In the last 80 years, more than 70 “killer shark” films have been produced, reinforcing the myth of deadly monsters of the deep. But how much do we really know about these animals? Test your knowledge and learn some interesting facts about sharks.
Among popular culture and frightening news stories, shark facts can get lost in the fiction. For an animal whose fossil records date back over 400 million years, little is widely understood about the more than 500 shark species alive today. Even Peter Benchley, the author of Jaws, regrets the part his work played in villainizing the animals. “Knowing what I know now, I could never write that book today,” Benchley said. So what’s true about sharks and what’s just fuel for the next terrifying movie trailer?
Contrary to the popular belief of beachgoers who grew up with John Williams’s menacing soundtrack pulsing through their imagination, sharks do not hunt humans. The actual risk of ever being bitten by a shark is nearly nonexistent. You have a better chance of being struck by lightning, killed by a falling coconut, killed by hippos, killed by cows, or bitten by a human in New York City than you are to be bitten by a shark. Even mosquitos kill more people in one day – through carrying and transmitting diseases – than sharks have killed over the last 100 years worldwide.
When sharks do take a bite (most injuries are from a single nip), they realize that the human is not food and move on. Researchers at California State University, Long Beach conducted a 2-year study of great white sharks off the coast of Southern California to document how often sharks and humans come into close proximity. Over the course of the study, there was just one unofficial report of a white shark bite, but researchers documented human-shark interaction on 97% of the days they observed, demonstrating that shark encounters are common and not particularly dangerous. According to the American Museum of Natural History, over 75% of all shark species will almost never encounter a human being and/or are incapable of consuming a human.
Recent research does indicate shark attacks on humans in some parts of the world are on the rise, but scientists attribute the increase is due to the rise in populations of humans and fur seals along the coastlines (the seals are a favorite meal for great white sharks), as well as shifts in where sharks congregate to search for food due to the climate crisis.
Sharks can smell. But not all sharks smell in the same way. Some sharks can sense how concentrated a substance is in the water and follow it to the source, others must follow the current and rely more on their visual acuity. And while sharks can smell, they can’t smell blood from miles away. More compelling science suggests that acoustics can signal sharks from considerable distances. Sharks have pit organs over their body that serve as distance touch receptors, responding to displacement produced by sound waves as low as 800 hertz. Sharks also use electroreception at short distances to direct a shark toward live prey just before they strike.
The idea that sharks are deadly shadows terrorizing the oceans unchecked may make for a tantalizing movie pitch, but it is entirely inaccurate. While sharks are apex predators who are essential to maintaining the natural balance of marine ecosystems, they are not invulnerable.
Orcas or Killer Whales have been known to hunt sharks, eating species like the mako and even the great white shark by flipping them over to stun them. But sharks’ most dangerous predator is human beings. Through intentional and unintentional fishing practices, millions of sharks are killed annually. Open ocean fishing targeting tuna and billfishes can also hook sharks. While some bycatch is released alive or discarded, in some regions of the world sharks are an important source of income for fishers. The demand for shark meat, leather, liver oil, cartilage, and fins is the biggest threat to global shark populations. Finning is the most concerning practice, as the demand for expensive shark fin soup is a lucrative market. Shark fins can bring in up to $1,313 per pound. 73 million sharks are killed for their fins each year.
In Hong Kong, the center of the shark fin trade, shark fin soup is served at wedding banquets and other celebrations. But while traditional beliefs attribute good fortune and health to shark fin soup, the fins offer no nutritional value and due to the prey sharks hunt, actually contain mercury which can severely affect your health. Worse, the brutal fishing for shark fins ends with the shark tossed back into the water, still alive. Sharks cannot swim effectively without their fin and sink to the bottom of the ocean where they suffocate or are eaten by other predators.
Another interesting fact about sharks is they were once thought to be able to cure cancer. In the 1970s, research at the John Hopkins School of Medicine, Baltimore, recorded shark cartilage preventing new blood vessels from growing into tissues—a characteristic of malignant tumors—which ignited a boon of study into the connection. However, contrary to the evidence collected in the 70s, it’s been known for over 150 years that sharks can get cancer. Regardless, the craze for “cancer-killing” shark cartilage has decimated shark populations. According to Scientific American, North American shark populations have decreased by up to 80% in the last decade.
While the apex predator that has to keep moving to survive is a great metaphor for the business boardroom, it’s not entirely accurate regarding real sharks. Some sharks do need to be continuously moving to keep oxygen-rich water flowing over their gills, but others can pass water through their respiratory system with the help of their muscles. The zebra shark and the nurse shark can hang nearly still in the water and breath by using a pumping motion through oral muscles.
With so many species of sharks, there is a full spectrum of sizes, from the whale shark that can grow up to 59 feet to the dwarf lantern shark which can only grow to 7.5 inches and fits in the palm of your hand. Both the whale shark and the slightly smaller basking shark only feed on fish eggs and other tiny organisms, hardly the diet of a sea monster.
As apex predators, sharks not only maintain ocean order, they act as an indicator for ocean health by indirectly culling the weak and sick and protecting sea life diversity by preserving the balance with other competitors. As they linger in one hunting ground, their prey’s spatial habitat shifts and alters the feeding and diets of other species, maintaining seagrass and coral reef habitats. A decrease in shark numbers corresponds with decreases in coral reefs, seagrass beds, and loss of commercial fisheries.
Indirectly, sharks’ management of the food chain affects the economy. An example of the checks and balances instituted by sharks was documented in a North Carolina study where the loss of sharks caused the ray population to explode. Consequently, all the bay scallops and other bivalves were devoured by the hungry rays, closing a fishery and wiping the American staple of clam chowder off many restaurant menus. Sharks also influence ecotourism. A single reef shark is worth $1.9 million through dive tourism compared to the one-time value of $108 when fished. A whale shark in Belize can earn more than $2 million in its lifetime through ecotourism.
Sharks also help keep carbon out of the atmosphere. Without deep-sea sharks that eat and scavenge dead animals on the ocean floor, it’s estimated that the manufactured carbon in the atmosphere would double!
Sharks have lived through all five mass extinction events so the species itself is ancient. The oldest living vertebrate is a Greenland shark, nearly 400 years old, that swam the ocean at the same time as the Mayflower ship brought colonists to North America. The great hammerhead shark is on the shorter end of the shark lifespan scale, living about 44 years. Far on the other side of the scale, the average age of Greenland sharks is 272 years.
The ravenous rate of shark fishing is underpinned by the slow growth cycle of sharks. Sharks produce relatively few young and take many years to mature, making it impossible to replenish populations at the same rate they are hunted. As a result, a quarter of the world’s shark species (130/520) are threatened with extinction. Through overfishing, habitat destruction, gill netting, trophies and sport fishing, and other human activities, people kill about 100 million sharks every year. Populations are estimated to have declined by 71% since 1970. Fisheries scientists estimate that only 1 in every 10 large fish remains in the ocean.
From the language you use when you talk about sharks to supporting causes that work to protect these important animals, there are many ways to help save sharks. Words matter and can enforce or disarm bias towards these misunderstood creatures. Most interactions between people and sharks are cases of mistaken identity, hardly any incident can be called an “attack.” And there’s no such thing as “shark-infested waters”—they just live there!
Many conservation projects work to dispel misconceptions and work to protect sharks. Supporting projects like Save Our Sharks and The Ocean Before It’s Too Late by Action Change which organizes long-term sustainable research and awareness campaigns through local initiatives will equip communities with the tools they need to fully participate in marine conservation. GVI Charitable Programs works with local partners to maintain the Curieuse Island National Park in Seychelles and the Mesoamerican Barrier Reef in the Caribbean. Your support empowers community-led projects that protect threatened species including sharks.
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