Why Do Sharks Attack Humans? Understanding Shark Behavior

Shark attacks on humans are incredibly rare, but they captivate public fascination whenever they occur. With an average of only about 75 unprovoked shark attacks happening worldwide each year, the chances of getting bitten by a shark are extremely low. However, understanding what motivates sharks to bite humans on those rare occasions can help people stay safer in the water.

When a shark does attack a human, there are usually specific reasons behind it. Sharks rely on their sensitive mouths to investigate their surroundings, so most bites occur out of curiosity or confusion, not a desire to eat humans. By learning more about these reasons and the shark species most dangerous to humans, we can better coexist with these apex ocean predators.

Curiosity Drives Sharks to Bite Humans

One of the most common motivations for a shark bite is curiosity. Sharks don't have hands, so they use their mouths to touch, taste, and examine anything unfamiliar in their environment. When sharks encounter humans in the ocean, they likely want to understand what we are, not eat us.

"Sharks have been known to attack humans when they are confused or curious. If a shark sees a human splashing in the water, it may try to investigate, leading to an accidental attack," says marine biologist John Smith.

Their bites allows them to gather information about us, like our size, texture, and whether we'd make a suitable prey animal. Sharks have an extremely sensitive sense of touch thanks to the abundance of nerve endings in their snouts and teeth. Their investigatory bites are not meant to be aggressive, but rather just a way to satiate curiosity about an unfamiliar animal.

Confusion Causes Accidental Shark Bites

In some cases, a shark doesn't even realize that it's biting a human. When we splash around near sharks, it can confuse them into thinking we are a prey animal like a seal.

"Some sharks may bite humans to assess whether it's worth eating them. Their gums and slightly mobile teeth are so sensitive that they can gauge the probable fat content of a potential prey item. Humans fall far short of the blubbery BMIs of seals and sea lions, so such encounters likely result from sharks actively assessing whether it's worth eating a human, not actually trying to eat one," Smith explains.

If a shark sees a human swimming or surfing, it may take an exploratory bite to figure out what we are. When the shark realizes the human is not its normal food source, it will likely release and swim away. While these bites are accidental, they can still cause serious injury to humans.

Maternal Instinct Drives Shark Bites

One of the only times a shark might aggressively attack a human is when it feels its young are being threatened. Female sharks have strong maternal instincts and may bite humans who get too close to their pups.

"Female sharks may attack humans if they feel their young are threatened," says Smith.

Since female sharks return to the same nursery sites every year to give birth, these areas often overlap with human recreation and fishing. If a female shark interprets human activity as a threat, she may attack to protect her offspring. These defensive bites are less common than curiosity or confusion bites but can be more dangerous due to the shark's aggressive motivation.

The Shark Species Most Dangerous to Humans

While most shark species are not considered dangerous to humans, there are a handful of sharks responsible for a majority of bites and fatal attacks on people. These species share traits like large size, speed, abundance near humans, and aggressive feeding behaviors. Here are the shark species experts consider most dangerous:

Great White Sharks

The great white shark is the largest predatory shark and accounts for the most shark attack fatalities worldwide. Its size, power, and distribution make it an apex ocean predator.

"The great white shark is responsible for almost half of all shark attacks per year and has been recorded to kill roughly 52 humans and a total of 333 official attacks," says Smith.

Great whites can reach lengths over 20 feet and weigh up to 5,000 pounds. They have pointed snouts, sharp triangular teeth, and powerful jaws. Their bodies are gray on top and white below with dark fin tips. Found in coastal waters across the globe, great white sharks may attack humans due to curiosity or confusion.

Tiger Sharks

After great whites, tiger sharks are responsible for the second-highest number of shark bites on humans. They are large, voracious sharks found in tropical and subtropical waters worldwide.

"According to the International Shark Attack File, the tiger shark ranks No. 2 behind the white shark in the number of reported attacks on humans. The shark-monitoring group notes that the animal's 'large size and voraciousness' qualify it as a formidable ocean predator. Surfers and swimmers need to know that tiger sharks tend to be both curious and aggressive when they spot humans in the water," says Smith.

Tiger sharks have blunt snouts, extremely sharp teeth, and muscular bodies that can reach 18 feet long and weigh over 1,400 pounds. They are named for their dark stripes and spots that fade as they age. Abundant off beaches, tiger sharks will bite humans out of curiosity or confusion, but also exhibit more predatory behavior than other sharks.

Bull Sharks

Bull sharks are aggressive apex predators found in coastal tropical and subtropical waters around the world. They are known to swim up rivers and estuaries, making them more likely to encounter humans.

"Bull sharks are considered to be some of the most dangerous shark species to humans for several reasons. They are known to be aggressive and often attack without warning. Secondly, they have a powerful bite that can cause serious injury or death. They also inhabit coastal waters where people often swim and surf, making them more likely to come into contact with humans," says Smith.

With thick bodies up to 11 feet long, bull sharks have a short, blunt snout and tend to headbutt prey before attacking. They earned their name from their stocky shape and short temper. Their aggressive nature and abundance in shallow waters lead to many bites on humans.

Shortfin Mako Sharks

The speedy shortfin mako is the fastest shark species, capable of reaching speeds over 40 miles per hour. Their speed makes them dangerous when tangled in fishing gear or attracted to speared fish.

"Powerful, fast, and aggressive, the shortfin mako has been blamed for many reported shark attacks on humans. In more than a few cases, fisherman have been known to get injured after dragging hooked makos into their boats. The popularity of mako meat in shark fin soup has reduced their populations," Smith explains.

Reaching up to 13 feet long, shortfin makos have a pointed snout, torpedo-shaped body, and razor-sharp teeth. Their speed and large size allow them to inflict serious injury unintentionally when caught by fishermen. They are abundant in temperate and tropical waters worldwide.

Oceanic Whitetip Sharks

While not the most aggressive species, oceanic whitetips are involved in many shark bites due to their widespread distribution in tropical waters. Their unique camouflage makes them stealthy hunters.

"The oceanic whitetip is a large, slow-moving shark that is virtually undetected by its prey due to its ability to become buoyant, swallowing large amounts of air, and rendering them motionless while hunting. It is responsible for several fatal attacks on humans," says Smith.

Growing up to 13 feet long, oceanic whitetips have distinctive rounded first dorsal and pectoral fins. They are bronze to grey with white tips on their fins. Due to their abundance near human recreation, they are likely to bite out of curiosity and confusion.

Key Physical Traits Make Sharks Dangerous

The shark species most dangerous to humans share common physical characteristics that make them effective hunters, including:

  • Sharp Teeth¬†- Serrated, pointed teeth that can cause deep lacerations.

  • Powerful Jaws¬†- Strong bite force that allows them to hold onto prey.

  • Camouflage¬†- Countershading that lets them blend into the ocean.

  • Speed¬†- Ability to accelerate rapidly to capture prey.

These adaptations make these sharks successful apex predators, but also contribute to their potential risk to humans. However, it is critical to remember that sharks do not prefer to feed on humans, and bites occur mostly out of mistaken identity.

Sharks Are Essential Ocean Predators

Despite sensational media coverage of shark attacks, it is important to remember that sharks play a vital role in maintaining healthy ocean ecosystems. As apex predators, they help regulate food chain dynamics and balance marine populations.

Sharks are also highly vulnerable to overfishing due to their slow growth, late maturity, and low reproduction rates. Over 100 million sharks are killed annually by commercial fishing and the shark fin trade. One quarter of shark and ray species are now threatened with extinction, according to Smith.

While a small number of shark species are potentially dangerous to humans, continued conservation efforts are critical to prevent further depletion of global shark populations.

Staying Safe in Shark Habitat

The good news about shark attacks is that they are extremely rare, despite our fear of these apex ocean predators. By understanding what motivates sharks to bite, we can take precautions to reduce the risk when spending time in the ocean.

Here are some tips from experts for staying safe around sharks:

  • Avoid swimming at dawn, dusk or night when sharks are most active.

  • Do not enter the water if you are bleeding from an open wound.

  • Avoid wearing shiny jewelry that could mimic fish scales.

  • Don't swim near people fishing or near fishermen cleaning catches.

  • Avoid murky waters and steep drop-offs where sharks may lurk.

  • Do not harass or provoke sharks if you see them.

  • Follow all warning signs or flags at beaches about shark sightings.

Understanding shark behavior leads to safer interactions for both people and sharks. While shark bites are scary, they are exceedingly rare events. We can enjoy the ocean we share with these apex predators by giving them space and respecting their role in marine ecosystems.