8 Adorable Animals That Are Surprisingly Violent

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iStock

They're cute. They're cuddly. But beware: they're killers.

1. KOALAS

Young koala in a tree.
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It may seem hard to believe, but the world's most cuddly animal has a dark side. Most of the time, these tree-huggers keep to themselves, adhering to a strict schedule of snacking and snoozing (up to 22 hours a day). But sometimes, a koala snaps. Koala-on-koala violence is generally pretty mild, but they have been known to go after dogs and even humans.

For example: In December 2014, Mary Anne Forster of South Australia found herself at the receiving end of a vicious bite after trying to protect her two dogs from an aggressive koala. The koala sank its teeth into Forster's leg and refused to let go, relenting only after she reached into its mouth and pried its jaws apart with her hands. Forster then walked her dogs more than a mile back to her house before going to the hospital for stitches, proving that the only thing tougher than Australian wildlife is an Australian.

2. BEAVERS

Beaver in water looking at camera.
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They've got huge, razor-sharp teeth that never stop growing. They're fiercely territorial. They build complex underwater lodges with architectural precision. And, most importantly, they don't take crap from anybody. There was the fisherman in Belarus who died when a beaver bit through his femoral artery. There was the lake in an Alaskan dog park where angry beavers sent a half-dozen dogs to the emergency vet for stitches, prompting park officials to post signs reading "WARNING AGGRESSIVE BEAVERS ARE LIVING IN UNIVERSITY LAKE!"

And those are just the healthy, well-adjusted ones. Rabid beavers have gone after swimmers in Canada and the U.S., including an 83-year-old woman in Lake Barcroft, Virginia. "There is no way I will swim in that place again," she said after the incident.

3. COWS

Heck cattle and calf.
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Not all cows. But some cows. And those cows are terrifying. They're called Heck cattle, also known—and we are not making this up—as "Nazi Super Cows."

In the 1920s and '30s, German zoologists (and brothers) Heinz and Lutz Heck each sought to recreate the extinct wild ox called the aurochs, which featured heavily in Teutonic mythology. Heinz Heck chose Spanish fighting cattle as a breeding strain for their prehistoric shape and aggression, and the Nazis used their fierce image in propaganda. Then, World War II happened. The Nazis fell, but the uber-cows survived.

Heck cattle still roam Bavaria to this day and are available for purchase by those with a death wish. Farmer and photographer Derek Gow brought a herd of Heck cattle to his UK farm in 2009 and successfully bred them before realizing he was in over his head. "They would try to kill anyone," he told The Guardian of the dozen or so he had to put down because of the danger they posed. "Dealing with that was not a lot of fun at all."

4. DOLPHINS

Dolphin smiling in a pool.
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It sounds outrageous, but it's true: dolphins are actually pretty horrible.

Researchers have suspected as much since the 1990s, when the battered corpses of hundreds of porpoises and baby dolphins started washing up on both sides of the Atlantic. Eventually the researchers concluded that male dolphins were slaughtering other dolphins, including their own babies, just because they could [PDF].

This news was especially alarming to federal officials, who were concerned about human safety in the growing and unregulated industry of dolphin tourism. "It's a time bomb waiting to go off," said a spokeswoman for the National Marine Fisheries Service.

If that wasn't bad enough, dolphins have sexually assaulted divers and swimmers on numerous occasions, and have been known to play volleyball with helpless baby sharks.

5. PRAIRIE DOGS

Prairie dog eating in a field.
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Move over, dolphins: you’ve got competition for Most Horrifying Murder Spree. And prairie dogs, as it turns out, do not take kindly to competition. Researchers say white-tailed prairie dogs routinely hunt and slaughter ground squirrels, with which they compete for resources.

The prairie dogs are plant-eaters, so once they've bitten the squirrels to death, they just drop the carcasses and stroll away. The first time prairie dog expert John Hoogland saw it happen, he was shocked. "It boggles the imagination that something like that was going on under our noses and we didn't notice," he told New Scientist (which—be warned—includes Hoogland's gruesome images of the carnage in its story).

Unlike the murder-happy dolphins, however, the prairie dogs have a clear motivation. Prairie dog serial killers (that is, those that just kept killing) tend to have more babies than non-killers, and they and their offspring are more likely to survive.

"It begs the question of whether it's going on in other species," Hoogland said.

6. SLOW LORISES

Slow loris hiding behind a tree.
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After the dolphin, the slow loris looks like a saint. A shy, weird saint, with a mouth full of needle-like teeth and venomous elbows.

Yes, the slow loris has venomous elbows. When a loris feels threatened, it throws its arms over its head. This is adorable, but it's also strategic, giving the little primate an opportunity to lick the toxin-producing glands in its upper arms and fill its mouth with venom. While the venom itself is only strong enough to kill smaller animals, loris bites have sent humans—including one researcher—to the hospital in anaphylactic shock.

Some scientists argue that the loris's elbow grease isn't venom at all, and that its ability to kill is purely incidental. But … this is probably not much comfort to someone who's just been bitten.

7. SWANS

A swan swimming in green waters.
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Like most cows, most swans are fine. Sure, they get a bit territorial during breeding season, but who doesn't? But the swans that are not fine are really, really not fine.

Take Hannibal, the swan who killed 15 other swans and injured dozens more on the grounds of Pembroke Castle in Wales. Hannibal bit his victims, beat them with his wings, broke their toes, and held their heads underwater until they drowned. After each brutal attack, Hannibal would parade in front of his kill, displaying the carnage for his wife—Mrs. Hannibal—and cygnet.

And then there's Mr. Asbo, the swan that terrorized rowers on the River Cam in Cambridge for years. Mr. Asbo (short for "Anti-Social Behaviour Orders") regularly attacked and even capsized small boats before turning his aggression on larger vessels. Eventually, even the Royal Society for the Prevention of Cruelty to Animals (RSPCA) agreed that Mr. Asbo was "out of control" and got a license to relocate him and his mate to another county. One year later, a young male swan appeared in the same spot and started threatening people. Locals named the cocky newcomer Asboy, after his father.

8. HIPPOPOTAMUSES

Hippopotamus standing in the water.
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Each year, the humble hippopotamus kills more people than lions, tigers, or bears. Or sharks, for that matter. (In the hippo's defense, humans kill quite a lot of hippopotamuses. This is not cool.) They're intensely aggressive, which is a dangerous quality in an animal that can reach 17 feet long and 10,000 pounds. They're not slow, either: They can reach speeds of up to 30 miles per hour on land, outpacing even Olympian Usain Bolt. They go after each other, after humans, after crocodiles, and even after boats and cars, flipping the crafts and attacking the inhabitants. From time to time, someone will try to tame a hippo and keep it as a pet. This does not end well. Do not try this.

This story first ran in 2015.

Wednesday’s Best Amazon Deals Include Computer Monitors, Plant-Based Protein Powder, and Blu-ray Sets

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Amazon
As a recurring feature, our team combs the web and shares some amazing Amazon deals we’ve turned up. Here’s what caught our eye today, December 2. Mental Floss has affiliate relationships with certain retailers, including Amazon, and may receive a small percentage of any sale. But we only get commission on items you buy and don’t return, so we’re only happy if you’re happy. Good luck deal hunting!

11 Things You Might Not Know About Reindeer

Britain's only herd of free-ranging reindeer live in Scotland’s Cairngorms National Park.
Britain's only herd of free-ranging reindeer live in Scotland’s Cairngorms National Park.
Joe Green, Unsplash

Beyond their sled-pulling capabilities and discrimination against those with red noses, what do you really know about reindeer?

1. Reindeer and caribou are the same thing.

Historically, the Eurasian reindeer and American caribou were considered to be different species, but they are actually one and the same: Rangifer tarandus. There are two major groups of reindeer, the tundra and the woodland, which are divided according to the type of habitat the animal lives in, not their global location. The animals are further divided into nine to 13 subspecies, depending on who is doing the classification. One subspecies, the Arctic reindeer of eastern Greenland, is extinct.

2. Reindeer have several names.

Reindeer comes from the Old Norse word hreinin, which means "horned animal.” Caribou comes from Canadian French and is based on the Mi'kmaq word caliboo, meaning “pawer” or "scratcher," in reference to the animal’s habit of digging through the snow for food.

3. Santa’s reindeer are most likely R. tarandus platyrhynchus, a subspecies from Svalbard.

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Clement C. Moore’s poem, "A Visit from Saint Nicholas,” introduced the world to Santa’s reindeer and describes them as "tiny." The only reindeer that could really be considered tiny are the Svalbard subspecies, which weighs about half as much as most reindeer subspecies and are at least a foot shorter in length. That may prove useful when landing on roofs.

Strangely, you’ll almost never see these guys in depictions of Santa. Live-action films usually use full-sized reindeer and animations usually draw the creatures as a cross between a white-tailed deer and a reindeer.

4. It’s not always easy to tell the sex of a reindeer.

In most deer species, only the male grows antlers, but that’s not true for most reindeer. Although the females in certain populations do not have antlers, many do. During certain times of year, you can still tell the sex of a reindeer by checking for antlers. That’s because males lose their antlers in winter or spring, but females shed theirs in the summer.

5. Santa’s reindeer may or may not be female.

Since reindeer shed their antlers at different points of the year based on their sex and age, we know that Santa’s reindeer probably aren't older males, because older male reindeer lose their antlers in December and Christmas reindeer are always depicted with their antlers. Female Svalbard deer begin growing their antlers in summer and keep them all year. That means Santa’s sled either has to be pulled by young reindeer, constantly replaced as they start to age, or Santa’s reindeer are female.

6. Reindeer were originally connected to Santa through poetry.

Before Moore wrote “A Visit from Saint Nicholas” (a.k.a. “The Night Before Christmas”) in 1823, no one thought about reindeer in conjunction with Santa Claus. Moore introduced the world to Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Dunder and Blixem (the last two of which were later changed from Dutch to German, becoming Donner and Blitzen). While the first six names all make sense in English, the last two in German mean “thunder” and “flash,” respectively.

As for little Rudolph, he wasn’t introduced until catalog writer Robert L. May wrote a children’s book in verse for his employer, Montgomery Ward, in 1939 titled “Rudolph the Red-Nosed Reindeer.”

7. Reindeer are the only mammals that can see ultraviolet light.

Humans can see light in a range of wavelengths, from about 700 nanometers (in the red spectrum) to 400 nanometers (in the violet spectrum). Reindeer can see light to 320 nanometers, in the ultraviolet (UV) range. This ability lets reindeer see things in the icy white of the Arctic that they would otherwise miss—kind of like viewing the glow of a white object under a blacklight. Things like white fur and urine are difficult, even impossible, for humans to see in the snow, but for reindeer, they show up in high contrast.

8. Reindeer evolved for life in cold, harsh environments.

Geoffrey Reynaud/iStock via Getty Images

Life in the tundra is hard, but reindeer have it easy-ish thanks to their amazing evolutionary enhancements. Their noses are specially adapted to warm the air they breathe before it enters their lungs and to condense water in the air, which keeps their mucous membranes moist. Their fur traps air, which not only helps provide them with excellent insulation, but also keeps them buoyant in water, which is important for traveling across massive rivers and lakes during migration.

Even their hooves are special. In the summer, when the ground is wet, their foot pads are softened, providing them with extra grip. In the winter, though, the pads tighten, revealing the rim of their hooves, which is used to provide traction in the slippery snow and ice.

9. some reindeer migrate longer distances than any other land mammal.

A few populations of North American reindeer travel up to 3100 miles per year, covering around 23 miles per day. At their top speed, these reindeer can run 50 mph and swim at 6.2 mph. During spring, herd size can range from 50,000 to 500,000 individuals, but during the winter the groups are much smaller, when reindeer enter mating season and competition between the bucks begins to split up the crowds. Like many herd animals, the calves learn to walk fast—within only 90 minutes of being born, a baby reindeer can already run.

10. Reindeer play an important role in Indigenous cultures.

In Scandinavia and Canada, reindeer hunting helped keep Indigenous peoples alive, from the Mesolithic and Neolithic periods all the way through modern times. In Norway, it is still common to find reindeer trapping pits, guiding fences, and bow rests dating from the Stone Age. And in Scandinavia, reindeer is still a popular meat, sold in grocery stores in fresh, canned, and dried forms. Almost all of the animal’s organs are edible and many are crucial ingredients of traditional dishes in the area. In North America, Inuit rely on caribou for traditional food, clothing, shelter, and tools.

11. Reindeer used to live farther south.

Reindeer now live exclusively in the northern points of the globe, but when Earth was cooler and humans were less of a threat, their territory was larger. In fact, reindeer used to range as far south as Nevada, Tennessee, and Spain during the Pleistocene area. Its habitat has shrunk considerably in the last few centuries. The last caribou in the contiguous United States was removed to a Canadian conservation breeding program in 2019.

As for how Santa's nine reindeer manage to fly while pulling a sled carrying presents for every child in the whole world, science still hasn’t worked that out.