Looks can be deceiving and these 8 animals might appear innocent and cute, but they are surprisingly dangerous. However, it shouldn’t be that surprising as almost every wild creature has developed some defense mechanisms to protect themselves from predators.

Check them out and tell us what you think!

KOALAS

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 is aggressive. Koala-on-koala violence is mild, but they have been known to go after dogs and even humans.

BEAVERS

They’ve got huge, razor-sharp teeth that never stop growing. They’re fiercely territorial. Beavers build complex underwater lodges with architectural precision. There was the fisherman in Belarus who died when a beaver bit through his femoral artery.

COWS

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 cows survived.

DOLPHINS

It sounds outrageous, but it’s true. 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.

PRAIRIE DOGS

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. They are plant-eaters, so once they’ve bitten the squirrels to death, they just drop the carcasses and stroll away.

SLOW LORISES

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.

SWANS

A swan that killed 15 other swans and injured dozens more was named Hannibal. This swan 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.

HIPPOPOTAMUSES

Each year, the humble hippopotamus kills more people than lions, tigers, or bears. 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.