Ready for Shark Week? The Most Surprising Facts About Sharks

In a time of such uncertainty, many of us are looking for some semblance of normalcy or routine to cling on to. For many animal lovers or adventure seekers, Discovery Channel's annual Shark Week might be just that thing. The yearly event, which debuted in 1988, is back this year starting August 9 with a week chock full of shark content. Cameras take viewers up close and personal to learn more about one of the most misunderstood creatures of the sea. In honor of Shark Week, we've put together a list of surprising facts and figures about sharks that might challenge your preconceptions.

Whale Shark
Whale sharks swimming at the surface of the ocean in Western Australia off of Ningaloo Reef. Getty/James D. Morgan

Each whale shark's spot pattern is unique as a fingerprint.

Though the image of a large, sharp-toothed great white on the poster for Jaws might be the first thing that comes to mind when thinking about sharks, they come in many shapes and sizes. Whale sharks, which are the largest species of shark as well as one the largest creatures that live in the ocean measuring around 40 feet long. As is the case with human fingerprints, the spotted patterns on the back of each whale shark are unique. Organizations like the World Wildlife Fund can use this to help identify and keep track of the animals.

Not all sharks live in salt water.

Just like how all sharks don't look the same, they also don't all live in the same environments. While the majority of sharks do live in the ocean, some species prefer fresher water, like bow sharks. But there might be a good reason so many sharks prefer salt water, and it can be found in their livers. Unlike many underwater creatures, sharks do not have swim bladders—which help animals with buoyancy. They do have quite large livers that can help a bit with buoyancy, but scientists have found that the composition of salt water is easier for sharks to float in making it a more obvious choice for where they choose to spend their time.

Sharks can be pregnant for over three years and can be impregnated by multiple partners.

Many large animals in the animal kingdom have long gestation periods: Elephants can carry their babies for up to 22 months before giving birth, Walruses for up to 16 months, but some species of sharks will carry their young for over three years. The frilled shark has the longest record and can be pregnant for three-and-a-half years before giving birth. Another difference in sharks reproductive behaviors is it is possible for a female shark to carry the offspring of two mates—at the same time. Though not documented in all species of sharks, it has been found in at least six species in which a single litter of sharks has two, and sometimes more, dads.

Great White Shark
Great White Shark breaching at Seal Island, False Bay, South Africa. Chris Brunskill Ltd/Corbis/Getty

Sharks have a sixth sense.

We all probably know that sharks have a keen sense of smell, especially if that smell is blood, but what might come as a surprise is that they actually have a sixth sense that picks up electric fields given off by animals in surrounding waters. In fact, they are the best electrical sensors on the planet, having more sensitivity to electricity than measuring equipment built to detect such currents. This is also why sharks are able to hunt in dark or murky water. Scientists are also trying to use this feature to help protect sharks against accidents with fishing equipment by developing a system of magnets that could repel sharks from nets and lines.

Shark embryos in eggs can sense danger.

This supercharged skill doesn't just begin after birth, sharks can start detecting these electrical currents from inside an egg. While some sharks have live births, like humans, some sharks lay eggs. As the shark develops and grows inside of the egg, the bottom of the "mermaid's purse," as the sac is called, opens up so the shark can start getting the nutrients from seawater. But, when the sac opens, it does make the undeveloped animal a bit more vulnerable to surrounding predators, which is when the sixth sense comes in. Scientists say the sense develops after the sac opens, which allows the animal to sense the electricity of a possible predator and freeze themselves to not cause a stir.

Hammerhead
Close up of a hammerhead shark exposing its teeth. Discovery Channel

Great white sharks can go weeks without eating.

Great white sharks are probably one of the most famous species of sharks—certainly since Jaws. As the name suggests, these animals are quite big, which means they do require a lot of food to survive—though not as much as you might think. They eat around 11 tons of food of year, but considering one of their favorite foods—a sea lion—weighs more than half a ton, they reach that 11-ton mark pretty quickly. In fact, after a large meal, a great white shark can go up to three months without consuming another meal.

Galeophobia is the excessive fear of sharks.

People have phobias of all sorts of things, and one phobia that is not so surprising is the intense fear of sharks dubbed Galeophobia. In 1975, when Steven Spielberg released Jaws, audiences around the world were given an up-close look at the potential dangers of sharks—leaving many scared to enter the water. Due in part to the portrayal of the shark in the film—a creatures out for the blood of humans—shark populations declined in the years following the release of the film, also because of overfishing. In recent weeks, though, great whites have come back into our collective consciousness as reports of numerous shark attacks have popped up off the coast of beaches in the northeast United States.

Shark fishing
A shortfin mako shark emerges from the water after being caught by Eric Kelly on the Kalida during the 31st North Atlantic Monster Shark Tournament on July 14, 2017 in New Bedford, Massachusetts. Maddie Meyer/Getty

Humans kill sharks far more often than sharks kill humans.

In 2019, just two people were killed as the result of a shark attack and the amount of total unprovoked shark attacks was down to 64 from an average of 82. Both fatal shark attacks happened outside of the United States, one near Reunion Island and the other in the Bahamas. The majority of attacks, however, do happen in the U.S. Conversely, humans kill about 100 million sharks per year on average worldwide. The odds of being attacked by a shark and in turn killed by a shark are so slim—you are more likely to be killed by a wasp or dog than you are a shark. With that in mind, though, keep a lookout for shark sightings and always respect local guidelines for swimming at a beach.

A shark's life span is much longer than previously believed.

For years, scientists have estimated that the average life span of sharks is roughly 30 years. The most widely used way of determining a shark's age is by counting bands on the animal's vertebrae. Newer techniques, however, might lead to a more accurate reading on shark's ages. One study found that Greenland sharks can live for more than three centuries. The great white shark and sand sharks are two other species whose life spans have likely been underestimated.

Air Jaws
First ever breaching great white shark recorded in New Zealand. Discovery Channel

Sharks are unable to make audible noise.

Over 400 species of sharks exist, and not one of them has the ability to make sound—at least an audible one. They do not have the ability to make sound the way humans do, or more relatively, the way whales do. Dory, in Finding Nemo famously claims she can speak whale, which is the sound we all might associate with the sound a whale makes, but there is no such sound associated with a shark.

Sharks can live in volcanoes.

Yup, you read that right. In 2015, scientists discovered sharks swimming around one of the most active underwater volcanoes in the world, which should only really be hospitable to microscopic organisms. They were spotted not long after an eruption which stumped scientists. The volcano, Kavachi, is located near the Solomon Islands in the southwest Pacific ocean. Given the nature of the location, it is hard to study in person so scientists sent down robots to get a closer look. Sharkcano, which is part of Nat Geo's Sharkfest, chronicles scientists' journeys to various underwater volcanoes to study the sharks' behavior further.