Hi, I'm Erin McCarthy, editor-in-chief of Mental Floss.com.

Welcome to Mental Floss video and did you know that there are more than 500 types of sharks? They range in size from 8 inches to 40 feet long.

My personal favorite is the cookie cutter shark, which grows to up to 22 inches. It uses its suction cup-like lips to attach itself to prey and once it's firmly stuck on there the shark spins its body using its bottom row of serrated teeth to take out a cone-shaped chunk of flesh. Typically cookie cutters feed off of sea creatures that are much bigger than them but they've also taken bites out of a couple of humans and they've been known to leave their mark on submarines, too.

And that's just the first of many awesome facts about sharks that I'm going to share with you today. Peter Benchley's 1974 novel Jaws was inspired by a fisherman who caught a 4,500 pound behemoth in Montauk in 1964. The novel wasn't always going to be called Jaws.

Alternate titles included The Stillness in the Water, The Silence of the Deep, Leviathan Rising, and The Jaws of Death. Later, Benchley became a conservationist who used his pen to tackle misconceptions about the fish. In 2006 he said, quote, "I could never write that book today.

Sharks don't target human beings and they certainly don't hold grudges." Fun fact: Benchley makes a cameo in Steven Spielberg's 1975 adaptation of his novel. He plays a TV news reporter. Shark attacks, by the way, are actually very rare.

In 2018 there were 66 confirmed unprovoked attacks in America. The risk of dying from a shark attack is one in three million seven hundred and forty eight thousand and sixty-seven. You're more likely to be killed by fireworks, a train crash, or MRSA- that antibiotic-resistant bacteria- than you are by sharks.

Worldwide, the risk is even lower. There is one particularly ferocious shark that has been known to attack humans, though. Weighing in at roughly 32 ounces and covered in brown, fur-like material, this species is totally new to science but we actually have one here today.

Ladies and gentlemen: the Simba shark. Vicious. Sharks have been around for a while.

Thanks to fossils we know that they've been swimming the seas for at least 400 million years, and some species can live to be incredibly old. Researchers in 2016 used radiocarbon dating on the eyes of 28 Greenland sharks and determined that one female might have been around 400 years old. Speaking of Greenland sharks, their meat is a delicacy in Iceland. it's called Hákarl.

The Sharks meat is toxic when fresh so it has to go through a fermentation process that involves burying the shark's body in sand under rocks for 6 to 12 weeks. The meat is then cut up and hung to dry. The finished product has a strong scent of ammonia.

Anthony Bourdain called it quote, "...the single worst most disgusting and terrible tasting thing..." he'd ever eaten. Great white sharks have a man-eating reputation but they're much more interested in seals and sea lions. They have a forty to fifty-five percent accuracy rate catching their seal prey, according to research.

The hunting process also often involves the sharks coming fully out of the water, which is called breaching. Great whites are fast, too. They can swim at 35 miles an hour for short bursts.

That's why many shark researchers think the old tale of "great whites attack humans because they think we're seals" is a myth. Great white shark attacks on humans are much less vicious than the way sharks attack prey like seals and sea lions. One study reported that in 76% of attacks on surfers the force would not have stunned a pinniped.

In most cases they're probably just curious, though still potentially deadly. One expert told discovery that if you do spot a shark the best course of action is to remain calm and try to slowly get back to safety. Despite what you might see in movies and TV, great white sharks aren't typically found in aquariums, though not for lack of trying.

Since the 1970s aquarium workers who have tried to keep the sharks in captivity have been having basically the same tragic experience: finding a great white shark sick, then dead, within a week. While in enclosures the sharks can't swim at the high speeds or over the distances that they're supposed to, so they bump into the glass and get hurt, or just stop swimming and die. Younger sharks have tended to do better.

The Monterey Bay Aquarium was able to keep a young great white for 198 days, but released her after she started going after other sharks. What are you gonna do? Sharks gonna shark.

Another shark you probably won't see in captivity these days is the tiger shark- not to be confused with the sand tiger shark, which is a completely different species found in aquariums around the world. Anyway, female tiger sharks have many, many pups. After 13 to 16 months of pregnancy a female might give birth to between 10 and 82 little shark babies.

The average is around 30. It's not unusual for a female shark to give birth to her pups in the place where she herself was born. One study, which began in 1995 and concluded in 2012, found this to be the case with lemon sharks in the Bahamas. *Sings* It's not unusual for a female shark to give birth to her pups in the place where she was born.*Laughing* Female mako sharks also have an interesting habit.

They stay away from male Makos. In research that lasted for four months a biologist and his team recorded 264 males and 132 females in the East Island area. They found that there was a clear divide between where males resided versus females and they were baffled as to why.

One of them suggested that it might have something to do with the fact that males often bite their intended mate, so maybe the females were trying to avoid that whole situation. Fun fact: biting is often a part of shark copulation because the males have to hang on to something. ... Why are so many of my fun facts about animal sex?

It's not just biologists who have taken an interest in sharks. In 2002, software programmer Jason Homberg went scuba diving on vacation and spotted the rare whale shark. He wanted to make the spotted sharks less mysterious so he teamed up with an astrophysicist and a marine biologist.

They were able to adapt an algorithm that had been created for the Hubble Space Telescope program and use it to start identifying sharks. The algorithm was initially for star mapping, so it made sense as an algorithm for shark spot mapping. They've since created a database with 32,000 pictures of whale sharks.

The database has helped them track the animals' locations, which means they can learn more about the whale shark lifestyle. Of course hammerhead sharks have an identifier as well, but why do their heads look like that? Well, it may help with hunting.

Sharks are able to sense electric fields in water, which allows them to determine if they're in the vicinity of prey. One theory is that hammerhead sharks have more of those sensory organs in their heads so they can find prey better. Their eyes being so far apart helps, too.

They have better binocular vision. In addition to using electric fields to sense prey, sharks also use them to sense predators. Even shark embryos have that ability.

In a study published in 2013 a group studying brown-banded bamboo shark embryos found that when the embryos were in the electric field of a predator their gills stopped moving. Sharks sometimes like to rest in groups. Nurse sharks and white tip reef sharks have been observed gathering in groups of 2 to 40, usually in a safe place like a crevice, often just napping.

A basking shark looks very weird when it decomposes. It quickly loses parts of its jaw and tail, so it's not unusual for people who spot them on the shore to believe they found a sea monster. This happened in 1970 in Massachusetts and some scientists believed it happened again in March 2018.

Responsibility for that unidentified sea creature, though, was eventually claimed by Zardulu the myth-maker, an artist who specializes in viral hoaxes. In the 1930s a tiger shark at Coogee aquarium in Australia vomited up a human arm, evidence that became part of a murder trial. Thanks to a tattoo on the arm the person it belonged to, James Smith, was identified.

It turned out that he was missing and the shark hadn't bitten the arm off- it was cut off with a knife. There was a suspect, Patrick Brady, and a man willing to testify that Brady was responsible. But that witness was shot before the trial.

Brady's lawyer claimed that for a homicide there needed to be a body and all they had was an arm. Brady went free. The shark, unfortunately, was not so lucky.

It died. The deep sea-dwelling goblin shark has a jaw that shoots outward to grab prey in what scientists have dubbed slingshot feeding, so it's no wonder they often get compared to monsters. In fact, Japanese fishermen named them Tengu Zame.

Tengu is a demon with a long nose that sometimes steals children and zame means shark. That's how we got our English translation, goblin shark. Fun fact: the goblin shark can deploy its jaw at 10.1 feet per second which is roughly twice the speed that New York City pedestrians walk.

By the way, not all sharks are ferocious carnivores. The bonnethead shark has long been observed to eat sea grass. Until recently it was unclear if they were digesting it but in 2018 it was confirmed through stable isotope analysis that they actually were, making them the first known omnivorous shark.

There are multiple types of lantern sharks, including a dwarf lantern shark that doesn't grow larger than eight inches. These sharks have bellies and fins that glow so it's thought that when there's a predator swimming beneath them the predator doesn't know the difference between the shark and the light coming into the ocean from the sun. We think of sharks as strictly ocean dwellers but that's not the case for all species.

Bull sharks are unusual in that they can tolerate fresh water. Most sharks have to be in salt water because that's what their bodies can handle. Put them in fresh water and they'll lose too much salt.

But bull sharks are better able to retain salt in their bodies so they can travel in fresh water. And, in fact, in 1937 one was caught all the way up in Alton, Illinois where you wouldn't typically expect to encounter a shark. Megalodons were huge, perhaps about 50 feet long, but there are now theories that the measly great white shark, at less than half that size, may have caused them to go extinct.

It was previously believed that they went extinct around 2.6 million years ago but when a group of paleontologists and geologists went back through the fossils and data they pegged it at 3.6 million years ago, which just so happened to be the time that great white sharks were emerging. They were probably able to go head-to-head with younger megalodons and out-compete them for food. Just to give you a better idea of how huge the megalodons were, their teeth could be around seven inches long.

And, in fact, you might want to be on the lookout for them. In 2018 a couple found a fossilized megalodon tooth on a beach in North. Carolina.

One famous megalodon tooth owner was Thomas Jefferson. He loved fossils and even kept them on display at the entrance of Monticello. Today, his megalodon tooth is at the Academy of Natural Sciences in.

Philadelphia and, of course, he signed it. Finally, a fact about every toddler's favorite song. Before Pinkfong's version of "Baby Shark" became one of the most viewed YouTube videos of all time, it was a common song for kids to sing at camps.

But when Jonny Only turned it into the bop that we all know today, he did change some things. In the original lyrics the sharks attack people and even kill them. Peter Benchley would not approve.

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