11 Facts About Bull Sharks

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Compared to sharks like the hammerhead (with its oddly shaped skull) and the goblin (with its projectile mouth), the bull shark (Carcharhinus leucas) looks rather generic—but this predator can swim thousands of miles upriver, hunt baby hippos, and take over the occasional golf course.

1. BULL SHARKS HAVE A VERY STRONG BITE.

In 2012, scientists compared the bite strengths of 13 different sharks and shark-like fish and found that an adult bull shark can theoretically close its jaws with just under 6000 newtons of force at the back of its mouth and over 2000 newtons at the front. (Humans chomp with a maximum force of around 900 to 1300 newtons.) So proportionately, the bull shark has the strongest bite of any shark whose jaw strength has been measured. Nobody knows exactly why the shark evolved such a powerful mouth, but it may have something to do with its diet: Bull sharks eat everything from oysters to turtles to other bull sharks, and their herculean jaws might make it easier to tear through a wide range of shells, scales, and skins.

2. THEY THRIVE IN FRESH WATER.

All organisms need a specific salt-to-water ratio within their bodies. This presents a challenge to aquatic life forms—when they absorb too much salt, their cells get dehydrated, but if they take in too much fresh water, the cells get bloated and some of the chemicals inside their bodies may become fatally diluted.

Fish have evolved a couple of tricks to cope with the problem, one of which involves pee. Excess salt is removed from the bloodstreams of oceangoing fish by the kidneys and then flushed out during the urination process. Freshwater fish do the opposite: Their pee contains very little salt and their bodies retain a higher concentration of the substance.

Most fish have no control over how much salt gets removed by their kidneys, which is one reason why many species can only survive in either fresh or salt water. But bull sharks can actually regulate the amount of salt that goes into their pee, which means they can live in both environments. When they swim in the ocean, their urine is highly saline. And as they venture into fresh water, the kidneys work hard to retain salt—thus producing watery, diluted urine. (Bull sharks also use their rectal glands and livers to maintain the proper balance between salt and water.)

3. A BULL SHARK WAS ONCE CAUGHT NEAR ALTON, ILLINOIS.

In 1937, two fishermen captured a 5-foot bull shark more than a thousand miles up the Mississippi River—as far north as this species is known to travel up that river. Given their high tolerance for fresh water, it’s no wonder that bull sharks do well in river systems. One specimen was found swimming in the Amazon River about 2485 miles away from the ocean; they also frequent Africa’s Zambezi River and the Ganges River in south Asia.

4. NOT EVEN HIPPOS ARE SAFE FROM BULL SHARK ATTACKS.

In their trips upriver, bull sharks encounter some of the fiercest predators on earth: In Australia, an 18-foot-long saltwater crocodile named Brutus was once photographed devouring a small bull shark, and in African waterways the sharks have run-ins with hippos. The mammals generate a lot of poop, which attracts small fish that bull sharks eat—so it’s not at all uncommon to see a bull shark or two creeping around a pod of hippos.

The two species don’t always get along. Bull sharks do prey on young hippos on occasion, and adults are sometimes bitten as well—though these attacks might be accidental (in murky, poop-filled water, bull sharks probably mistake hippo legs for fish). Whatever the case may be, large hippopotamuses are adept at fending off bull sharks.

5. UNLIKE GREAT WHITES, BULLS CAN DO WELL IN AQUARIUMS.

No one has been able to keep a great white in captivity for much longer than six months. Bull sharks, however, can live in captivity for 25 years or more. In North America, you can see them at the Oklahoma Aquarium, which houses 10 bull sharks in a nearly 500,000-gallon tank.

6. LAKE NICARAGUA’S RESIDENT BULL SHARKS WERE ONCE THOUGHT TO CONSTITUTE A NEW SPECIES.

Scientists used to think that the large-bodied sharks that periodically attack locals in Lake Nicaragua—the biggest lake in Central America—represented their own, distinct species. A popular hypothesis claimed that Lake Nicaragua must have started out as a bay in the Pacific Ocean that closed up as time went by, trapping some sharks inside that evolved into a brand new species—the so-called “Lake Nicaragua shark,” which ichthyologists called Carcharhinus nicaraguensis.

But Lake Nicaragua isn't cut off from the ocean at all, and scientists eventually determined that “Lake Nicaragua Sharks” are really just bull sharks that were entering the Rio San Juan from the Caribbean and making their way to the lake [PDF].

7. AN AUSTRALIAN GOLF COURSE IS INFESTED WITH THEM.

At the Carbrook Golf Club, located near Brisbane, Australia, tee time sometimes comes with teeth. The course is next to the Logan River, which flooded several times in the 1990s. At some point, newborn bull sharks were probably swept into the brackish, landlocked lake that sits beside tees 12 through 15, and were trapped there when the Logan receded. The lake is spacious (about 50 acres, or the size of Grand Central Terminal) and stocked with fish—good news for the sharks.

The first shark fin sightings were quickly dismissed. “Our members have a tendency to drink a little bit while they play so we really just put that down to too much alcohol,” general manager Scott Wagstaff told National Geographic. But by 2003, there were photos, and a 2011 YouTube video taken by Wagstaff went viral. According to the club’s website, “there are between 6 and 12 sharks” in the lake; the biggest is roughly 9 feet long. It’s also likely that they are breeding.

Carbrook Golf Club celebrates their cartilaginous guests: “Shark Lake Challenge” tournaments are held on the last Wednesday of every month and a stylized shark fin adorns the club logo. For obvious reasons, ball retrieval has been prohibited.

8. BITING IS A PART OF MATING.

Male bull sharks become sexually active at 14 or 15, but females don’t start reproducing until they're 18. Female bull sharks of reproductive age have scars behind their skulls: A male bites his partner to hang on during coitus (a behavior that appears to be common), then uses one of his claspers—a pair of fin extensions located under the pelvic area—to insert sperm into her cloaca.

Following a 10- to 11-month gestation period, the female will give birth to a litter of pups. Newborns typically range between 22 and 32 inches long.

9. ONLY TWO OTHER SHARK SPECIES BITE HUMANS MORE OFTEN.

All types of shark-on-human attacks are ultra-rare—you’re more likely to get struck by lightning. But the three shark species that are most commonly implicated in attacks on people are, in order, the great white shark, the tiger shark, and the bull shark. Bull sharks have been involved in at least 100 documented cases, and there's an explanation for that: They frequent shallow, coastal waters in tropical regions and often stray into brackish and fresh water—all places where humans can be found. In areas where the sharks can’t see very well, they may mistake humans for other, meatier prey.

Since bull sharks lack eye-catching markings or facial features, it can be difficult to identify them. This is why some experts wonder if bull sharks might have been responsible for certain attacks that were blamed on great whites, Ganges river sharks (Glyphis gangeticus), or other species.

10. A BULL SHARK MAY HAVE PARTICIPATED IN THE FAMOUS NEW JERSEY SHARK ATTACKS OF 1916.

On July 1, 1916, a 25-year-old swimmer was bitten by a shark off the coast of New Jersey's Long Beach Island. Though a lifeguard managed to rescue him, the man died of blood loss. Five days later, a bell captain lost both legs in a shark attack near Spring Lake. He too died. Farther north, a boy and an adult man were killed by a shark in Matawan Creek on July 12. Within 30 minutes, a teenager was bitten less than a mile downstream, but he survived.

All five attacks have historically been pinned on a single 8-foot-long great white that was captured and killed on July 14 in Raritan Bay, just a few miles away from the Matawan attacks. Inside its stomach were human remains. No subsequent shark attacks were reported in New Jersey that summer.

But the situation might not be so clear-cut: The two Matawan Creek incidents occurred 11 miles from the ocean, and great whites don't travel to shallow inland waters. Bulls are also more abundant off the Jersey shore than great white sharks are. That leads some experts, including explorer Fabien Cousteau, to conclude that a bull shark was the real culprit. Shark attack expert George Burgess still thinks the evidence points to the great white with a bellyful of body parts. It’s also possible that more than one shark committed the 1916 attacks.

11. NO, BULL SHARKS DON’T HAVE THE ANIMAL KINGDOM’S HIGHEST TESTOSTERONE LEVELS.

According to the internet, some books, and Grand Theft Auto, bull sharks are extra-aggressive because they have more testosterone than any other animal. In reality, very little research has been done on the subject of bull shark hormones. One study compared the testosterone levels in three bull sharks: The female had a low testosterone level (0.1 nanograms per milliliter), one of the males had only 2.7 nanograms per milliliter, and the other male had a ludicrously high testosterone level of 358 nanograms per milliliter—so the results were inconclusive. Bonnethead sharks and rainbow trout both have extreme testosterone levels, so in that regard, bull sharks aren’t special. At least they can still brag about their jaws.

11 Lesser-Known Animal Phobias

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iStock.com/Scacciamosche

He’s dealt with elaborate booby traps, KGB agents, and a face-melting artifact, but to Indiana Jones, nothing’s more unsettling than snakes. Many people can relate. Ophidiophobia—or “the persistent and irrational fear of snakes”—affects roughly 1 to 5 percent of the global population. So does the clinical fear of spiders, also known as arachnophobia. But did you know that some people feel just as uncomfortable around chickens? From puppy-induced panic to equine terror, here are 11 lesser-known animal phobias.

1. Lepidopterophobia

Academy Award-winner Nicole Kidman is unfazed by spiders or snakes, but she can’t escape her lepidopterophobia, or fear of butterflies. As a young girl, the Australian actress once scaled a fence just so she could avoid a butterfly perched nearby. “I jump out of planes, I could be covered in cockroaches, I do all sorts of things,” Kidman once said, “but I just don’t like the feel of butterflies’ bodies.” (The Independent reported that she tried to break her phobia by spending time in a museum butterfly cage. “It didn’t work,” the actress said.) Kidman and her fellow lepidopterophobes may refuse to leave windows open in the summertime, lest a stray monarch come fluttering into their home.

2. Batrachophobia

A giant river toad
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No, frogs can’t give you warts. That urban legend—and others like it—may explain some cases of batrachophobia, a deep-seated fear of amphibians, including frogs, toads, and salamanders. It’s thought that the condition might also be linked to an overarching disdain for slimy things. By the way, if you specifically don’t like toads, then you could have a case of what’s known as bufonophobia.

3. Entomophobia

Entomophobia is a family of fears related to insects that includes lepidopterophobia, the previously mentioned butterfly-related dread. Another phobia within this group is isopterophobia, the fear of wood-eating insects like termites. Then we have myrmecophobia (the fear of ants) and apiphobia (the fear of bees or bee stings). Of course we can’t leave out katsaridaphobia, or the debilitating fear of cockroaches. “Cockroaches tap into this sort of evolutionary aversion we have to greasy, smelly, slimy things,” Jeff Lockwood, an author and professor of natural sciences at the University of Wyoming, told the BBC. “Plus, they’re defiant little bastards.”

Surrealist painter Salvador Dalí was terrified of grasshoppers. “I am 37 years old,” he wrote in 1941, “and the fright which grasshoppers cause me has not diminished since adolescence ... If possible, I would say it has become greater.” He went on to say that if a grasshopper ever landed on him while he was standing “on the edge of a precipice,” he’d instinctively jump to his death.

4. Ornithophobia

Traumatic childhood experiences involving birds—like, say, getting chased by a goose—can give birth to a lifelong fear of feathered critters. For Lucille Ball, they always reminded her of her father's untimely death when she was just a toddler: As her mother was delivering the horrible news, a couple of sparrows gathered by the kitchen windowsill.

“I’ve been superstitious about birds ever since,” Ball wrote in her autobiography. “I don’t have a thing about live birds, but pictures of birds get me. I won’t buy anything with a print of a bird, and I won’t stay in a hotel room with bird pictures or any bird wallpaper.”

5. Ailurophobia

Tabby cat against a gray background
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Lucy van Pelt (sort of) mentions ailurophobia in A Charlie Brown Christmas, although she bungles the nomenclature and tells Charlie Brown, "If you’re afraid of cats, you have ailurophasia." (The -phasia suffix generally refers to speech disorders, such as aphasia.) That being said, the fear of cats is a phenomenon that goes by many names, including gatophobia and felinophobia.

Rumor has it that Napoleon Bonaparte and lots of other famous conquerors were terrified of kitties. In Bonaparte’s case, the allegations are probably false; according to historian Katharine MacDonogh, “No record exists of Napoleon either liking or hating cats.” She thinks this myth reflects the long-standing cultural belief that our feline friends wield supernatural insights. “Cats have been endowed with a magical ability to detect the overweening ambitions of dictators, many of whom have consequently been accused of ailurophobia on the flimsiest evidence,” MacDonogh wrote in her book Reigning Cats And Dogs: A History of Pets At Court Since The Renaissance.

6. Alektorophobia

Chickens, hens, and roosters put alektorophobes on edge. A rare type of ornithophobia, this fowl-based fear is no laughing matter. One 2018 case study reported on a 32-year-old man who would experience heart palpitations, a sudden dryness of the mouth, and uncomfortable feelings in his chest upon seeing a neighbor’s hen. It was ultimately determined that the man's phobia was the result of a frightening childhood encounter he’d had with a rooster.

7. Ostraconophobia

“I have a lobster phobia, I don’t know why. I just don’t like them,” NASCAR driver Denny Hamlin told the press in 2017. “I cannot eat dinner if someone beside me is eating lobster.” The admission came just after Hamlin had won the Monster Energy NASCAR Cup Series. Why did that matter? Because the event took place at the New Hampshire Motor Speedway, where race-winners are customarily rewarded with giant, live lobsters. But when somebody approached Hamlin with a 44-pounder, he tried to flee the stage. Ostraconophobia, or fear of shellfish, can also manifest itself as a fear of crabs or oysters. The majority of people who deal with this phobia develop it after getting sick from the shellfish that makes them feel uneasy.

8. Ichthyophobia

Piranha fish on black background
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Ichthyophobia is a bit of an umbrella term that covers an irrational disdain of fish in a variety of situations. It can refer to the fear of being around live fish, the fear of eating dead ones, or the fear of touching them. A common version of that first anxiety is galeophobia, the widespread fear of sharks. And then there are those who are disturbed (and sometimes even physically sickened) by the sight or smell of fishy entrees; these ichthyophobes may take pains to avoid supermarkets with large seafood aisles.

9. Musophobia

Among the British adults who participated in a 2017 phobia survey, more than 25 percent reported that they were afraid of mice. By comparison, only 24 percent said they dreaded sharp needles or airplanes. In addition to disliking mice, musophobes are often afraid of other rodents, such as hamsters and rats.

10. Equinophobia

Sigmund Freud once wrote a case study on a boy who was terrified of horses. At age 4, Herbert Graf—referred to as “Little Hans” in the paper—had seen an overloaded work horse crumble to the ground in a heap. Following the traumatic incident, Hans became easily spooked while in the presence of horses; just the sound of clopping hooves was enough to trigger his anxiety. As a result, Hans often refused to leave the house.

Little Hans eventually overcame his fears, but equinophobia is still with us today. Kansas City Chiefs safety Eric Berry developed it after being bitten by a pony at a petting zoo when he was a child. Unfortunately for Berry, one of the Chiefs’s mascots is a live pinto horse named Warpaint. As former teammate Derrick Johnson told NFL Films, “He’s always watching for the horse, making sure the horse doesn’t look at him or do something crazy.” Berry has taken steps to overcome his horse phobia, though; in fact, he has even worked up the courage to (briefly) pet Warpaint.

11. Cynophobia

Pug wrapped in a pink blanket
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If you’re afraid of snakes, at least you’ll (probably) never have to worry about some coworker bringing his pet anaconda into the office. Cynophobes aren’t so lucky. Defined as the “fear of dogs,” cynophobia is an especially challenging animal phobia to have because, well, puppers are everywhere. Cynophobic people may go out of their way to avoid parks and tend to feel uncomfortable in neighborhoods where loud pooches reside.

As with ornithophobia, the fear of canines often stems from a traumatic childhood event. Therapists have found that, for many patients, the best way to overcome this aversion is through controlled exposure; spending quality time with a well-trained dog under a supervisor’s watchful eye can work wonders.

Survey: People Show More Affection to Their Dogs Than Their Humans

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iStock.com/damircudic

Valentine's Day is marketed as a celebration of love between two people, but for some human beings, the relationship they share with their dog takes precedent. Nearly half of pet owners have plans to celebrate the holiday with their pet, whether they're buying them a gift or making them a treat from scratch. That's one of the findings from a new report from Rover that shows just how much humans love their dogs—and how much dogs feel love from their humans.

After surveying 1450 U.S. adults who are dating or in a relationship, Rover found that many of them prioritize spending time with their canine companions. Sixty-seven percent reported gazing lovingly into their pet's eyes, and about 33 percent do this more often with their cute dog than with their human significant other.

The way our pets respond to this behavior suggests that dogs feel love, too. Phil Tedeschi, a University of Denver researcher and member of Rover’s Dog People Panel, says that dogs will wait for the opportunity to make eye contact with their humans. Previous research has shown that some dogs also express empathy when they think their owners are in distress.

When dog people aren't gazing at their pooches, they're finding other ways to show their affection. Nearly a quarter of dog owners take more pictures with their dog than with the humans in their life; a quarter spend more money on their dog than on their partner; and nearly half cuddle with their dog more often than they do with the person they're dating.

Pet parents also aren't afraid to cut people out of their life if they threaten their relationship with their dog. Forty-one percent say it's important that their dog gets along with their potential partners, and 53 percent would consider breaking up with someone who didn't like dogs or who was severely allergic to them.

You can check out the results of the report in the infographic below. And if you're looking for a last minute gift for Fido this Valentine's Day, here are some suggestions.

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