11 Facts About Tiger Sharks

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iStock

Weighing 1300 pounds or more and growing up to 15 feet, the tiger shark is the fourth-largest shark on earth. (Only whale sharks, basking sharks, and great whites get bigger.) On top of being big, tiger sharks are also pretty bizarre: They literally eat garbage, give birth to massive litters—and one of them was a player in Australia’s greatest unsolved murder mystery.

1. THEY’RE LIKE SWIMMING GARBAGE DISPOSALS.

Tiger sharks have broad diets: They eat everything from albatrosses, venomous sea snakes, and other sharks to manmade objects like paint cans, leather jackets, rubber tires, and even license plates. (That scene in Jaws where Hooper pulls a Louisiana plate from the stomach of a dead tiger shark is scientifically accurate!)

2. DON’T CONFUSE THEM WITH SAND TIGER SHARKS.

You might assume that the tiger shark (Galeocerdo cuvier) and the sand tiger shark (Carcharias taurus) are cousins, but the latter is more closely related to the great white (Carcharodon carcharias) than it is to the tiger shark.

3. NOT ALL OF THEM HAVE STRIPES.

Hear the word tiger and you think vertical stripes, but those stripes evolve over time. Baby tiger sharks—a.k.a. pups—are covered in roundish gray spots that fuse into stripes as the sharks mature. After a certain age, the stripes start to fade; they’re barely visible in full-grown adults.

4. TIGER SHARKS PREFER WARM WATER.

Tiger sharks are seen in tropical to warm temperate waters all over the world, and a study published in Global Change Biology in March 2018 revealed that the sharks have a "Goldilocks" zone. “Our study suggests that 22 degrees [Celsius, 71.6 degrees Fahrenheit] is not too cold for the animals and it’s not too hot for them,” lead author Nicholas Payne told the BBC. “It’s about right in terms of their optimal preference for temperature.” The scientists reached that conclusion after monitoring tagged sharks near Hawaii and comparing those findings to several decades’ worth of Australian fishing records.

5. THEY HAVE NOTCHED TEETH.

the teeth of the tiger shark with serrated edges

If you could pry open a tiger shark’s jaws, you’d see teeth with dramatic notch tips that point sideways. You'd also notice that the teeth on the left and right halves look like mirror images of each other. A tiger shark’s teeth have a dual function: They help the fish grasp onto struggling victims and can shear right through the thickest of hides, making them well-equipped to go after just about any prey that’s available.

6. THEY MIGHT BE THE ONLY SHARKS TO REGULARLY HUNT SEA TURTLES.

Every year, 12,000 nesting sea turtles visit Raine Island in the Great Barrier Reef, and tiger sharks—which hunt the turtles—aren't far behind.

To get its meal, the shark first has to get a good grip, but the turtle doesn't make it easy: When a shark gets too close for comfort, a turtle may respond by turning itself sideways so the top of the carapace is perpendicular to the shark’s jaws, making themselves too wide to bite into. Turtles in this position will also swim in tight circles around the predator, which protects the reptile’s vulnerable flanks.

According to a 2016 study, the sharks tend to avoid healthy turtles and instead conserve energy by going after sick or dying (or dead) turtles.

7. SEA GRASS SEEMS TO BENEFIT WHEN TIGER SHARKS ARE AROUND.

Though Australia's Shark Bay is home to a diverse array of organisms, it got its moniker for the 28 shark species that have been seen there—including tigers, which are especially common.

Sea grasses are the backbone of Shark Bay's ecosystem; they provide shelter for small animals and food for big herbivores. But the grasses were decimated after a 2011 heat wave. Since then, they've been making a gradual comeback, and scientists have noticed that they grow at a higher rate in places frequented by tiger sharks. This is probably because the sharks frighten off sea turtles and dugongs who like to eat the grass. “Just the fear of sharks can be enough, in many cases, to keep a marine ecosystem healthy and able to respond to stresses,” biologist Michael Heithaus said in a news release.

8. TIGER SHARKS GIVE BIRTH TO HUGE LITTERS.

Female tiger sharks are pregnant for 14 to 16 months and give birth to at least 10 pups, with around 30 being the average. But sometimes, they have many, many more than that: There have been reports of females birthing 80 pups at once. Usually, newborns weigh between six and 13 pounds.

9. IN THE ATLANTIC, THEY MIGRATE SOUTH FOR THE WINTER.

There's still a lot to learn about the travel habits of tiger sharks. A seven-year study found that Hawaiian females tend to travel more often—and more widely—around the island chain than males do. Another analysis, published in 2015 in Scientific Reports, focused on 24 adult tiger sharks in the Atlantic and found that, in the winter months, they stayed in the area around the Caribbean and West Indies. Then, for summer, they headed north and spent the warmest part of the year in the mid-Atlantic, venturing as far north as Connecticut (and far away from the coast). No one knows why the sharks make the trip, but it may have something to do with the young loggerhead turtles who dwell in those northern waters.

10. ONE TIGER SHARK BARFED UP A MURDER MYSTERY.

In April 1935, Coogee Aquarium in Sydney, Australia was looking for a big fish to occupy its newly-built pool. On a fishing trip off Coogee beach, Bert Hobson snared a 13-foot tiger shark for the aquarium.

The shark was a big hit at the aquarium, but it didn’t last very long. Seven days after its arrival, it got sick and vomited up a bird, a rat, some nasty-looking brown goo—and a human arm, which had a rope tied around its wrist and a forearm tattoo of two boxers.

An amateur boxer named James Smith had recently gone missing, and he had the exact same tattoo on one arm. Forensic analysis determined that the arm hadn’t been bitten off—it had been removed from the rest of Smith's body with a knife.

Detectives learned that Smith was last seen playing cards at the Hotel Cecil in Cronulla with his longtime associate Patrick Brady, a forger, who quickly became the number one suspect. The authorities were later informed by a boat-builder (and suspected criminal) named Reginald Holmes that Brady had murdered Smith in an argument. But before Holmes could testify in court, somebody shot him.

Brady's lawyers argued that a severed arm didn’t constitute proof of a murder. Smith, they argued, might still be alive somewhere—sans one limb, of course. Brady got off scot-free, which was more than could be said for the poor tiger shark—it died in captivity. A necropsy did not reveal any other human remains.

11. IT’S RARE, BUT TIGER SHARKS HAVE BEEN KNOWN TO SHARE FOOD WITH CROCODILES AND GREAT WHITES.

Bloated, rotting whale carcasses lure all kinds of animals out of the woodwork. Carnivores that normally don’t cross paths sometimes end up feasting on the dead mammals side-by-side. In 2015, two great whites and three tiger sharks were filmed tearing into the colossal body of a sperm whale near New South Wales, Australia. Years earlier, off the South African coastline, witnesses saw members of both species eating a Byrd’s whale carcass [PDF]. Australian drone footage from 2017 (above) shows a humpback carcass getting picked apart by both tiger sharks and saltwater crocodiles. Look at the video closely and you’ll see the croc and fish coming within a few yards of each other.

This Wall Chart Shows Almost 130 Species of Shark—All Drawn to Scale

Pop Chart Lab
Pop Chart Lab

Shark Week may be over, but who says you can’t celebrate sharp-toothed predators year-round? Pop Chart Lab has released a new wall print featuring nearly 130 species of selachimorpha, a taxonomic superorder of fish that includes all sharks.

The shark chart
Pop Chart Lab

Called “The Spectacular Survey of Sharks,” the chart lists each shark by its family classification, order, and superorder. An evolutionary timeline is also included in the top corner to provide some context for how many millions of years old some of these creatures are. The sharks are drawn to scale, from the large but friendly whale shark down to the little ninja lanternsharka species that lives in the deep ocean, glows in the dark, and wasn’t discovered until 2015.

You’ll find the popular great white, of course, as well as rare and elusive species like the megamouth, which has been spotted fewer than 100 times. This is just a sampling, though. According to World Atlas, there are more than 440 known species of shark—plus some that probably haven't been discovered yet.

The wall chart, priced at $29 for an 18” x 24” print, can be pre-ordered on Pop Chart Lab’s website. Shipping begins on August 27.

Can You Really Suck the Poison Out of a Snakebite?

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iStock

Should you find yourself in a snake-infested area and unlucky enough to get bitten, what’s the best course of action? You might have been taught the old cowboy trick of applying a tourniquet and using a blade to cut the bite wound in order to suck out the poison. It certainly looks dramatic, but does it really work? According to the World Health Organization, approximately 5.4 million people are bitten by snakes each year worldwide, about 81,000 to 138,000 of which are fatal. That’s a lot of deaths that could have been prevented if the remedy were really that simple.

Unfortunately the "cut and suck" method was discredited a few decades ago, when research proved it to be counterproductive. Venom spreads through the victim’s system so quickly, there’s no hope of sucking out a sufficient volume to make any difference. Cutting and sucking the wound only serves to increase the risk of infection and can cause further tissue damage. A tourniquet is also dangerous, as it cuts off the blood flow and leaves the venom concentrated in one area of the body. In worst-case scenarios, it could cost someone a limb.

Nowadays, it's recommended not to touch the wound and seek immediate medical assistance, while trying to remain calm (easier said than done). The Mayo Clinic suggests that the victim remove any tight clothing in the event they start to swell, and to avoid any caffeine or alcohol, which can increase your heart rate, and don't take any drugs or pain relievers. It's also smart to remember what the snake looks like so you can describe it once you receive the proper medical attention.

Venomous species tend to have cat-like elliptical pupils, while non-venomous snakes have round pupils. Another clue is the shape of the bite wound. Venomous snakes generally leave two deep puncture wounds, whereas non-venomous varieties tend to leave a horseshoe-shaped ring of shallow puncture marks. To be on the safe side, do a little research before you go out into the wilderness to see if there are any snake species you should be particularly cautious of in the area.

It’s also worth noting that up to 25 percent of bites from venomous snakes are actually "dry" bites, meaning they contain no venom at all. This is because snakes can control how much venom they release with each bite, so if you look too big to eat, they may well decide not to waste their precious load on you and save it for their next meal instead.

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