Sharks are among a group of animals with a 6th sense that humans don’t have – they use Earth’s magnetic field to navigate

bonnetheads sharks
Bryan Keller holding a bonnethead shark.

Shark species have an uncanny ability to find their way back to the same feeding grounds every year – even areas thousands of miles away.

According to a study published Thursday, that’s because sharks have a superior navigational tool at their disposal: They can orient themselves using Earth’s magnetic field.

They’re far from the only animals to do so. Birds, whales, and many other species use the same sixth sense to plot their migrations.

Bryan Keller, a biologist at Florida State University who co-authored the new study, likens this sense to “having an ‘internal GPS.'”

“This is, in my opinion, the best explanation for how migratory sharks successfully navigate during long-distance movements,” Keller told Insider.

‘Sharks garner map-like information from the magnetic field’

Earth's Magnetic Field
An illustration of Earth’s magnetic field.

Nearly 2,000 miles below Earth’s surface, swirling iron in the planet’s outer core conducts electricity that generates a magnetic field. This field stretches all the way from the planet’s interior to the space surrounding the Earth. It’s what protects the world from deadly solar radiation.

But the direction that the electromagnetic energy flows, as well as the strength of the resulting protective sheath, depends on where on the planet’s surface you are. So animals that use the magnetic field to orient themselves do so by detecting these differences in field strength and flow. They then use that information to figure out where they are and where to go.

Scientists long suspected sharks could navigate using the field, since the animals can sense electromagnetic fields in general. But that hypothesis had been difficult to confirm until Keller’s study.

His team examined the bonnethead shark, known as Sphyrna tiburo, because the species exhibits site fidelity – meaning it returns to the same estuary habitats each season.

“This means the sharks have the capability to remember a specific location and to navigate back to it,” he said.

bonnetheads sharks
An overhead shot of bonnethead sharks in a holding tank.

The team captured 20 bonnetheads off the coast of Florida in the Gulf of Mexico, then placed the sharks in a 10-by-10-foot tank. They generated a tiny magnetic field within a 3-square-foot area of that tank. (Bonnetheads only reach 4 feet in length, which made them an ideal species to study in such a small pool, Keller said.)

The team then tweaked that localized magnetic field to mimic the electromagnetic conditions of various locations hundreds of miles away from where they’d caught the sharks. If the animals were truly relying on magnetic-field cues to navigate, the thinking went, then the bonnetheads would try to reorient themselves and start swimming in the direction they thought would lead to the Florida coast. That’s exactly what happened.

When the researchers mimicked the conditions of the magnetic field on Florida’s Gulf Coast, the animals exhibited no preference in which direction they were swimming – suggesting they assumed they were already in the right place.

“I’m not surprised that sharks garner map-like information from the magnetic field, because it makes perfect sense,” Keller said.

Many animals use the magnetic field for navigation

Even though the new study was done on bonnetheads, Keller said the findings likely apply to other shark species as well.

Great White Shark
A great white shark heads near the Neptune Islands, Australia, in June 2014.

How else could a great white, for example, migrate from South Africa to Australia – a distance of more than 12,400 miles – then return to the exact same chunk of ocean nine months later?

“En route to Australia, the animal exhibited an incredibly straight swimming trajectory,” Keller said of great whites. “Given that the magnetic field is perhaps the only constant and ubiquitous cue available to these migratory sharks, it is sensible that magnetic-based navigation is responsible for facilitating these incredible navigational successes.”

Other navigational cues do exist, including currents and tides, but Keller said the magnetic field “is likely more useful than these other aids because it remains relatively constant.”

Biologists still aren’t sure how sharks detect the field, but a 2017 study suggested that the animals’ magnetic receptors are probably located in their noses.

The ability to detect and orient using the magnetic field is fairly common in the animal kingdom overall, according to Keller. Scientists have observed that type of behavior in bacteria, algae, mud snails, lobsters, eels, stingrays, honey bees, mole rats, newts, birds, fish like tuna and salmon, dolphins, and whales.

Sea turtles, too, rely on magnetic cues when they migrate thousands of miles to lay eggs on the same beaches where they hatched.

Two_Wire_Fox_Terriers
Two wire-haired Fox Terriers.

Dogs, meanwhile, can find their way home both using their impressive sense of smell and by orienting themselves using the magnetic field, according to a June study.

“The magnetic field may provide dogs with a ‘universal’ reference frame, which is essential for long-distance navigation,” that study said.

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Here’s what would happen if all insects on Earth disappeared

  • Although it’s impossible to say exactly what would happen if all insects on Earth suddenly vanished, it’s likely that civilization and ecosystems would be in serious trouble.
  • Nitrogen-rich feces would potentially build up, choking plant life and preventing new growth.
  • Meanwhile, no dermestid beetles and other corpse-eaters would lead to fewer custodians available to clean dead bodies and recycle their nutrients back into the ecosystem.
  • See more stories on Insider’s business page.

Following is a transcript of the video.

Narrator: Humans might have built civilizations, but insects own the world. After all, over half of all known species are insects. So if they all suddenly vanished, you’d notice. No more summers of singing cicadas and flickering fireflies. No bees to pollinate apple, cherry, peach, or almond trees. No one to make honey. A world without insects means a world with empty grocery-store shelves. But that would be just the beginning of our problems. Now, it’s impossible to say exactly what would go down, but here’s a worst-case scenario of what could happen if all the insects disappeared.

There are a few insects most people would be happy to see vanish. Like mosquitoes. They kill hundreds of thousands of people every year by transmitting malaria, West Nile virus, and other diseases. But if they disappeared tomorrow, we might actually miss them. There are over 3,000 species of mosquitoes on Earth, all of which are food to birds, bats, frogs, and other animals. No more mosquitoes means these creatures and the animals that eat them could go hungry. The same goes for the dreaded cockroach, a protein-packed meal for birds, rodents, and even humans in some parts of the world. If we lost all 4,400 species of roach, entire ecosystems would struggle to survive. Believe it or not, we’d have even worse troubles ahead since we’d face a serious poop problem without one of the world’s greatest recyclers, the dung beetle.

You see, history has taught us exactly what happens when these critters can’t do their job. Back in 1788, the British introduced cattle to Australia, and these cows pooped a lot. Each one poops enough to fill five tennis courts every year. But while the dung beetles back in Britain would eat and break down cow poo, the native Australian beetles wouldn’t touch the stuff because they evolved to munch only on dry, fibrous marsupial dung. So the cow poop piled up. By 1960, the cattle had carpeted 500,000 acres of pasture in dung. That’s enough to cover over half of Rhode Island, and while a little bit of poop is great for fertilizer, this ocean of dung would flood plants with nitrogen, making it impossible for anything to grow. So, imagine if all 8,000 species of dung beetle, plus other doo-dining insects, like flies, vanished worldwide. The land would be knee-deep in…you know.

Farmland, forest, and desert would all collapse, and floating throughout would be loads of corpses. You see, most animals won’t eat dead bodies. That’s where flesh-eating beetles, aka dermestids, and other corpse-munching insects come in. Over 500 species of these grisly undertakers live worldwide, devouring dead flesh until nothing but bone remains. Without them, there would be fewer custodians around to clean up the mess. Sure, there would still be hungry vultures and bacteria around to help, but it wouldn’t be enough.

So, that’s where we could end up in an insect-less world. Starving to death while drowning in a sea of poop and corpses.

EDITOR’S NOTE: This video was originally published in August 2019.

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Why we don’t have birth control for men

  • The condom was invented more than 5,000 years ago. While it’s made some strides since then, men are still left with few options for birth control, besides a vasectomy.
  • It’s not due to a lack of interest, but a lack of funding for research – and biology.
  • Men produce millions of sperm each day. Even if that count is reduced by 90%, they could still be fertile.
  • There are new methods coming, but experts say it will be years, if not decades, before they hit the market.
  • Visit BusinessInsider.com for more stories.

Following is a transcript of the video.

Narrator: Did you know the condom is over 5,000 years old? That’s right, some of the first forms of birth control date back to around 3,000 BC, and while the condom has made some strides since the Bronze Age, men still don’t have a much better option all these millennia later. Besides a vasectomy. Especially compared to the pills, IUDs, and implants available to women today. So why don’t we have birth control for men? In 2002, researchers asked more than 9,000 men across four continents whether they’d be willing to use contraception capable of preventing sperm production. Over half said yes. So the problem isn’t lack of interest, it’s partly human biology. Women ovulate just one or two eggs each month. Men, on the other hand, produce sperm daily, and it’s not just one or two.

There’s literally hundreds of millions of sperm produced each day, so because there’s so many sperm produced, actually, you can reduce your sperm number over 90% and still be completely fertile. Narrator: To reach infertility, a man’s sperm count needs to be somewhere around 1 to 10 million per milliliter, but getting there is near impossible, at least without side effects. That’s because sperm count is tied to the production of testosterone. In the past, researchers tried decreasing testosterone in an effort to decrease sperm count.

The problem is you don’t have any libido, you have very little testosterone to act on other tissues and so forth, and so the side effects were so dramatic that it really wasn’t ever going to be a contraceptive pill. Narrator: Scientists also tried using different compounds that attack the cells that produce sperm. But again, biology got in the way. Germ cells, as they’re called, developed inside a fortress-like structure within the testes.

So literally, nothing can get through it. There’s been a lot of small molecule studies to try and actually attack the germ cell to stop it from working. Literally, I can think of 10 or 15 different compounds that actually have been developed to do that, but they don’t work because of that barrier. Narrator: But the complex male anatomy isn’t the only problem. It’s also funding or lack thereof. In 2002, two big pharmaceutical companies took interest in male contraception, Schering and Organon. And together they funded a large clinical trial on a hormone-based contraceptive, offering hope that a pill backed by Big Pharma might be on the horizon.

Then these two companies became, as you know, acquired by bigger company, and then even bigger company, so now they are merged in huge companies, and women’s health is still a priority in many of the companies, but men’s health became part of the general matter of health. And therefore, the development of contraception becomes a really very low priority. Narrator: According to Dr. Wang, male contraception was also too risky for Big Pharma at the time. The long-term side effects were unknown. Companies were concerned that women might not trust it, and despite the survey results, it was unclear whether men would actually use a hormone-based contraception. Today, the limited funding comes mostly from government agencies like the National Institutes of Health. But there are in fact some promising lines of research. Dr. Wang is working on a gel that can lower testosterone where it matters, in the testes where sperm is produced, while keeping testosterone levels normal elsewhere. That means low sperm count and, more importantly, no major side effects.

We have preliminary studies to show that if we give the gel and if the man applies the gel, 90% of the men will reach the level that you talk about, 1 million per mil.

And Skinner is pursuing a new approach, shutting down Sertoli cells, which are a part of that impenetrable barrier that houses germ cells.

So if you shut down the Sertoli cell, then you shut down the sperm production. Narrator: But perhaps most promising is a sort of reversible vasectomy that’s in the works.

So they have this ability to inject this gel into what’s called the vas deferens, and it makes this plug, so then essentially it does the same thing, but you’re not cutting it. Then believe it or not, you can actually inject this chemical mixture, which will dissolve the plug, and so then you can get your fertility back. Narrator: But as promising as these approaches may be, they’re still years, if not decades, out, Skinner says. And without more funding, some of them may never hit the market. So at least for now, men are left with few options. Irreversible vasectomies, pulling out , and that slightly updated Bronze Age invention.

EDITOR’S NOTE: This video was originally published in April 2019.

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Why you should never release your pet goldfish into the wild

Goldfish may look small and cute in your home, but in the wild it’s a different story. Releasing them into your local stream or lake is a bad idea. Following is a transcript of the video.

Right now, Washington state is fighting off an invasion! The culprit? Goldfish. Yup, you heard right.

Thousands of goldfish have infested the West Medical Lake and are crowding out the native fish population. How did this happen? The Department of Fish and Wildlife thinks that a few irresponsible pet owners are to blame. And while the goldfish may have cost the owners a few dollars, this mess is going to cost the state an estimated $150,000 to try to remove these feral fish.

But this isn’t the only place this is happening. Goldfish are invading lakes and streams worldwide, and it’s all our fault.

If you think you’re doing the goldfish a favor by releasing it, you’re not! Instead, you’re setting the stage for an ecological disaster, which could threaten hundreds of other species. Turns out, goldfish are one of the world’s worst invasive species.

Goldfish were first selectively bred in China 2,000 years ago for food. By the 14th century, goldfish had been promoted from our meals to our entertainment. It wasn’t long before pet owners helped them spread across the world, eventually reaching North America by the 19th century.

They may look small and cute in your home, but in the wild it’s a different story. Given enough time and resources, these little orange monsters will grow into giants, reaching as much as 4 pounds, or 2 kilograms, about the size of an American football!

These big fish are also big eaters, feeding on plants, insects, crustaceans, and other fish. But they’re not just consuming what other fish rely on to survive – their voracious feeding time actually kicks up mud and sediment, which can lead to harmful algae blooms that choke the ecosystem.

If that’s not enough, they also introduce foreign parasites and diseases that wreak havoc on the delicately balanced ecosystems wherever they go. And they aren’t content to stay in one place. Goldfish are a rapidly reproducing fish and will migrate across multiple bodies of water. Case in point: When a few were dumped in a local Australian river in the early 2000s they eventually migrated to the Vasse River, where they’re still a major problem today.

There are similar accounts of goldfish invasions in Epping Forest, London; Alberta, Canada; and Lake Tahoe, Nevada. In fact, invasive fish species accounted for over half of the total fish population in Lake Tahoe Basin. Besides causing fiscal and environmental disasters there are other reasons you should keep that goldfish in its tank.

For starters, goldfish are smarter than you might think. They have a memory span of at least three months, which means you can teach them tricks like this. They also can tell the difference between Stravinsky and Bach.

Can you do that?

So, consider the wildlife, and think twice before tossing that goldfish away.

Additional video courtesy Spartan’s tricks.

EDITOR’S NOTE: This video was originally published in April 2018.

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What’s inside a blobfish, the ‘world’s ugliest animal’

  • The blobfish was crowned the world’s ugliest animal in 2013 — a title it still defends today.
  • But drop this fellow 9,200 feet below sea level, and the water holds up all that flab like a push-up bra, making the fish a little more handsome.
  • Between the skin and the muscles is a lot of fluid. And that’s the secret to the fish’s distinct appearance — and its survival.
  • Visit Business Insider’s homepage for more stories.

Following is a transcript of the video.

Narrator: This creature was crowned the world’s ugliest animal in 2013, a title it still defends today. On land, he’s got a body like Jell-O and a big old frown. But drop this fellow 9,200 feet below sea level, and the water holds up all that flab like a push-up bra, making the fish a little more handsome. Same old fish, but with a little more support. So, what is all that water pressure holding together?

David Stein: Between the skin, that flabby skin, and the muscles is a lot of fluid.

Narrator: This is David Stein, a deep-sea-fish biologist who was lucky enough to dissect 19 blobfishes in the 1970s. Blobfish look blobby because they are full of water. Under their skin, blobfish have a thick layer of gelatinous flesh that floats outside their muscles.

Stein: If you pick up a blobfish by the tail, then it kind of flows to the head.

Narrator: This water-filled, Jell-O-like layer allows the blobfish to stay somewhat buoyant, which is important because blobfishes don’t have a swim bladder.

Stein: And fishes that have swim bladders are able to adjust their buoyancy. They can secrete gas into the swim bladder or remove it. A fish that lives on the bottom doesn’t need to be able to maintain its buoyancy.

Narrator: So, the Jell-O layer isn’t a perfect substitute, but the blobfish doesn’t need to be a strong swimmer. The predator has a highly specialized hunting strategy that’s perfect for the rocky barrens of the deep sea.

Stein: It just sits there and waits for dinner to come by.

Narrator: If all you do is sit, you don’t need much under your skin. Just watery tissue, some yellow pockets of fat, and a smidgen of muscle. In case you hadn’t guessed, blobfishes aren’t exactly yoked. They have very little red muscle, the kind that allows you, a human, to run a mile or a tuna fish to migrate across oceans. Instead, blobfish have a lot of white muscle, which allows them to swim in short bursts and lunge at prey that on occasion ramble by.

This is a baby blobfish. It’s a cleared and stained specimen, meaning all its tissue has been dissolved to show only the bones and cartilage. Those thin red lines you see, they’re the blobfish’s bones dyed red. If you’re having trouble seeing the bones, you’re not the only one. Blobfish have poorly ossified skeletons, meaning they’re thinner and more fragile than the bones of most shallow-water fish. This is another handy deep-sea adaptation, as it takes a lot of precious energy to build strong bones.

But the blobfish saves its energy to develop what might be the most important bone in its body: its jaws, which also happened to be the reason it looks so gloomy. The fish needs enormous jaws so it can snap up any prey that passes by and swallow it whole, maybe even smacking its blubbery lips as it eats. And that brings us to its stomach. If you’re the kind of creature that eats anything that swims by, some surprising things can wind up in your stomach. Stein found a wide range of foods and not-foods in the blobfish he dissected. Fish, sea pens, brittle stars, hermit crabs, an anemone, a plastic bag, and also lots of rocks.

Stein: Their stomach contents kind of bear out the fact that they’re probably not too bright.

Narrator: He also found octopus beaks, the cephalopods’ hard, indigestible jaws. This means that one of the world’s flabbiest fishes has been able to eat one of the sea’s most cunning predators. If you’re surprised, just think about the blobfish’s thick skin. What would it be harder to grab in a fight: a sack of bones or a sack of Jell-O? Stein suspects it might be the latter.

Stein: If the skin is loose, perhaps the suckers can’t really get a good grip on it.

Narrator: Stein found sucker marks across the blobfish’s body, a hint that the fish might’ve been in some deep-sea fights. So while all of this Jell-O might look a little unconventional, well, it seems to have served its purpose. The blobfish is perfectly suited to life in the deep sea, where beauty standards are probably quite different. After all…

Stein: Ugly is kind of in the eye of the beholder.

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