Bamboo sharks walk. Yellow Ninja sharks glow in the dark. Whale sharks can carry up to 300 babies at once – at different stages of the fetus and from different fathers. Zebra sharks are experiencing a “virgin birth”.
This is just a sample of the most interesting shark discoveries of the last ten years. About 500 known species of these toothy fish pass through the waters of our planet, from the size of a bite to the size of a bus. Scientists are still well acquainted with most of them. Since 2000, when researchers found shark populations around the world, shark research has grown in many fields of study, from paleontology to neuroscience to biomechanics.
A quarter of a century later, one thing is clear: Sharks are not senseless killers that often portray themselves in popular culture. In the beginning, these fish have large brains, the relative size of which varies from species to species.
Want more sharks? Tune in to five full weeks of SharkFest for action-packed, heartbreaking and informative performances about these amazing creatures. SharkFest is broadcasting on Sunday, August 9, on Nat Geo WILD.
“Your brain is like a shark,”; says Kara Yopak, a comparative neuroanatomist at the University of North Carolina at Wilmington. In fact, as one of the most primitive creatures on Earth, sharks first evolved as it is called the “vertebrate brain state,” which contains familiar structures such as olfactory bulbs, the cerebellum and parts of the forebrain, and the midbrain.
“The biggest misconception is that sharks are these pre-programmed food machines with small brains,” says Yopak. “I learned that’s not the case.”
As shark science expands, so does the urgency of protecting many species, two-thirds of which are threatened by overfishing, climate change, habitat loss and poaching. One study suggests that if the world increased its marine protected areas by only 3 percent, it could potentially save the 99 most endangered sharks, many of which are the best predators to help balance their ecosystems. (Read about the six sharks you’ve never heard of.)
Here are more findings that have overturned our knowledge of sharks on their heads.
Sharks travel further than they ever imagined.
Scientists such as Barbara Block, a marine biologist at Stanford University, place GPS marks on sharks and track their movements – revealing their secret lives.
Scientists previously thought that great white sharks near California would be stranded near the coast, hunting lions and seals. But with advancing tracking technology that allowed scientists to tag sharks for extended periods of time, Block and colleagues learned that predators traveled thousands of miles to the warm water of the open Pacific Ocean each winter, making unexplained night dives.
Satellites designed this Colorado-sized Pacific region, as the dubbed cafe with white sharks had no food. But they were wrong. Scientists have found an area rich in shrimp, worms, tuna, octopus and various deep-sea creatures. Now that we know that this white shark hunt is so important to their life cycle, conservationists are trying to establish it as a UNESCO World Heritage Site.
On the east coast of the United States, a big white named Mary Lee has become a smaller celebrity in recent years, jumping to the beach between Bermuda, Florida and the Jersey Shore, and surprising scientists with her frequent ghosts. Mary Lee has not appeared since 2017, but has active accounts on Facebook and Twitter.
Other species of sharks are less peripathic, performing epic migrations. In 2014, the great white Lydia became the first known of its kind to cross the Atlantic Ocean. And in 2017, a whale shark named Anne broke records by traveling about 12,400 miles across the Pacific Ocean for just over two years.
Dental scales help them swim.
All sharks are covered with hundreds of thousands of tiny cartilages that mysteriously regenerate when lost.
“Each one is like one of your own pulp, dentin, and enamel teeth,” said George Lauder, a biologist and fish robot at Harvard University. “The teeth in our mouths come from an old scale that covered animals like sharks about 400 million years ago.”
Recent advances in imaging technology, 3D printing and robotics have revealed how dentins help sharks swim. In laboratory experiments, Lauder found that shark-like material moved faster and consumed less energy than smooth material.
The secret? Denticles reduce resistance and increase lift and tension. Size also matters; smaller toothbrushes increase speed and larger toothbrushes decrease it. The patterns of teeth and their sizes may vary from shark to individual.
Filter feeders are more complex than expected.
Scientists once thought that all fish fed a filter used mouths as colanders: anything too big to fit through jammed holes; The rest came out with water. But Erin “Misty” Paig-Tran, a functional anatomist at California State University in Fullerton, wondered how that could be true. Manta rays and whale sharks, which she fed on a filter, studied near Cancun, Mexico, fed in the same place at the same time, but ate completely different things.
By testing three-dimensional models of sharks and manta filters in the laboratory, she revealed how they do it. By adjusting the swimming speed and the width of the mouth or gill slots, fish can catch their preferred food by manipulating the water flowing through the bullets. In general, the higher the speed of the water, the smaller the particles of food they consume. (Find out how the biggest sharks in the world disappear.)
Filter-fed species have different strategies. Whale sharks stop and suck food, surface and sips, or swim with their mouths open. Megamouths take huge sips with their caries-covered filters. Shark sharks swim with their mouths open.
At least one species of shark is omnivorous – and probably more.
In 2007, scientists studying the hood shark diet found a belly full of up to 60 percent of seaweed.
“Everyone thought the sharks were carnivores,” said Samantha Leigh, a postdoctoral student studying sharks in the Paig-Tran lab. Sure, they could eat seagrass by accident, but could their bodies do anything with all that green?
About ten years later, Leigh, then a graduate student at the University of California, Irvine, fed a captive sea shark that was labeled with isotopic markers – special molecules that allowed her to see where seaweed nutrients moved through the body. She found fish digested in about half of the organic matter in seaweed and incorporated nutrients into her bodies.
“It’s very similar to what some young sea turtles spend,” he says. It is the first omnipotent diet that sharks have ever experienced. How they do it remains mysterious, but Leigh claims that sharks can get help from germs in their entrails – just like humans.
Sharks inspire materials and products that benefit humans.
In 2012, Lauder tested swimsuit material to reduce drag, such as the sharkskin worn by 80 percent of the winning swimmers at the Sydney Olympics. Speedo LZR suits, which are now banned due to fears of unfair advantages, have increased swimmers’ performance by about 7 percent. Swimwear companies like Speedo are trying to design new suits to replace LZRs, which are not considered “technological doping”.
Lauder’s research found that suits did not actually reduce traction for swimmers. “The surface of these suits is really nothing like a real shark,” Lauder notes. The real key was that tight overalls all over the body smooth out bumps on human skin.
Paig-Tran of California State University says filter-shark sharks are the inspiring design for high-volume, energy-efficient self-cleaning industrial filters for purposes such as wastewater treatment or even the removal of microplastics from water bodies.
“A lot has happened in the last 10 years,” says Paig-Tran. “The more we learn about sharks, the more fascinating they become.”