Nature
A Natural History of Sharks
Ancient fossils, diverse shark folklore, and why these friendly fish are in more danger than you are
Deep black eyes searching in the night, hunting prey with keen senses and sleek fins. Large, gaping mouths that only scoop up marine plankton. Pop-culture terrors. Protector-gods. Miniature predators only 20 centimeters long. And a Super Bowl dancer who just can’t seem to get their routine back on track.
Sharks — with their Jaws baggage and Shark Week sensation — are a diverse bunch. With over 1000 species of sharks and rays in the wild and 143 species listed as “vulnerable” or “endangered,” it’s difficult to say that sharks are the fearsome predators we make them out to be. They are at once majestic, powerful, and very, very old. But they are also derpy. Skittish. And in need of our help.
Working at my local aquarium, I watch visitors interact with the sharks in our touch tank display. Some have no problem reaching their hands in the water, ready to greet the horn sharks and swell sharks within. Some even need reminders to be gentle — these are still wild animals, after all. But others shy away, unable to bring themselves close to the water’s edge.
Almost everyone lingers a while at the shark tanks. They watch sharks slice through the water. And they ask questions.
Do they bite?
How do they hunt?
How old do they grow?
Why is their skin so rough?
Do people eat sharks? Is that safe?
Why doesn’t the aquarium have a great white shark?
Should we be afraid of megalodons? Do they even still exist?
No one yet has asked me about shark folklore, but any history of sharks must include tales from around the world that shape our perceptions of these big fish, with their dual nature as regal predators and villainized pop culture icons.
But as with any history, we should start at the beginning.
The VERY beginning.
What even IS a shark?
Unsurprisingly, one major theme surrounding sharks is their teeth. Sharks use jagged rows of teeth that fall out as they swim and eat. Their rough skin also gets its name from ‘teeth,’ because under a microscope, shark skin is made up of tiny plates that look like rows of teeth or dermal denticles.
These calcium phosphate teeth may be the only structures on a shark resembling bones, because the rest of the shark’s body is made out of cartilage. These teeth are often the only information left in shark fossils, the only window into sharks’ long past.
Sharks share the five senses we use every day: they see with deep black eyes suited to nighttime forays. They use their keen sense of smell detect fish oils in the water. Their ears are two tiny holes in the sides of their head. But sharks also use a sixth sense, electroreception. Using oily pores called the Ampullae of Lorenzi on their snout, sharks scope out prey’s electromagnetic fields and use the surrounding ions to target their meal’s every move.
Sharks are related to skates and rays. Some give birth to live young, while others hatch from eggs. These creatures take a LONG time to mature.
And they have been around for a very long time.
Older than trees, older than the dinosaurs
Sharks are ancient beings. They evolved over 400 million years ago during the Paleozoic era, but sadly none of these sharks are alive today. Modern-day sharks evolved during the Mesozoic era. Sharks’ wide diversity and strong immune systems allowed them to survive five mass extinctions. The most recently evolved, the Hammerhead shark, arose during the Cenozoic or the modern era.
The Discovery Channel spends a large part of Shark Week fear-mongering and speculating whether extinct Megalodon sharks still roam the deep ocean. While huge sharks do exist, a Megalodon shark wouldn’t have enough food or the right climate to have survived past the Pliocene or 2.6 million years ago.
Today, scientists determine the age of fossils using radiocarbon dating. But they can also determine the age of modern sharks by determining the amount of radiocarbon leftover from nuclear bomb testing in the 1950s and 1960s. It’s because of this method that we now know that species like the Greenland Shark can live to become 400 years old, or that whale sharks live over 100 years.
As a species, sharks have withstood the test of time. But they are still vulnerable to changes that happen too quickly, and intense hunting that occurs too fast for populations to rebound. There are currently around 1000 species of sharks and rays, but many of these species are threatened by human activity.
Shark superpowers
Sharks lose their teeth ALL. THE. TIME. To compensate for this, they keep thousands of teeth inside their skull to replace the chompers they lose eating or fighting.
We’ve already learned that sharks detect electromagnetic fields. They do this using the Ampullae of Lorenzi and their lateral line system, sensory organs that help many fish determine pressure changes in the water. But since larger sharks often eat smaller sharks — even smaller sharks of the same species — this superpower can often turn against shark pups attempting to avoid electromagnetic detection.
Before they even hatch, baby sharks know how to sense predators who might use their movement against them. A developing shark embryo can sense predators and slow its movements to avoid detection deep inside its egg case.
While sawfish are not technically sharks (they belong to the ray family) these threatened species grow strong, sharp rostrums that they use to stun prey.
Shortfin mako sharks are the fastest sharks around. They can swim 25–46 mph and even breach the surface of the water, which makes them seem as if they were flying.
And if flying sharks don’t impress you, I’m not sure anything will.
What is a Shark Cafe?
For years, scientists have tracked shark migrations around the globe. Whale sharks gather to feast on plankton in South America and blacktip sharks spend their winters near Florida’s sunny shores. It’s because sharks have such large range that larger species such as great white sharks cannot be successfully raised or held in captivity.¹
But even though researchers understood the movement of great white sharks toward the Shark Cafe before winter, they did not yet understand why the sharks bobbed up and down in the water throughout the day, or why they traveled to that spot in particular. On satellite images, the Shark Cafe looked barren, a parcel of desert ocean in the middle of the Pacific.
But after visiting the Shark Cafe, scientists discovered that this daily up-and-down movement through the water column was another type of vertical migration for the sharks. During the day, the ocean looks barren, and male sharks dive deep during their rest period. But at night, the ocean comes alive, and the surface teems with food to feed these great whites through the winter.
The White Shark Cafe has been recommended as a UNESCO World Heritage Site because it is so biologically important for the sharks who travel there throughout the year. With so many threats already facing sharks, it is important to protect areas with such high concentrations of this vulnerable species.
Sharks in pop culture and folklore
Sharks feature in a lot of critical pop culture moments. There are, of course thrillers like Jaws, The Meg, and Sharknado which lead viewers to fear sunny beaches (that is, until you learn that the shark robot used in Jaws malfunctioned so often that Steven Spielberg needed to only show short clips of the creature to make his signature film.)
Sharks also lend their likeness to the ABC reality TV show Shark Tank, where the sharks in question are billionaires and potential investors in contestants’ start-ups. And the 2015 Super Bowl’s Left Shark reminds us that sometimes, it is 100 percent okay to mess up our entire dance number on live television.
But long before we associated sharks with treacherous waters, choosy billionaires, or Discovery Channel misdirection, there were other shark tales about their roles as protectors, tricksters, and monsters of the deep.
Japanese creatures called Isonade drag fishing boats to their death using their jagged tails, and the Bahaman sea monster Lascu is a wrathful creature often depicted as half-shark, half-octopus. In Greece, the shark sea monsters Cetus, Akhelios, and Lamia are all scary enough to warrant caution. But other shark myths depict protective shark deitiesthat help sailors survive the unpredictable sea.
In Fiji, the god Dakuwaqa often protected fishermen from danger on the sea, but he also lost a fight with an octopus goddess — a clear sign that no one should mess with cephalopods, even if you’re used to being the top predator of the ocean floor.
In Hawaii, there are over 40 native shark species and at least nine shark gods, but the god Kamohoali’l and goddess Ka’ahudahau are both protectors of fishermen and sailors. Kuhaimoana is another benevolent (giant) shark that ensures healthy catches at sea, and Kane’i’kokala saves shipwreck victims. There are also evil sharks and morally grey shark gods. Kane’apua is a Hawaiian trickster shark god whose actions sometimes result in others’ deaths.
Tanzania also warns of trickster sharks in the folk tale The Monkey and the Shark and the Washerman’s Donkey. According to one retelling, a shark fools a monkey into riding on its back to a feast, where the Monkey’s heart will be roasted to heal the king. The monkey claims that he forgot his heart back home, and when the pair return to retrieve it, the Monkey disappears into his tree. The moral of the story? You should never trust a shark or a monkey.
For more shark folklore (but with happy endings,) read the Maori myth of Kawariki and the Shark Man or the Hawaiian story The Shark that Came for Poi.
Why are sharks in danger today?
Over 100 million sharks are killed every year, not counting those killed from illegal fishing. According to the International Union for Conservation of Nature (IUCN) Red List criteria, one-quarter of all sharks are threatened with extinction. Why should we be concerned?
Sharks grow extremely slowly. They have long pregnancies and don’t reproduce every year. Both smaller horn sharks and great white sharks gestate for around 9-12 months. Whale shark gestation is not well documented, but some sources suggest that pregnancies in these animals might last three years. Then sharks need several more years — and sometimes decades, to reach sexual maturity. Greenland sharks don’t mature enough to give birth until they are over 150 years old!
Yet shark finning for tasteless shark fin soup, and fishing for shark livers, meat, gill plates, jaws, skin and leather kills sharks much faster than these species are able to rebound. Large shark abundance decreased by 21% large-scale fishing attacked populations in the 1950s. Sharks also face threats from climate change and pollution.
Some legislation is helping to slow shark fishing, but we need to take bold action. The US Shark Finning Prohibition act (2000) and the Shark Conservation Act (2011) are a good start to criminalizing the sale of illegal shark products in the US, but these acts are difficult to enforce.
Businesses have stepped up to prevent shark products. Some airlines have banned the transportation of shark fins and education outreach has decreased the popularity of shark fin soup, a delicacy that dates back to 1000 CE China. But shark finning is still an extremely lucrative business, and more needs to be done to protect these vulnerable creatures.
Another hidden threat to sharks is the wider fishing industry. Modern fishing techniques create a lot of bycatch, or unintended and unused fish caught during commercial fishing. This means that any wild fish caught using unsustainable practices may have led to the death of many larger species that were not part of the intended catch. These creatures are often killed and thrown overboard, creating a larger commercial fishing practice that is unsustainable and unethical. Eating farmed fish and shellfish or choosing sustainably-caught varieties may help reduce shark deaths and bycatch as a whole.
You can learn more about endangered shark species and shark protections here.
How can we protect sharks?
Learning about sharks is a great way to dispel myths that maintain the image of sharks as dangerous creatures that should be hunted out of existence. If you want to learn even more about sharks, listen to this episode of Ologies with host Alie Ward with shark researcher Chris Lowe, a leading shark expert.
Sharks are also extremely sensitive to pollution and climate change. Climate change is changing the migration patterns and population sizes of sharks’ prey. Sharks are moving north into colder waters as temperatures soar, and sharks are abandoning historic feeding areas for more suitable areas.
Pollution leads to shark entanglement and death. Sharks may eat plastic, mistaking small particles for fish, or they may suffer from chemical pollutants in the water that make it impossible to live near large cities or waterfront facilities (like desalination plants.)
There are a few organizations rallying for stronger shark protections. The nonprofit Shark Allies offers petitions and resources to learn more about shark overfishing and what you can do to stop this practice. One problem in the shark trade is that there are not enough ways to trace where sharks are caught and where these products go after processing. Shark meat has been found in pet food under the guise of “fish,” “white fish” and many other monikers. Right now, the only way to be sure your pet food isn’t abusing sharks is to avoid these vague ingredients altogether.
And of course, you can help sharks by avoiding shark products, including tourist items like shark jaws and shark teeth.
Sharks face more danger from humans than we face from them, but it’s important to realize that part of the problem lies in the misconception that sharks are fierce creatures with unrelenting bloodlust. In most cases, that simply isn’t true.
Working at the aquarium, I watch the horn sharks and swell sharks in the touch tanks nuzzle visitors’ hands. They bob their heads above the water looking for food. Admit it — they’re adorable. And yet they are still wild animals. But perhaps we can learn to look at sharks the same way we look at whales or dolphins: majestic, wacky creatures who need our help.
[1] Note: some wealthy individuals have tried to keep smaller sharks as pets. Please don’t do that. Here’s why.
