The Horrors of Anglerfish Mating

Masaki Miya et al. "Evolutionary history of anglerfishes (Teleostei: Lophiiformes): a mitogenomic perspective," BMC Evolutionary Biology 10, article number: 58 (2010), Wikimedia Commons // CC BY 2.0
Masaki Miya et al. "Evolutionary history of anglerfishes (Teleostei: Lophiiformes): a mitogenomic perspective," BMC Evolutionary Biology 10, article number: 58 (2010), Wikimedia Commons // CC BY 2.0

When you think of an anglerfish, you probably think of something like the creature above: Big mouth. Gnarly teeth. Lure bobbing from its head. Endless nightmares. 

During the 19th century, when scientists began to discover, describe, and classify anglerfish from a particular branch of the anglerfish family tree—the suborder Ceratioidei—that’s what they thought of, too. The problem was that they were only seeing half the picture. The specimens that they were working with were all female, and they had no idea where the males were or what they looked like. Researchers sometimes found some other fish that seemed to be related based on their body structure, but they lacked the fearsome maw and lure typical of ceratioids and were much smaller—sometimes only as long as 6 or 7 millimeters—and got placed into separate taxonomic groups.

It wasn’t until the 1920s—almost a full century after the first ceratioid was entered into the scientific record—that things started to become a little clearer. In 1922, Icelandic biologist Bjarni Saemundsson discovered a female ceratioid with two of these smaller fish attached to her belly by their snouts. He assumed it was a mother and her babies, but was puzzled by the arrangement.

“I can form no idea of how, or when, the larvae, or young, become attached to the mother. I cannot believe that the male fastens the egg to the female,” he wrote. “This remains a puzzle for some future researchers to solve.”

When Saemundsson kicked the problem down the road, it was Charles Tate Regan, working at the British Museum of Natural History in 1924, who picked it up. Regan also found a smaller fish attached to a female ceratioid. When he dissected it, he realized it wasn’t a different species or the female angler’s child. It was her mate.

The “missing” males had been there all along, just unrecognized and misclassified, and Regan and other scientists, like Norwegian zoologist Albert Eide Parr, soon figured out why the male ceratioids looked so different. They don’t need lures or big mouths and teeth because they don’t hunt, and they don’t hunt because they have the females. The ceratioid male, Regan wrote, is “merely an appendage of the female, and entirely dependent on her for nutrition.” In other words, a parasite.

When ceratioid males go looking for love, they follow a species-specific pheromone to a female, who will often aid their search further by flashing her bioluminescent lure. Once the male finds a suitable mate, he bites into her belly and latches on until his body fuses with hers. Their skin joins together, and so do their blood vessels, which allows the male to take all the nutrients he needs from his host/mate’s blood. The two fish essentially become one.

With his body attached to hers like this, the male doesn't have to trouble himself with things like seeing or swimming or eating like a normal fish. The body parts he doesn’t need anymore—eyes, fins, and some internal organs—atrophy, degenerate, and wither away, until he’s little more than a lump of flesh hanging from the female, taking food from her and providing sperm whenever she’s ready to spawn.

Extreme size differences between the sexes and parasitic mating aren’t found in all anglerfish. Throughout the other suborders, there are males that are free-swimming their whole lives, that can hunt on their own and that only attach to the females temporarily to reproduce before moving along. For deep-sea ceratioids that might only rarely bump into each other in the abyss, though, the weird mating ritual is a necessary adaptation to keep mates close at hand and ensure that there will always be more little anglerfish. And for us, it’s something to both marvel and cringe at, a reminder that the natural world is often as strange as any fiction we can imagine.

Naturalist William Beebe put it nicely in 1938, writing, “But to be driven by impelling odor headlong upon a mate so gigantic, in such immense and forbidding darkness, and willfully eat a hole in her soft side, to feel the gradually increasing transfusion of her blood through one’s veins, to lose everything that marked one as other than a worm, to become a brainless, senseless thing that was a fish—this is sheer fiction, beyond all belief unless we have seen the proof of it.”

Amazon's Best Black Friday Deals: Tech, Video Games, Kitchen Appliances, Clothing, and More

Amazon
Amazon

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Black Friday is finally here, and Amazon is offering great deals on kitchen appliances, tech, video games, and plenty more. We will keep updating this page as sales come in, but for now, here are the best Amazon Black Friday sales to check out.

Kitchen

Instant Pot/Amazon

- Instant Pot Duo Plus 9-in-115 Quart Electric Pressure Cooker; $90 (save $40)

- Keurig K-Cafe Special Edition; $190 (save $30)

- Ninja OS301 Foodi 10-in-1 Pressure Cooker and Air Fryer; $125 (save $75)

- Nespresso Vertuo Next Coffee and Espresso Machine by Breville; $120 (save $60)

- KitchenAid KSMSFTA Sifter with Scale Attachment; $95 (save $75)

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Home Appliances

Roomba/Amazon

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Video games

Sony

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Computers and tablets

Microsoft/Amazon

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Tech, gadgets, and TVs

Apple/Amazon

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Headphones and speakers

Beats/Amazon

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Movies and TV

HBO/Amazon

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Toys and Games

Amazon

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Furniture

Casper/Amazon

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Beauty

Haus/Amazon

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Clothes

Ganni/Amazon

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- The Drop Women's Maya Silky Slip Skirt; $36 (save $9)

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Watch: In 1948, Idaho Officials Sent 76 Beavers Parachuting Into Idaho’s Wilderness

A young beaver with all four feet firmly on the ground.
A young beaver with all four feet firmly on the ground.
yrjö jyske, Flickr // CC BY 2.0

When people started building up the area around Idaho’s Payette Lake after World War II, its original residents began interfering with irrigation and agricultural endeavors. They weren’t exactly staging an organized protest—they were just beavers doing what beavers do.

Nevertheless, officials at the Idaho Department of Fish and Game decided their best bet was to find a new home for the long-toothed locals. The surrounding wilderness provided plenty of options, but transportation was another issue entirely. Traversing the undeveloped, mountainous terrain would require both trucks and pack animals, and experts knew from past relocation efforts that beavers weren’t fond of either.

“Beavers cannot stand the direct heat of the sun unless they are in water,” department employee Elmo W. Heter explained in a 1950 report [PDF]. “Sometimes they refuse to eat. Older individuals often become dangerously belligerent ... Horses and mules become spooky and quarrelsome when loaded with a struggling, malodorous pair of live beavers.”

To keep Payette Lake’s beavers healthy and happy during the journey, their human handlers would need to find another method of travel. As Boise State Public Radio reports, that’s when Heter suggested making use of their leftover WWII parachutes.

Two beavers would sit inside a wooden box attached to a parachute, which could be dropped from an airplane between 500 and 800 feet above their new home in the Chamberlain Basin. The cables that fastened the box to the parachute would keep it shut during the flight, but they’d slacken enough for the beavers to open the box upon landing. After testing the operation with weights, Heter and his colleagues enlisted an older beaver named Geronimo for a few live trials.

“Poor fellow!” Heter wrote. “You may be sure that ‘Geronimo’ had a priority reservation on the first ship into the hinterland, and that three young females went with him.”

Once Geronimo had certified the safety of the mission, the team began migrating the whole beaver population. During the fall of 1948, a total of 76 beavers touched down in their new territory. It wasn’t without tragedy, though; one beaver fell to his death after a cable broke on his box. Overall, however, the venture was deemed much safer (and less expensive) than any trip on foot would have been. And when department officials checked in on the beavers a year later, they had already started improving their ecosystem.

“Beavers had built dams, constructed houses, stored up food, and were well on their way to producing colonies,” Heter wrote. As Idaho Fish and Game’s Steve Liebenthal told Boise State Public Radio, the area is now part of “the largest protected roadless forest” in the continental U.S.

You can watch the Idaho Fish and Game Commission’s full 14-minute documentary about the process below.

[h/t Boise State Public Radio]