8 Shark Facts to Know Ahead of Shark Week

Scientists Are Still Discovering New Sharks

This is the recently discovered American Pocket Shark. It is about 5 1/2 inches long and is also bioluminescent. via /r/Awwducational https://t.co/NRO3yjBHf0 pic.twitter.com/sbcp5ltiaX

— Adorable (@Awwducational) July 22, 2019

Just when you think scientists must already know about every animal species in the world, they announce the discovery of new sharks. This month, Tulane University released a study confirming scientists discovered the American Pocket Shark, a tiny species that glows in the dark and lives in the Gulf of Mexico.

Scientists said they have only caught two examples of Pocket Sharks. The first was caught in 1970, off the coast of Chile, and measured 16 inches long. It was called the Mollisquama Parini.

The second pocket shark was the first American Pocked Shark, discovered off the Gulf coast in 2013. It measured just 5.5 inches long.

There Were at Least 34 Cases of Human-Provoked Attacks by Sharks in 2018

The International Shark Attack File looked at 130 cases of alleged shark attacks involving humans in 2018. Sixty-six of them were confirmed unprovoked attacks, but 34 others were confirmed provoked attacks.

"'Provoked attacks' occur when a human initiates interaction with a shark in some way," the group said. "These include instances when divers are bitten after harassing or trying to touch sharks, attacks on spearfishers, attacks on people attempting to feed sharks, bites occurring while unhooking or removing a shark from a fishing net, etc."

Florida had the most unprovoked shark attacks among U.S. states, with 16, making up 24 percent of the global total. In total, the U.S. had 32 unprovoked attacks, including one fatal incident, in 2018. This was a drop from 53 incidents in 2017.

Humans Are More Dangerous to Sharks Than Sharks Are to Humans

While humans might be afraid of sharks, they have every reason to be afraid of us. After all, we are the ones invading their territory, not the other way around.

"Sharks are not 'lurking' or 'infesting' our waters, they inhabit them," Melissa Michaelson of Brick, a volunteer with the Princeton-based Shark Research Institute, told APP.com. "It's their environment."
Michaelson also pointed out that sharks are good for the environment.

"Sharks play a large role in keeping our oceans and fish and marine mammal populations healthy and clean of diseased, dying and dead animals," Michaelson explained. "Sharks are our canaries in the coal mine. Not seeing them would be a true cause for concern."

Sharks are Constantly Developing New Teeth to Replace Old Ones

Sharks can have hundreds of teeth, but only some of them are at the front, ready to be used to chomp into food. According to Wonderopolis, great whites have about 50 teeth at one time, but those teeth are not permanent. Some sharks have more than 300 teeth in different stages of development and some sharks can over more than 50,000 teeth during their lives. Sharks usually have multiple rows of teeth, and those teeth do not have roots, unlike human teeth. They easily fall out, and it takes a couple of weeks for teeth from the back rows to move forward.

16 Percent of All Sharks are Threatened with Extinction

While there are over 500 known species of shark in the world, many are threatened with extinction. According to Nature.org, 16 percent of all sharks are ranked Vulnerable or higher by the International Union for Conservation of Nature.

One of the most endangered sharks is the Pondicherry Shark, which has not been seen in 50 years and is possibly extinct already. The shark was known to be living in the Indo-Pacific waters. Fishing is one of the top reasons for sharks going extinct.

"Increased public attention coupled with vocal public support is essential for advancing conservation policies," researcher David Shiffman wrote for Southern Fried Science. "The shark species at the highest risk of extinction aren't getting the attention they need, even from eco-friendly media that claims to be highlighting the shark species at the highest risk of extinction."

Some Sharks Eat Plankton Over Meat

While some of the most famous sharks are carnivores, not all are. As Sharks World notes, some eat plankton instead of meat. The whale shark, basking shark and megamouth shark all prefer plankton over meat. Carnivorous sharks usually eat marine mammals like dolphins, seals and sea lions, as well as large fish species. Some even eat seabirds.

A shark's digestive track is very different from a mammal's. They only eat 0.5 to 3 percent of their weight each day and it takes a long time for them to digest their food. The amount of food a shark eats depends on the species.

The Greenland Shark Can Live up to 272 Years, Possibly up to 500 Years

Back in 2016, a study found that the Greenland shark may be the longest-living vertebrate on earth. The study's authors said the shark, which lives in the deep waters of the North Atlantic, can reach at least 272 years old, or possibly up to 500 years.

"We had an expectation that they would be very long-lived animals, but I was surprised that they turned out to be as old as they did," study leader Julius Nielsen, biologist at the University of Copenhagen, told National Geographic. "The secret behind the success of this study is that we had young and old animals, medium-sized and large animals, and we could compare them all."

Sharks Swam in the Seas Before Dinosaurs Walked the Earth

Scientists believe that prehistoric sharks were swimming in the oceans before dinosaurs were walking on land. Some ancient shark species date back at least 420 million years, notes Sharks-World.

Scientists have learned about prehistoric sharks through their teeth, since their skeletons are made of cartilage instead of bones. Some teeth dating back to the Miocene epoch, or about 23 to 5.3 million years ago.