11 Fascinating Facts About the Frilled Shark

Sometimes called a “living fossil” because it has changed so little since prehistoric times, the eel-like frilled shark—which is rarely seen by humans—has been in the news this week after a snake-like one was found off the coast of Portugal. Here’s a quick primer.

1. IT’S NAMED FOR ITS GILLS.

Its scientific name is Chlamydoselachus anguineus, but this creature’s common name comes from its gills: Unlike all other sharks, which have separate gills, C. anguineus’ first pair of gills go all the way across its throat; each pair is lined at the edges with red “fringe.”

2. IT WAS DISCOVERED IN THE 19TH CENTURY.

The sharks were first scientifically described by German ichthyologist Ludwig H.P. Döderlein, who taught at Tokyo University from 1879 to 1881 and brought two specimens captured in Tokyo Bay when he returned to Vienna. His paper describing the sharks was lost, however, so the first description comes from Samuel Garman in the 1884 edition of the Bulletin of Essex Institute. In the remarks after the description, Garman noted that

Such an animal as that described is very likely to unsettle disbelief in what is popularly called the “sea serpent.” Though it could hardly on examination be taken for anything but a shark, its appearance in the forward portion of the body, particularly in the head, brings vividly to mind the triangular heads, deep-cleft mouths, and fierce looks of many of our most dreaded snakes. In view of the possible discoveries of the future, the fact of the existence of such creatures, so recently undiscovered, certainly calls for a suspension of judgment in regard to the non-existence of that oft-appearing but elusive creature, the serpent-like monster of the oceans.

The frilled shark’s species name, anguineus, is Latin for “consisting of snakes” or “snaky.”

Biologist David A. Ebert, director of the Pacific Shark Research Center, described a second frilled shark species—Chlamydoselachus africana, which lives off the coast of Africa and is about half as long as its predecessor—in 2009.

3. IT’S GOT INSANE TEETH.

The frilled shark’s mouth is just as terrifying as the maw of a great white: It’s lined with 25 rows of backward-facing, trident-shaped teeth—300 in all. “The teeth are constructed for grasping and from their peculiar shape and sharpness it would seem as if nothing that once came within their reach could escape them,” Garman wrote. “Even in the dead specimen the formidable three-pronged teeth make the mouth a troublesome one to explore.” 

Ebert can testify to that fact. “I can tell you from snagging my fingers on the teeth, you can only back out one way and that’s in toward the mouth and then out,” he told WIRED. “It didn’t feel good, I can tell you that.” The shark uses the bright white teeth, which sharply contrast against its brown body, to lure in prey: “By the time [the prey] realize, Oh, that’s the teeth of a shark, they’re too close and the shark is able to ambush them at that point,” Ebert said. “It’s almost like when you drive out of a parking lot exit and they have the spikes sticking out that say, ‘Do not back up.’ That’s kind of what happens when these things catch prey items.”

And as if its teeth weren’t freaky enough, the frilled shark has spines, called dermal denticles, lining its mouth. So if you happen to see one of these anywhere, it’s better to look and not touch.

4. IT “HOVERS” IN THE WATER...

Scientists once believed that the frilled shark wriggled through the water like an eel. But according to the ReefQuest Centre for Shark Research, “its body cavity is elongate and packed with a huge liver perfused with low-density oils and hydrocarbons, making the shark almost neutrally buoyant at depth.”

5. … AND IT MAY STRIKE AT ITS PREY LIKE A SNAKE.

No one has ever observed the frilled shark hunting, but scientists believe that it uses its posterior fins as propulsive surfaces to launch itself at its prey. Its long jaws, which terminate at the back of its head, may allow the animal to gape extra wide and take in prey half as long as its body. Analysis of the stomach contents of captured specimens has revealed that the frilled shark’s diet is 61 percent cephalopod, 11 percent teleost fishes, and, occasionally, other sharks.

6. IT’S FOUND ALL OVER THE WORLD—BUT YOU PROBABLY WON’T SEE IT.

The Food and Agriculture Organization of the United Nations notes that the frilled shark is “wide-ranging but spottily distributed”; you can see where the shark is found on the map above. It typically resides in depths between 390 and 4200 feet, so people rarely see these sharks unless they venture to the surface, which isn’t unheard of (as you’ll see below).

7. FEMALES ARE BIGGER THAN MALES.

On average, males range from 3.2 to 3.6 feet and females from 4.4 to 4.9 feet; the maximum these sharks can reach is 6.4 feet.

8. THEIR GESTATION PERIOD MAY BE 3.5 YEARS LONG.

A study of frilled sharks in Japan revealed that the animals breed year-round; litters typically consist of six pups, which emerge from eggs while still in the mother’s uterus and are then born live. Scientists think the shark may have the longest gestation period ever: Frilled sharks could gestate for as long as 42 months, nearly twice as long as African elephants carry their young. Scientists theorize that the extreme length has something to do with the shark’s cold deep sea habitat.

9. IT WASN’T SEEN IN ITS NATURAL HABITAT UNTIL 2004.

NOAA scientists exploring the “Latitude 31-30 Transect” in the Atlantic Ocean captured a video of a frilled shark “swimming over sea bottom that was covered with tiny sand dunes” during a submersible dive. “This species has been, on rare occasion, caught or taken in bottom trawls,” the site notes. “To the knowledge of everyone on board, however, this was the first time anyone had ever seen the rare species in its natural habitat.”

10. ONE WAS CAPTURED IN JAPAN IN 2007.

In January 2007, a Japanese fisherman spotted a strange, eel-like creature with a mouth full of sharp teeth near the surface; he alerted the staff of the Awashima Marine Park in Shizuoka, who captured the animal and transferred it to a seawater pool, where they filmed it. “We think it may have come close to the surface because it was sick, or else it was weakened because it was in shallow waters,” a park official said. “We believe moving pictures of a live specimen are extremely rare. They live between 600 and 1000 meters under the water, which is deeper than humans can go.” The shark, a female, died a few hours after its capture.

11. IT CALLS ANOTHER FREAKY SHARK ITS COUSIN.

The frilled shark might have rows upon rows of gnarly teeth, but its cousin, the goblin shark, can thrust its jaw out of its face. Which is more terrifying?

The Poison-Detecting Secret Weapon of the Middle Ages: Unicorn Horn

A woodcut of a unicorn from 1551
A woodcut of a unicorn from 1551

In the Middle Ages and into the Renaissance, Europeans knew that unicorns were real. After all, their horns were the treasured possessions of royalty, nobility, and even clergy. Charles VI of France had one, as did Lorenzo de Medici, and Danish rulers sat on a throne carved out of them. Queen Elizabeth I had a fully intact horn she used as a scepter; it was valued at 10,000 pounds—roughly the cost of a castle in her day. In fact, unicorn horns were considered so valuable the Elizabethan dramatist John Dekker wrote that one was "worth a city."

But unicorns horns weren't prized just for their beauty or rarity, or as tokens of extreme wealth. They were believed to be powerful defense against disease—and poison.

Fierce But Pure

Oil painting of a woman and unicorn by a follower of Timoteo Viti
Chastity, oil painting by a follower of Timoteo Viti

For an animal that never existed, the unicorn got around. The ancient myths of India and China mention unicorn-like animals, as did the tales Greek travelers brought back from India and other far-flung lands. The earliest Greek description is from the historian Ctesias, who wrote around 400 BCE of a large, agile animal with a white body, dark red head, and a long horn on its forehead. About a hundred years later, scholars translating the Old Testament interpreted a horned animal known in Hebrew as re'em as a unicorn (though modern translators prefer the term auroch, an extinct species of cattle). Writing in the first century CE, Pliny the Elder described the unicorn is "the fiercest animal, and it is said that it is impossible to capture one alive. It has the body of a horse, the head of a stag, the feet of an elephant, the tail of a boar, and a single black horn three feet long in the middle of its forehead.”

From the beginning, accounts of the unicorn emphasized their healing and purifying properties. Ctesias wrote, "Those who drink out of these horns, made into drinking vessels, are not subject, they say, to convulsions or to the holy disease [epilepsy]. Indeed, they are immune even to poisons if, either before or after swallowing such, they drink wine, water, or anything else from these beakers." Similar accounts appeared for centuries: Around the 3rd century CE, the Greek intellectual Philostratus wrote that "the Indians make drinking-cups from this horn, which have such virtue that the man who drinks from one will for one whole day neither fall ill, nor feel pain if wounded, nor be burned by passing through fire, nor even be affected by poisons which he could not swallow at any other time without harm."

By the 12th century, a German nun known for her saintly visions, Hildegard of Bingen, recommended a paste of powdered unicorn liver and egg yolk as a cure for leprosy, although she conveniently noted that it could fail if the "leper in question happens to be one whom death is determined to have or else one whom God does not wish to be cured." Unicorn hide was also recommended in boots and belts, partly as prevention for that greatest scourge of the Middle Ages: plague.

Belief in the healing powers of the unicorn focused especially on its mysterious, twisting horn. The substance, often called alicorn, was associated with great purity as well as healing, sometimes with religious overtones (the purity of the white animal was thought to be connected to Jesus Christ, and the horn to his cross). Hunters in search of a unicorn were supposed to lure the animal with a female virgin, capturing the animal once it fell asleep in her lap.

A Common Deception

Narwhal tusk
A narwhal tusk

Of course, no such hunters were ever successful. Objects portrayed as being made from unicorn sometimes came from rhinoceroses or mammoth fossils but most often in Europe from narwhals, which were hunted by the Vikings in the North Atlantic. The Vikings harvested the narwhals’ spiraling tusks and sold them on to traders who either didn't know, or didn't care, about their true origins in the sea.

Once obtained, alicorn could be taken in many forms. Powdered, it was applied to dog bites and other wounds or consumed as treatment for plague, gout, and other diseases. The influential German physician Johann Schröder recommended it for childhood epilepsy. And although other physicians numbered among the earliest skeptics, apothecaries used unicorns widely in their potions. Eau de licorn—water purified by the introduction of unicorn’s horn or by being poured through a hollowed-out segment of horn—was also widely sold and reputed to have health benefits.

While the extraordinary cost of the intact horns made them showpieces for the rich, powdered unicorn horn was an affordable remedy for the average citizen. This was largely because other substances could be easily substituted: horse hoofs, fossils, and other types of horn. In fact, the widespread problem of fraud led to frequent tests of the authenticity of the horn itself, including presenting it to spiders and scorpions and observing to see if they avoided it or died. If they did, the item was thought to be genuine horn.

Poison-Proof

A page from a 17th-century French medical text discussing unicorns
A page from a 17th-century French medical text discussing unicorns

Poisoning was particularly feared during the Middle Ages and into the Renaissance by the back-stabbing royalty and nobility keen to maintain their positions, not to mention their lives. Such an insidious crime required extraordinary measures: While European royalty kept other poison-detectors, including rubies, bezoar stones, and griffin claws, unicorn horn was a favored material for protection as well.

Whole unicorn horns were deployed on dining tables as poison detectors, while fragments of horn, called touches by the French, could be touched or dipped to plates of food to detect the presence of toxins. They could also be hung on chains or mounts of precious metal (actually less valuable materials, pound for pound, than the horn itself). French royalty had utensils made with alicorn, while other members of the European nobility had the horn inset into jewelry. The horn was expected to provide an alert to the presence of poison by changing color, sweating beads of moisture, or actually steaming. Alicorn might also be dipped into water or run over the actual linens and wall hangings in a banquet hall. Goblets fashioned from unicorn horn were also made across the continent; some believed these would shatter upon contact with a contaminated beverage.

While some medical writers, such as the famed French surgeon Ambroise Paré, were skeptical of the powers of the unicorn horn, many others believed in its merits. The Italian scholar and naturalist Andrea Bacci wrote a defense of the horn's use in 1573, telling the story of a man who consumed a poisoned cherry but was saved thanks to unicorn horn dissolved in wine. He also described an experiment in which two pigeons were fed arsenic, but the one who was given some scrapings of unicorn horn recovered and lived. The other died two hours after being fed the toxin [PDF].

But by the 17th century, the myth of the unicorn had begun to tarnish. European travelers to the Arctic brought back tales of the living narwhal, and further missions to other continents disproved the existence of unicorns by process of elimination, since no such animal was ever sighted. In July 1661, the men of the newly formed Royal Society put unicorn horn to the test: They placed a spider in a circle of powdered unicorn’s horn to see what would happen. From from being repelled by the horn, as writers had long claimed, the spider immediately scurried across the powder to escape. The men repeated the experiment several times, each with the same results. Their trial helped sound the death knell for credulous belief in the magical properties of unicorn horn.

The loss of value resulted in the disappearance or destruction of many precious specimens. Items once said to be made from unicorn horn are still in some museum collections, and very occasionally turn up for sale—still bearing their historical value, though no longer imbued with the mysterious properties that once made them worth a city or a castle.

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