in aircraft and swimsuit design.
Makos are open-ocean predators that feed primarily on fast-moving prey including tuna, swordfish, and other sharks. They are capable of extraordinary vertical leaps when hooked, launching themselves 6 meters (20 feet) or more out of the water -- a behavior that makes them one of the most prized game fish in the world, but also makes them highly vulnerable to overfishing.
Greenland Sharks: The Oldest Vertebrates Alive
The Greenland shark (Somniosus microcephalus) is a sluggish, deep-water species found in the cold waters of the North Atlantic and Arctic Ocean. Reaching lengths of approximately 5 to 7 meters (16 to 23 feet), these sharks swim at an average speed of barely 1.2 kilometers per hour and appear, at first glance, to be among the least remarkable of all sharks.
That impression was overturned dramatically in 2016, when a study published in Science by Julius Nielsen and colleagues at the University of Copenhagen used radiocarbon dating of eye lens proteins to estimate the ages of 28 Greenland sharks. The results were staggering: the largest individual, a 5.02-meter female, was estimated to be approximately 392 years old, with a probability range of 272 to 512 years. This makes the Greenland shark the longest-lived vertebrate ever documented -- an animal potentially born during the reign of Elizabeth I, swimming the same Arctic waters when Shakespeare was writing his plays.
The mechanism behind this extraordinary longevity is not fully understood, but researchers believe the Greenland shark's extremely slow metabolism -- a consequence of living in near-freezing water temperatures of 1 to 12 degrees Celsius -- plays a critical role. Growth rates are estimated at less than 1 centimeter per year, and sexual maturity may not be reached until the animal is approximately 150 years old.
Electroreception: The Sixth Sense
All sharks possess a sensory system that has no equivalent in human experience. The ampullae of Lorenzini -- named after the Italian anatomist Stefano Lorenzini, who first described them in 1678 -- are a network of hundreds to thousands of tiny, gel-filled pores concentrated around the shark's snout, head, and lower jaw.
Each ampulla consists of a surface pore connected to a canal filled with a highly conductive glycoprotein gel, terminating in a cluster of electroreceptor cells. These cells detect the minute electrical fields generated by the muscle contractions and nerve impulses of living organisms. The sensitivity is almost incomprehensibly acute: sharks can detect electrical fields as weak as 5 nanovolts per centimeter -- five billionths of a volt across a single centimeter of water.
To put this in perspective, a flatfish buried beneath 10 centimeters of sand, motionless and invisible, still generates a faint electrical field through the rhythmic contractions of its gill muscles and the beating of its heart. A passing shark can detect this field and pinpoint the prey's location with enough precision to strike accurately on the first attempt. The shark can, in a very literal sense, detect a heartbeat through solid sand.
This electroreceptive system also allows sharks to navigate using the Earth's magnetic field, detect temperature gradients, and possibly sense the electrical fields generated by ocean currents moving through the planet's geomagnetic field -- a form of biological GPS that may explain how sharks navigate across vast, featureless stretches of open ocean.
"No one is afraid of a shark that is 5,000 miles away. The problem is, you never know. Sharks move. They cross oceans. They follow currents and prey in ways we are only beginning to understand. We share this planet with them -- and the ocean is their house, not ours." -- Sylvia Earle, marine biologist and National Geographic Explorer-in-Residence
The Jaws Effect: How One Film Changed Everything
On June 20, 1975, Steven Spielberg's Jaws -- adapted from Peter Benchley's 1974 novel -- opened in American cinemas and fundamentally altered the public perception of sharks. The film was a commercial and cultural phenomenon, becoming the first movie to earn over $100 million at the domestic box office and inventing the concept of the summer blockbuster. It also launched a wave of shark fear and shark killing that lasted decades.
In the years following the film's release, recreational shark fishing tournaments exploded in popularity along the eastern United States. Trophy hunters targeted great whites and other large species with the explicit goal of killing "man-eaters." Great white populations along the northeastern US coast declined measurably during this period. Beaches installed shark nets and drumlines. Municipal governments authorized shark culling programs. The narrative was clear and simple: sharks were monsters, and killing them made people safer.
Peter Benchley, who had written the novel that started it all, spent the last decades of his life trying to undo the damage. He became an outspoken ocean conservationist, wrote extensively about the ecological importance of sharks, and publicly expressed deep regret about the fear his book had generated.
"Knowing what I know now, I could never write that book today. Sharks don't target human beings, and they certainly don't hold grudges." -- Peter Benchley, author of Jaws, in an interview with National Geographic (2000)
Benchley's regret was well-founded. Research conducted in the decades since Jaws has demonstrated that great white sharks do not hunt humans deliberately. Bite-and-release encounters -- in which the shark bites once and immediately disengages -- account for the majority of interactions, suggesting that most "attacks" are cases of investigatory biting by an animal that uses its mouth the way humans use their hands: to determine what an unfamiliar object is.
Shark Comparison Table
| Species | Maximum Length | Maximum Weight | Top Speed | Diet | Notable Feature |
|---|---|---|---|---|---|
| Great White | 6 m (20 ft) | 2,000+ kg (4,400+ lb) | 40 km/h (25 mph) | Marine mammals, fish | Polaris breach ambush hunting |
| Hammerhead (Great) | 6.1 m (20 ft) | 450 kg (990 lb) | 32 km/h (20 mph) | Stingrays, fish, squid | Cephalofoil with 360-degree vision |
| Whale Shark | 12+ m (40+ ft) | 20,000+ kg (44,000+ lb) | 5 km/h (3 mph) | Plankton, fish eggs | Largest fish on Earth, filter feeder |
| Bull Shark | 3.5 m (11.5 ft) | 315 kg (695 lb) | 40 km/h (25 mph) | Fish, dolphins, turtles | Freshwater tolerance |
| Tiger Shark | 5+ m (16.5+ ft) | 635 kg (1,400 lb) | 32 km/h (20 mph) | Almost anything | Sea turtle specialist |
| Shortfin Mako | 4 m (13 ft) | 570 kg (1,260 lb) | 72 km/h (45 mph) | Tuna, swordfish | Fastest shark |
| Greenland Shark | 7 m (23 ft) | 1,400 kg (3,100 lb) | 1.2 km/h (0.8 mph) | Fish, seals, carrion | 400+ year lifespan |
The Shark Finning Crisis
The greatest threat facing sharks today is not pollution, habitat loss, or climate change -- though all of these cause harm. It is the industrial-scale slaughter driven by the demand for shark fin soup. An estimated 100 million sharks are killed by humans each year, with some estimates ranging as high as 273 million. The primary driver is the Asian shark fin market, where a single kilogram of dried shark fin can sell for \(500 to \)1,000 USD or more.
Shark finning is the practice of catching a shark, slicing off its fins -- dorsal, pectoral, and caudal -- and discarding the still-living animal back into the ocean. Unable to swim without its fins, the shark sinks to the bottom and dies slowly from suffocation, blood loss, or predation. The fins represent only 2 to 5% of the shark's total body weight, meaning that up to 98% of the animal is wasted.
The ecological consequences of removing apex predators at this scale are cascading and severe. Research in the northwestern Atlantic documented a direct link between the decline of large shark populations and the collapse of bay scallop fisheries -- with sharks removed, populations of cownose rays (a primary shark prey species) exploded, and the rays consumed scallop beds to commercial extinction. Similar trophic cascades have been documented in coral reef systems, where the removal of reef sharks leads to increases in mesopredator populations, declines in herbivorous fish, and ultimately, algal overgrowth that smothers coral.
International conservation efforts have made progress. The Convention on International Trade in Endangered Species (CITES) has listed multiple shark species under Appendix II protections, and more than 30 countries and territories have established shark sanctuaries where commercial shark fishing is prohibited. The Palau National Marine Sanctuary, established in 2015, protects an ocean area roughly the size of France. In 2013, the European Union banned shark finning by requiring that sharks be landed with their fins naturally attached.
Yet enforcement remains weak across much of the world's oceans, and demand for shark fin products continues, particularly in China, Vietnam, and other Southeast Asian markets. The International Union for Conservation of Nature (IUCN) classifies over one-third of all shark and ray species as threatened with extinction.
The Economics of Shark Tourism
One of the most effective arguments for shark conservation is economic. A dead shark generates a one-time payment from the sale of its fins, meat, and cartilage. A living shark generates revenue year after year through ecotourism.
A comprehensive study published in the journal Oryx estimated that global shark tourism was worth approximately $314 million per year in direct expenditure and supported over 10,000 jobs in 29 countries. The study found that in many locations, a single reef shark was worth over $250,000 in tourism revenue over its lifetime, compared to a one-time value of roughly $108 if killed and sold for its fins and meat.
In the Bahamas, where sharks have been protected since 2011, shark diving tourism generates an estimated $113 million annually and employs over 2,000 people. In Palau, each reef shark is worth approximately $1.9 million over its lifetime in tourism revenue. In South Africa, great white cage diving generates millions in annual revenue for communities along the Western Cape coast.
These figures make a compelling case: sharks are worth more alive than dead, not just ecologically, but financially.
A Future with Sharks
Sharks have survived every catastrophe the planet has thrown at them for 450 million years -- asteroid impacts, volcanic megaeruptions, ice ages, continental rearrangements, and five mass extinctions. They have survived everything except us. The question of whether sharks will persist into the next century is not a question about their evolutionary fitness. They are superb animals, refined by geological time into forms of extraordinary efficiency and elegance. The question is whether humanity will choose to let them survive.
The science is unambiguous. Healthy oceans require healthy shark populations. Sharks regulate prey species from the top down, maintain the structure of marine food webs, and influence the behavior of species at every trophic level through what ecologists call the landscape of fear -- the mere presence of a predator changes how and where prey species feed, rest, and reproduce, shaping entire ecosystems in ways that vanish when the predator is removed.
"We have been looking at the ocean as if it is an inexhaustible resource and sharks as if they are an inexhaustible enemy. Both assumptions are catastrophically wrong." -- Sylvia Earle, Mission Blue documentary (2014)
The path forward requires a combination of stronger international fishing regulations, expanded marine protected areas, reduced consumer demand for shark fin products, and continued investment in shark research and ecotourism economies. It also requires something harder: a fundamental shift in how humans think about sharks. Not as monsters. Not as man-eaters. But as ancient, essential, and increasingly vulnerable inhabitants of an ocean we share.
References
Ferretti, F., Worm, B., Britten, G. L., Heithaus, M. R., & Lotze, H. K. (2010). "Patterns and ecosystem consequences of shark declines in the ocean." Ecology Letters, 13(8), 1055-1071.
Nielsen, J., Hedeholm, R. B., Heinemeier, J., et al. (2016). "Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus)." Science, 353(6300), 702-704.
Cisneros-Montemayor, A. M., Barnes-Mauthe, M., Al-Abdulrazzak, D., Navarro-Holm, E., & Sumaila, U. R. (2013). "Global economic value of shark ecotourism: implications for conservation." Oryx, 47(3), 381-388.
Worm, B., Davis, B., Kettemer, L., et al. (2013). "Global catches, exploitation rates, and rebuilding options for sharks." Marine Policy, 40, 194-204.
McComb, D. M., Tricas, T. C., & Kajiura, S. M. (2009). "Enhanced visual fields in hammerhead sharks." Journal of Experimental Biology, 212(24), 4010-4018.
Kajiura, S. M., & Holland, K. N. (2002). "Electroreception in juvenile scalloped hammerhead and sandbar sharks." Journal of Experimental Biology, 205(23), 3609-3621.
Benchley, P. (2002). Shark Trouble: True Stories About Sharks and the Sea. Random House.
Frequently Asked Questions
How likely is a shark attack, and how many people are killed by sharks each year?
Shark attacks on humans are extraordinarily rare. The International Shark Attack File at the University of Florida records an average of approximately 70 to 80 unprovoked shark attacks worldwide per year, with only about 5 to 10 resulting in fatalities. For perspective, you are far more likely to be killed by a lightning strike, a bee sting, or a falling vending machine than by a shark. Humans kill roughly 100 million sharks annually through fishing and finning, meaning for every human killed by a shark, humans kill approximately 11 to 25 million sharks in return. The species most frequently involved in unprovoked attacks are the great white, bull shark, and tiger shark.
How big do great white sharks actually get?
Great white sharks (Carcharodon carcharias) are among the largest predatory fish on Earth. Reliable measurements place the maximum length of adult females -- which are larger than males -- at approximately 6 meters (20 feet), with weights reaching 2,000 kilograms (4,400 pounds) or more. The largest great white reliably measured was a female named Deep Blue, estimated at approximately 6.1 meters (20 feet) in length. Claims of 7-meter or larger specimens exist historically but lack rigorous scientific verification. Most adult great whites encountered by researchers measure between 3.5 and 5 meters (11.5 to 16.5 feet).
How do sharks detect prey using electroreception?
Sharks possess a sensory system called the ampullae of Lorenzini -- hundreds to thousands of tiny gel-filled pores concentrated around the snout and head. These electroreceptors detect the faint bioelectric fields generated by the muscle contractions and heartbeats of other living organisms. The sensitivity is extraordinary: sharks can detect electrical fields as weak as 5 nanovolts per centimeter, equivalent to detecting a single AA battery from over 1,600 kilometers away. This allows sharks to locate prey buried beneath sand or hidden in murky water where vision is useless. Hammerhead sharks have an especially wide distribution of ampullae across their broad cephalofoil, giving them superior electroreceptive coverage of the seafloor.