10 Common Shark Myths Debunked
1. Sharks Will Target Swimmers, Divers And Surfers
Thanks to the movies, sharks are thought of as ruthless killers targeting any human foolish enough to get in the water. You might find it reassuring to know just a few of over 400 species are considered dangerous, and you're far more likely to be killed by a cow than a shark. There are around 16 shark attacks each year in America, but just one fatality every two years.
The Shark Trust believe the 'monster' image is not one sharks deserve. Instead, they need to be treated with respect, just like all wild animals. Even a typically harmless species like the filter feeding Basking shark can breach clean out of the water, so getting too close would be most unwise.
Whenever humans are bitten, these incidents are high profile due to their traumatic nature, but they are usually the result of an exploratory bite to see if the target would be suitable prey. The number of reported shark bites is relative to the number of people entering the marine environment each year, with increased popularity of ocean-based recreational pursuits and technology allowing people to remain in the water for longer than usual.
You Can't Hide
2. You Can Hide From Sharks Among Jellyfish
In the 2016 thriller The Shallows, the main character finds herself stranded in water with a great white shark determined to eat her. The film follows her efforts to escape from the giant predator, including hiding among a group of jellyfish.
If you ever came face to face with a shark, don't waste your time looking for jellyfish. Sharks have really thick skin covered in tooth-like scales, so stings would be no more than a tickle. The only vulnerable parts are their eyes, but membranes can be lowered to protect them.
If you're heading to the beach this summer, it is extremely unlikely that you will get into a situation that requires outsmarting a shark in the first place. Certain sections of the media will often print sensationalist style shark reports, often posting a picture of a dorsal fin, which more often than not belongs to a dolphin. Facts are often ignored and unnecessary public concern is created. The media should be informing the public of the true facts; the unfounded anxiety they create only serves as a detriment to sharks and their conservation.
Marine Feeding Frenzy Caused By Sardines
3. Sharks Can Smell A Drop Of Human Blood
A swimmer scratches their head and a single drop of blood falls into the water. A few bars of ominous music later, a hungry shark appears to claim their free meal. It's a classic image, but is a shark's sense of smell really that good?
Well, not quite in reality. Sharks do indeed have a highly complex and acute sense of smell. Their highly evolved olfactory organs allow them to detect the blood of potential prey, pheromones from a potential mate or the scent of a predator from a great distance.
For blood to reach the shark's olfactory system it first has to dissolve and travel through the water, which would take more than seconds. As we're not their normal prey, sharks following the scent of blood aren't targeting humans- they're either investigating or, in the case of ocean whitetips and silky sharks, following their instinct to look for thrashing wounded animals.
4. Some Sharks Go Rogue And Get A Taste For Human Flesh
Many films, from Jaws to The Reef, feature a single ‘rogue’ shark as their villain. The book Jaws was written at a time when some people believed that sharks could develop a taste for humans and choose to hunt them instead of their natural prey. This theory has largely been dismissed, but the rogue shark concept continues to prevail in the film industry and is a favorite of film fans. Shark films are a now a niche genre, sitting alongside alien and zombie films.
For a carnivorous shark to switch to a diet of humans would make very little sense at all. Not only are we far less common in the oceans than fish, seals and seabirds, but we also provide much less energy than an insulated animal like a sea lion. Given the low percentage of people who are actually killed in attacks, some scientists even argue that we taste bad to sharks; most bites to humans are exploratory, and the sharks move on when they realize they’ve mistaken a swimmer for a seal.
The Fastest Shark
5. Sharks Leap From The Water To Attack Boats
The glimpse of a fin sliding through the waves, then the huge creature launching itself at people on a beach or a boat- it’s a common theme in movies with sharks as antagonists. Of the hundreds of species, just a few come close enough to the surface to expose their fin, and most people claiming to have seen a great white off the coast off the coast of the UK were actually at a basking shark, dolphin or porpoise.
As for the idea of a shark leaping from the ocean after a human, it’s not something that’s ever been seen in the real world. The great white shark can jump 8 feet out of the water to grab seals and birds, but a boat doesn’t look like prey. It will sometimes wait in the shallows for seals as they head out to sea, but launching onto land is the speciality of the orca.
One shark that does (accidentally) land on boats is the shortfin mako. As well as being the fastest species, this shark is capable of leaping 30 feet above the surface, and these record breaking jumps sometimes put them on a collision course with passing vessels.
The Real Methuselah
6. Sharks Live For Thousands Of Years
Investigating the deaths of the great white’s victims in Jaws, police chief Martin Brody reads that sharks can live for up to 3000 years. He should probably have checked a different book, because no shark species has a lifespan even close to that. Although its been found to live longer than previously thought, the great white shark’s average life is still a modest 70 years long.
It may not meet movie expectations, but one shark does claim the record for longest living vertebrate on the planet. Greenland sharks, residents of the cold waters around the Arctic Circle, have been found with up to 400 years already behind them. It’s thought that their large size combined with the low temperatures they live in result in a slow metabolism and a drastically reduced ageing rate.
These sharks are still something of a mystery; their long lives were only discovered a few years ago, and little is known about what they do with their centuries in the sea.
7. Sharks Have Tongues
As a great white shark launches at its potential victim in Jaws 3-D, a huge pink tongue flaps in its gaping mouth. But while sharks do have something similar to a tongue, it doesn’t look anything like ours.
The shark equivalent of a tongue is called the basihyal, and its something they share with the other bony fish. While four limbed vertebrates have long, flexible tongues used for tasks like manoeuvring food, the basihyal is the front section of a bar of cartilage running from the chest to the mouth. Its primary function is to support the bones associated with the gills, so its pretty rigid.
In a few species, including bullhead and carpet sharks, the basihyal is bigger and more flexible, and it can be teamed with strong throat muscles to help suck prey into the mouth. The cookiecutter shark, a small dogfish shark, makes the best use of its ’tongue’, earning its name by taking cookie-shaped chunks of flesh out of its prey with its sharp teeth and then vacuuming them up.
8. Sharks Can Swim Backwards
Jaws 3-D, the third installment in the Jaws franchise, centers on a pair of great whites that sneak into SeaWorld. In one sequence, the larger shark backs out of a filtration pipe at enough speed to break through the grille trapping it there.
That really should have the end of the story for the man-eating shark, because sharks can’t swim in reverse. They’re propelled by their tails and use their pectoral fins for balance and turning, and their anatomy simply doesn’t allow them to go in any direction other than ahead.
While many sharks are able to pump oxygen rich water through their bodies using their pharynxes as they lie on the seabed, some species- including the great white- lack this ability and have to swim forward constantly to keep water flowing over the gills.
9. Sharks Seek Revenge
The great white shark in Jaws: The Revenge is so determined to wreak havoc on the Brody family that it follows them from the northeast coast of America to the Bahamas. As perfect as it would be for filmmakers, sharks aren’t really capable of holding grudges- their main motivation is always just getting enough to eat.
Sharks are intelligent fish, and its been shown that they’re capable of learning. When tour boats repeatedly feed them they began to associate people with food, but vengeance doesn’t enter their minds.
If sharks were capable of revenge, it would arguably be justified; we’re much more dangerous to them than they are to us. While they kill less than one person a year, in the same amount of time 100 million sharks are killed by humans. Many of these are victims of the shark fin trade, their fins cut off for soup and traditional medicine and their bodies thrown back into the sea, but others are killed in the hope that it will make the oceans safer. Not long after the release of Jaws shark hunting became popular, and in 2014 the Australian Government began a controversial (and short-lived) cull of sharks around the west coast.
The Hunter Without A Roar
10. Sharks Can Roar
As they launch their attacks, sharks in several movies let loose huge lion like roars. The ocean is no stranger to loud noises, from cheery dolphin clicks to haunting whale song, but there’s no risk of ever coming across a roaring shark; they lack the vocal chords needed to produce such a sound. Sharks have evolved bodies for stealth. Not only do they produce no vocalisations, their scales are the ideal shape for sliding silently through the water.
The only exceptions come in the form of the draughtsboard shark and the swell shark. These species quickly force water into their stomachs if they’re threatened, puffing up to several times their normal size in an attempt to deter their assailant. If they’re successful, the sharks relax and the water rushes back out. If fishermen accidentally catch either of these sharks, they gulp air instead of water- they can’t hold on to the air for long, so it gets expelled with a loud bark.
© 2018 James Kenny