The human fear of sharks has deep roots. Written works and art from the ancient world contain references to sharks preying on sailors as early as the eighth century BC
Returned to land, stories of shark encounters have been embellished and amplified. Coupled with the fact that sharks bite humans from time to time – very rarely – people have been prepared for centuries to imagine terrifying situations at sea.
In 1974, Peter Benchley‘s bestselling novel “Jaws” fueled this fear into a wildfire that spread across the world. The book sold more than 5 million copies in the US within a year and was quickly followed by Steven Spielberg’s 1975 film, which became the highest-grossing film in history at the time. Nearly all viewers embraced the idea, vividly depicted in the film and its sequels, that sharks were vicious, vengeful creatures that prowled coastal waters in search of food for unsuspecting swimmers.
But ‘Jaws’ also sparked widespread interest in better understanding sharks.
Previously, shark research was largely the esoteric domain of a handful of academic specialists. Thanks to the interest sparked by “Jaws,” we now know that there are many more species of sharks than scientists knew in 1974, and that sharks do more interesting things than researchers ever expected. Benchley himself became an ardent spokesperson for shark protection and marine conservation.
In my thirty-year career studying sharks and their close relatives, rays and rays, I have seen attitudes evolve and interest in understanding sharks increase dramatically. Here’s how things have changed.
Swimming in the spotlight
Before the mid-1970s, much of what was known about sharks came from people going to sea. In 1958, the U.S. Navy established the International Shark Attack File – the world’s only scientifically documented, comprehensive database of all known shark attacks – to reduce war risks to sailors stranded at sea when their ships sank.
Today the stock is managed by the Florida Museum of Natural History and the American Elasmobranch Society, a professional organization for shark researchers. It works to educate the public about shark-human interactions and ways to reduce the risk of shark bites.
In 1962, Jack Casey, a pioneer in modern shark research, started the Cooperative Shark Tagging Program. This initiative, which is still ongoing, relied on commercial fishermen from the Atlantic Ocean to report and return the tags they found on sharks so that government scientists could calculate how far the sharks had moved after being tagged.
After “Jaws,” shark research quickly went mainstream. The American Elasmobranch Society was founded in 1982. Graduate students lined up to study shark behavior, and the number of published shark studies increased sharply.
Field research on sharks expanded in parallel with the growing interest in extreme outdoor sports such as surfing, parasailing and diving. Electronic tags allowed researchers to track sharks’ movements in real time. DNA sequencing technologies provided cost-effective ways to determine how different species were related to each other, what they ate, and how populations were structured.
This interest also had a sensational side, as epitomized by the Discovery Channel’s launch of Shark Week in 1988. Ostensibly intended to educate the public about shark biology and counter negative publicity about sharks, this annual block of programming was a commercial venture that exploited the tension between people’s deep-seated fear of sharks and their desire to understand what made these animals tick.
Shark Week featured made-for-TV stories that focused on fictional scientific research projects. It was hugely successful and remains so, despite criticism from some researchers who call it a major source of misinformation about sharks and shark science.
Physical, social and genetic insights
Contrary to the long-standing idea that sharks are mindless killers, they exhibit a wide range of traits and behaviors. The velvet belly lantern shark, for example, communicates via flashes of light from organs on the sides of its body. Female hammerhead sharks can clone perfect replicas of themselves without male sperm.
Sharks have the most sensitive electrical detectors yet discovered in nature: networks of pores and nerves in their heads known as ampullae of Lorenzini, after the Italian scientist Stefano Lorenzini, who first described these features in the 17th century. Sharks use these networks to navigate in the open ocean, using the Earth’s magnetic field for orientation.
Another intriguing discovery is that some shark species, including makos and blue sharks, segregate based on both gender and size. Among these species, cohorts of males and females of different sizes are often found in different groups. This finding suggests that some sharks may have social hierarchies, such as those found in some primates and hoofed mammals.
Genetic studies have helped researchers explore questions such as why some sharks have heads shaped like hammers or shovels. They also show that sharks have the lowest mutation rate of all vertebrates. This is remarkable because mutations are the raw material for evolution: the higher the mutation rate, the better a species can adapt to environmental changes.
However, sharks have been around for 400 million years and have experienced some of the most extreme environmental changes on Earth. It is not yet known how they managed to survive so successfully with such a low mutation rate.
The tent kind
White sharks, the main species of ‘Jaws’, attract enormous public interest, although much about them is still unknown. They can live up to 70 years and routinely swim thousands of miles per year. Those in the western North Atlantic tend to move north to south between Canada and the Gulf of Mexico; white sharks on the west coast of the US move east to west between California and the central Pacific Ocean.
We now know that young white sharks feed almost exclusively on fish and stingrays, and do not begin to include seals and other marine mammals in their diet until they are the equivalent of teenagers and have grown to about 3 meters in length. Most confirmed white shark bites on humans appear to come from animals between 3 and 5 meters in length. This supports the theory that almost all white shark bites on humans are cases of mistaken identity, with humans resembling the seals that sharks prey on.
Still in the water
Although “Jaws” had a widespread cultural impact, it didn’t stop surfers and swimmers from enjoying the ocean.
Data from the International Shark Attack File on confirmed unprovoked bites by white sharks from the 1960s to the present shows a continued increase, although the number of incidents per year is quite low. This pattern is consistent with the growing number of people engaging in recreational activities on the coast.
Worldwide, there have been 363 confirmed unprovoked bites by white sharks since 1960. Of these, 73 were fatal. The World Health Organization estimates that 236,000 deaths occur annually due to drowning, which equates to approximately 15 million drowning deaths in the same period.
In other words, people are roughly 200,000 times more likely to drown than to die from a white shark bite. Indeed, surfers are more likely to die in a car accident on the way to the beach than be bitten by a shark.
This article is republished from The Conversation, a nonprofit, independent news organization providing facts and analysis to help you understand our complex world.
It was written by: Gavin Naylor, University of Florida.
Gavin Naylor receives funding from the National Science Foundation and the Lenfest Foundation.