The Horrors of Anglerfish Mating

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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 following. 

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 six or seven 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.”

10 Terrifyingly Huge Birds You Should Know

AndreaWillmore/iStock via Getty Images
AndreaWillmore/iStock via Getty Images

They’re gigantic, they’re often defensive, and you wouldn’t want to run into them in a zoo after hours. Meet a few of the world’s biggest birds with attitude, from flightless giants to modern-day pterodactyls.

1. Ostrich

Everyone knows that the ostrich is the world’s biggest bird, weighing an average of 230 pounds and standing 7 feet tall (and some individuals can grow up to 9 feet). They can also chase you down: Ostriches are the fastest species on two legs, with a top speed of about 43 mph. They can maintain a swift 30 mph pace for 10 miles, making them the marathon champs of the avian world.

2. Southern Cassowary

Often called the most dangerous bird on Earth, in addition to being one of the planet’s biggest birds, the southern cassowary is roughly 150 pounds of mean. On each foot is a 5-inch claw that cassowaries use to defend themselves. At least two people have been kicked to death by cassowaries, the most recent being a Florida man who unwisely kept one of the birds as a pet.

3. Emu

Emu with eggs
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Like a smaller, shaggier ostrich, the 5- to 6-foot emu is the second-largest bird on Earth (as well as a goofy spokesbird for insurance). During the breeding season, female emus fight enthusiastically over unattached males. But the results of this mating ritual are impressive: clutches of forest-green, oval eggs that resemble giant avocados.

4. Greater Rhea

This flightless bird is named for the Titan goddess Rhea, who gave birth to all of the Olympian gods and goddesses in Greek mythology. At up to 5 feet tall and 66 pounds, the greater rhea may not seem like as much of a terror as the ostrich. But it gathers in massive flocks of up to 100 birds during the non-breeding season, so watch out if you happen to be in its South American habitat.

5. Dalmatian Pelican

Dalmatian pelicans
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How scary can a pelican be, you ask? When it stands almost 6 feet tall, weighs 33 pounds, and has a wingspan of 9 feet—all traits of the Dalmatian pelican—it's pretty petrifying. These scruffy-feathered monsters, native to Europe and Asia, breed in colonies of up to 250 pairs and can gulp impressive mouthfuls of fish in one go.

6. Mute Swan

One of the heaviest flying birds, mute swans look harmless as they glide over ponds, lakes, and rivers. But mute swans are far from silent when defending their families and territory. Male swans warn interlopers that they’re getting too close with a hiss, then can launch a straight-up assault, bashing the intruder with their wings. They’ll even attack kayakers, canoeists, and people just minding their own business.

7. Andean Condor

Andean condor
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This freakishly big vulture isn’t satisfied with just any carrion—it prefers large carcasses like cattle and deer for dinner. Maintaining its average weight of 25 pounds requires a lot of calories, after all. Its wingspan is slightly less than its northern cousin, the California condor, but it still reaches a dramatic 9 to 10 feet.

8. Cinereous Vulture

Another big bird with a 10-foot wingspan, this Old World vulture has excellent vision to spot carrion while it flies, and a featherless head that resists the accumulation of gore when it feeds. Though it’s intimidating to look at, the cinereous vulture plays an important role in its ecosystem by cleaning up roadkill and other dead animals.

9. Marabou Stork

Marabou stork
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As if its red-tinged wattle, black back, and dagger-esque bill weren’t alarming enough, the marabou stork is sometimes called the “undertaker bird” thanks to its Dracula-like appearance. It also eats other birds. The largest verified wingspan on a marabou stork measured 10.5 feet, though unverified reports cited a specimen with 13.3-foot span.

10. Shoebill

Shoebill storks may not be the tallest, heaviest, or widest-winged birds, but just look at that death stare. On top of having a nutcracker for a face, the 5-foot-tall shoebill leads a fearsome lifestyle. It stands absolutely still for hours to hunt prey, watching for lungfish or baby crocodiles, then spreads its wings and collapses over it while trapping the target in its bill.

Scientists Capture Video of Deepstaria, a Rarely Seen, Shapeshifting Jellyfish

OET/NautilusLive
OET/NautilusLive

Millions of years of evolution taking place beneath the sea's surface have produced some bizarre animals. Jellyfish are among the oldest—and strangest—of the bunch. Some have "transient" anuses that only form when necessary, and others can renew their life cycles indefinitely. Little is known about Deepstaria, a jellyfish recently spotted by the crew of the Nautilus research vessel in the central Pacific Ocean, but as the video below shows, it's no less unusual than other species of jellyfish.

As Live Science reports, scientists aboard the Nautilus were scanning the seafloor about halfway between the U.S. and Australia when they spotted a spooky-looking creature hovering in front of them. It soon became clear that cosplaying a ghost wasn't all it could do. The jelly unfurled its sheet-like bell to reveal a geometric mesh membrane used to distribute nutrients throughout its body—a telltale sign of Deepstaria. It spends the rest of the video putting on a show for its guests, transforming from something resembling a crumpled plastic bag to a billowing blanket shape.

Deepstaria enigmatica was discovered by the Jacques Cousteau-designed Deepstar 4000 submersible—the vessel the species is named after—in the 1960s. It's only been spotted about a dozen times in the years since, and many details of how it lives remain a mystery to researchers.

Deepstaria's most distinctive feature is its massive, flowing bell. It lacks the tentacles most jellyfish use to wrangle prey, and scientists suspect it instead uses its bell as a net when hunting. The specimen captured in this video appears to be harboring a stowaway: a bright-red, living isopod suspended inside the bell. It isn't clear if the creature hitched a ride on purpose to evade more ferocious predators, if it's some type of parasite, or if it's the jellyfish's lunch.

With so many undiscovered and understudied species living in the sea, the Nautilus research vessel is frequently stumbling upon extraordinary examples of ocean life. In 2016 alone, it recorded footage of a googly-eyed stubby squid and a mysterious purple orb.

[h/t Live Science]

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