The trope namer itself. With those teeth, they can inflict quite a bit of damage, and rabbits are hardly docile creatures. Male rabbits will rape so that they can breed like rabbits, and castrate rival males to ensure their own breeding rights. Yeah. Rabbits castrate each other with no anaesthesia. They also headbutt, and their kicks pack quite a bit of power for their size, to the point that they can break their own spine if they kick hard enough. Some rabbits are known to attack snakes. One gained fame for trying to board Jimmy Carter's fishing boat in 1979. It was even nicknamed "Killer Rabbit" by the media.
There was also a story circulating in Russia about a naturalist who observed a rabbit attacked by an eagle turn on his back and eviscerate the eagle with the claws on its hind legs. The eagle apparently died a horrible death.
this youtube video shows a mother rabbit dealing a world of pain to the large snake trying to eat her babies. The serpent can't get away fast enough.
In general, an animal with large, forward-facing eyes will look cute to humans. An animal with this feature is almost always a vicious predator. If not, they are a primate or a sloth, which are also listed here.
The Secretary Bird of Africa is another example. They look very cute and seem relatively harmless at first, but they are actually ferocious predators. They very closely resemble the small predatory dinosaurs known as raptors that lived millions of years ago, such as Velociraptor and Troodon. They are endowed with a sharp, curved beak and razor-sharp claws on their feet. Their kicks are very powerful, and they regularly prey on snakes. They snap the snake's spinal cord with their kicks, and then proceed to tear up its body with their claws and beak and eat it. They've been known to take on Black Mambas and win. They can be very aggressive towards humans sometimes, and they can allegedly shatter a human hand with a kick. In other words, if you're looking for a living, real-life Jurassic Park, look no further than this.
The prehistoric Bullockornis resembles a human-sized duck. With a viciously sharp beak the demon duck of doom makes Velociraptor look like an adorable bunny in comparison. Ironically, Bullockornis and other dromornithids are now considered to be herbivores. But given what its modern herbivore relatives like the other infamous aussie bird, the cassowary, can and will do, this isn't much reassurance.
Speaking of which, Velociraptoritself is an example of this trope. Even when it doesn't look like the one in Jurassic Park, a coyote-sized, feathery chicken-like dinosaur is perfectly capable of taking on a full-grown Protoceratops ten times its size, while alone. Tiny, cute, but it can kill you in an instant.
Domesticated dogs and cats still have hunter's instincts, and will often attack small animals they come across even if they're not hungry. Cats in particular, due to their mobility and stealthiness, are well equipped to hunt down various small animals such as birds and rodents that might be lurking in your back yard. Because they don't need the food, cats will often just play with their catches rather than eat them. For an added bonus, cats have a lot of bacteria in their mouths, which can make their bites surprisingly nasty - second only to that of a human being, in terms of infectiousness. (If you are bit by a cat, go get medical treatment!!) Cats were largely domesticated because their ancestors' presence was tolerated due to them being very good at pest control, which became extremely important around 10,000 years ago when humans decided to settle down and take up agriculture.
Dogs are also famous for attacking other people and even large predators that decide to threaten their owner. This is expected from large breeds like rottweilers, but even the smallest of dogs are known to turn absolutely fierce when their master is in danger. Cats have also been known to do this, but much less often.
Siberian Huskies. The Chukchi tribes that originally bred them would turn the dogs loose in the summer, forcing them to fend for themselves. This led them to having a very strong prey drive. Any Husky owner will tell you just how quickly they will chase small animals such as birds, rabbits, squirrels, cats and even small dogs if they spot one.
Koalas. It's not hard to piss them off, especially if you interrupt one of their 19 hours of sleep, and they have huge teeth and claws that can do some real damage when you rile them up. Please stay away from them. Fun fact: they are always POed at you because they're coming down from a high. Eucalyptus leaves actually contain a mild toxin, to which they have built up a resistance that instead makes them stoned. Hence the sleeping 19 hours a day.
Wombats can do a fair amount of damage too - one naturalist ended up with a 2cm deep bite in his leg. Through a gumboot, trousers, and thick socks. And if they get some speed up (40km/hr at maximum, despite being generally slow) they can knock grown men over. This being Australia, their main defence against predators is to hide in a hole and use their cartilage-heavy, armour-plated arse to keep themselves from serious harm note The source of the "drop-=bear" urban myth made famous by Terry Pratchett in the The Last Continent — and their modified pelvic bone that forms the aforementioned armor-plating is sturdy enough to crush a dingo's skull, if one manages to get its head into the hole before it's completely blocked off. Australia is potholed to Death World for a reason.
There's been instances of cars hitting wombats and flipping over. The wombat was fine. The car? Not so much.
They also had some impressive extinct relatives, such as the hippopotamus-sized Diprotodon (which may have inspired the mythical Bunyip) and there's even evidence that Thylacoleo (Marsupial Lions) were also wombat relatives.
The platypus looks like an adorable beaver-duck, but the poisonous stinger of the males contains one of the nastier venoms known to man. It causes immediate hyperalgesia in humans, which is acute hypersensitivity to pain that can't even be dulled by painkillers without resorting possibly lethal dosages and can last weeks to months. Yikes! In other words: it won't kill you, but it will make you wish that it did.
Also not well known is the fact that kangaroos, are, in fact, ripped as hell◊ and not at all afraid to use it if you piss them off.
Due to causing vehicular accidents, the deadliest animal in the USA is the deer. Moose are even worse. Think you're safe in your two-ton cage of speeding metal? Think again! Hitting a deer or moose can easily cause a fatal accident. Moose legs are also uniquely suited to slide up a car hood and through the windshield in a collision.
Not to mention their antlers, sharp hooves, and teeth. An annoyed horse will just bite your hand really hard then let go, to tell you stay away. A deer that thinks you're trying to kill it, however, bites your hand then tries to rip your hand off.
Red deer regularly devour birds, rodents and even smaller deer.
Not to mention the fact that apparently Moose eyes don't reflect light so it's very hard to notice them in the dark. They are also quite aggressive.
While emus don't fall under the generally accepted category of "cute", they are essentially human sized birds with fluffy feathers and big, expressive eyes. They can also kick you to death in a matter of seconds. Most of those tall, long-legged, flightless birds aren't that harmless. Ostriches are reputed to be able to disembowel a lion.
The emu's relative the Cassowary is essentially a Velociraptor with a beak. Also, Eye Scream, they are attracted to shiny objects, like human eyes. Which are at beak level. The cassowary, a rather silly-looking◊ flightless bird best known for having an oddly-shaped head, also sports a set of claws that make it pretty much the closest modern-day equivalent of a velociraptor◊. If you manage to piss one off, it can and will eviscerate you, and there are numerous cases of death-by-cassowary on record. They have been known to eat metal.
In other words, these guys are the last of the Old-School Dinosaurs.
The blue-ringed octopus. Not exactly cute, but it definitely wouldn't look very threatening, despite being one of the most poisonous sea creatures known to man. As comedian Billy Connolly says "It wouldn't fit in the palm of your hand, but if this thing's in a bad mood you don't make it to the *** phone!"
The striped pajama squid. It is exactly as adorable as you'd expect from the name, but it's also the second-most venomous cephalopod after the blue-ringed octopus.
Octopi are mostly known as tiny and occasionally even cute little animals that have amazing abilities of fitting into the smallest cracks and change their skin to match any surface. So when the staff of a marine aquarium decided to move their North Pacific Giant Octopus into a tank with their sharks, they didn't expect it to have any trouble staying safe. And then each night more and more of the sharks were disappearing or found dead.
Betta fish are small and very colorful, known to be ideal for beginner fish owners due to their hardy nature or because they are just that beautiful◊. They are also infamous for their extremely aggressive behavior: A Betta will rip another fish to shreds if it has the motive and the opportunity to do so, as many unfortunate people who made the mistake to put two or more Betta together on the same tank or bowl can testify. They'll even attack mirrors that are put in front of them, thinking it's another fish. There's a reason they also known by other name: Siamese fighting fish.
Mustelids (ferrets, minks, weasels, martens, sables, polecats, badgers and wolverines) are unbelievably strong for their size. They are not afraid to fight back fiercely when threatened by greater predators, despite their cute, fluffy appearance. There's a reason why badger is a verb and Wolverine is a superhero. The entire group has this trait making them some of the deadliest predators in their habitat.
It should be noted, though, that the European Badger is a shy social animal (they live in small family groups) that prefers to avoid confrontation and will only fight back when it is unable to escape. The badger's dubious reputation as a feriocious animal actually comes from the old "sport" of "Badger Baiting". Which, sadly, pretty much consisted of trapping a badger and forcing it to fight to the death against hunting dogs.
The badger's reputation of reluctant ferocity and toughness is well deserved. Their skulls and hides are incredibly thick, and layered with tough muscle that makes them highly resistant to 'cudgels, blades, and shot' according to monographs from periods when they were hunted. In addition, their burrowing claws are capable of doing massive damage. Oh, and that thick skull? Its built in such a way that once a badger locks into a bite it must be dislodged with crowbars. Post-mortem. Beware the Nice Ones indeed.
Wolverines, in particular, are dangerous little bastards. Grizzly bears are known to give these things a wide berth. Grizzly bears. Wolverines can also climb a 13000 foot peak in just one and a half hours. In the middle of January in fifteen feet of snow.
Even the weaker ones, such as the Least Weasel and the Stoat, despite looking shy and fragile, are actually capable of killing prey five times their size. Even the much stronger Wildcat and the aggressive sewer rat will usually avoid confronting them. Indeed, Least Weasels are known to go down into rat nests and kill everything there.
There's also the fisher, one of the few animals which will attack and eat porcupines.
And then there's the Honey Badger, their more irritable African cousin. The honey badger is kinda cute, but it has thick, tough skin that acts as some sort of body armor, giving it some protection against the claws of large animals such as lions. Its skin is too thick for the fangs of venomous snakes to penetrate, so it can eat those. It sometimes attacks (small) crocodiles. There's a reason "Honey badger don't care" became a meme.
These things have been known to chase off, if not kill, full grown lions. How? it uses its small size and speed to run right under the lion, and try to rip its balls off. Also, these little guys will growl, hiss and charge at their attackers to frighten them away. And, if that doesn't work? They produce a rather foul smell from their behinds, much like skunks. And, yes, it's quite effective in driving predators away. Oh, and the name? Comes from the fact that they really like honey. How does it get said honey? By shoving its face into an occupied bee hive and chowing down while ignoring the bees' protests, and keep in mind, these are African honey bees, aka the granddaddies of Killer Bees.
They're also very smart, being one of the few animals that have been documented using tools; a Honey Badger was filmed using a log to help it reach a small bird that was tangled in some vines.
Young cheetahs, when rolled up for a rest, look just like a honey badger when rolled up for a rest. This is a mimicry-type security measure - for the cheetah...
The Giant Panda. Another contender for "cutest bear" (it is a card-carrying member of the bear family, as shown by molecular genetics), a truly ridiculous amount of time, effort, and money has gone into saving these fat and lazy animals. Some people might think pandas are vegetarians because they only eat bamboo. They only eat bamboo because it's one of the only things that can't outrun them, being plants. Give an adult 200 pound panda a chance, and it will kill and eat small animals, possibly including children. Fun fact: Pandas actually have a carnivore digestive system. Its round face is the result of powerful jaw muscles, which attach from the top of the head to the jaw.
A National Geographic article once told about a panda named Zhen Zhen who terrorized a camp, demolishing tents and attacking people.
A article in the London newspaper Metro involved a viper that was rescued from a house in China. The rescuers tried to feed it a live mouse and the mouse killed it after a half-hour struggle. They could only theorise it had run out of venom during the capture.
Raccoons, anyone? They look like fuzzy little puppy-cat things with domino masks, but their teeth and claws can kill pets and send people to the emergency room. To top it off, they're the biggest carrier of rabies in North America (though domestic dogs are the biggest rabies vector in general). That's not mentioning the fact that they also tend to have really, really nasty tempers and utterly zero fear of humans.
There's at least one known instance of a Dachshund killing a very, very aggressive German Shepherd by luring it under a parked car and, using its smaller size to maneuver, tearing its throat out. Helps that their teeth are not a small dog's teeth.
Popular perception of dolphins pictures them as happy and cheerful, but their bodies have more than enough strength to severely hurt and even kill small sharks and humans, two species of badass apex predators. Dolphins also tend to torture their prey before killing them. And then there are the bottlenose dolphins, which could very well be described as Flipper's evil twin. Also, dolphins will try to fuck Anything That Moves, and will rape you if they get half a chance. Think twice about their smile.
Orcas or killer whales. They're beautiful and majestic and adorable if you see videos of them interacting with humans. But these guys are the top predator in every ocean, even the Arctic. They use their brains and massive size to take down prey, which is basically anything in the ocean. They even eat sharks, rays, dolphins and whales. Not just smaller ones like narwhals but also they go after large ones like humpback whales.
There are some tree frogs, small and rather beautiful. And whether they are alive or dead, merely touching them with one's bare skin is a bad idea. With a tip of blowgun dart, on the other hand.... Fortunately, the ones in captivity are not fed the ants that cause them to produce said toxins.
Shrews are fuzzy and tiny, which is a recipe for textbook cuteness. Gram for gram, they're also the most voraciously-bloodthirsty predators on the planet, killing prey many times their own size and eating anything that moves, and consuming triple their body weight daily. There's a reason why they got the number one spot for "Most Extreme Predator" in The Most Extreme. Some of them have venomous saliva as well, so be glad these things are so little.
Chimpanzees. Most funny and human among the whole lot of funny monkeys, right? In reality they are insanely strong (a 70 kg male can lift up to 300 kg; less surprising when you take a look at those muscles◊) and very dangerous when pissed off. Some have killed adult people and even kidnapped and eaten human babies. Intra-species murder, wars between bands, and even cannibalism aren't unknown in them either. And yet people still think worse of the comparatively harmless gorilla...
Except for humans, though, apes exceptionally strong arms are essentially useless except for pulling. Gorillas and chimps don't have the right musculature and could likely be outpunched by a young human child. Doesn't stop them from tearing off your arms or ripping your face to shreds.
Pigs are generally thought of as ugly, fat, listless, and generally harmless creatures... unless you are a pig farmer. Editor has been told that a farmer being trampled (and subsequently eaten) is not unheard-of.
Modern swine are much more docile than their Iron Age ancestors, which were more like barely tamed boar. In Ancient Rome, pig farming was infamous for the extreme danger involved. Think about that the next time you read The Odyssey, which was set in Ancient Greece (and therefore even older)—Eumaeus had to be a Badass to do his job, so he would have been no slouch in the climactic battle!note And the Biblical story of the Prodigal Son, who became penniless and friendless and who had to take on a job nobody else wanted. Not because of the unclean status of pigs in a Jewish land. Or the associations. Who do you think would want to herd pigs in Jewish Palestine apart from the hated Roman occupier? So. A collaborator with the Romans who makes himself ritually unclean. AND into the bargain is forced into an unsanely dangerous job. Jesus knew what he was doing when he chose this career for his Prodigal...
Perhaps best illustrated by the attitude of the veterinary profession. Cows that can kick and gore and break bones? Stocks, tranquilizer, good to go. Horses that can do the same? Experienced equestrian, tranquilizer, no problem. Sheep? Pshh, sit 'em on their rumps, end of problem. Pigs? WE NEED LOTS OF DRUGS AND HALF A DOZEN NURSES AND A FARMER WITH A METAL CATCHPOLE AND A REALLY STURDY METAL PEN AND EXCELLENT EARPLUGS AND IF I DON'T MAKE IT OUT HERE'S MY WILL.
While Bulls are already perceived for being badasses, Cows aren't that much far behind in that regard.
Squirrels are cute, nervous, and fuzzy. Harmless, right? Or are they arboreal piranhas?
The Cone Snail. Many people pick them up because they're pretty... and get a deadly neurotoxic harpoon stuck right into them! Due to the speed at which the snail fires the harpoon, they are actually the fastest snails on earth. The toxin is so deadly that the cone snail is nicknamed the "cigarette snail" - you have just enough time to smoke a cigarette before you die. The only way to survive is to be put on life support until the poison wears off.
From the right perspective, jellyfish can look like gracefully-flowing gossamer, living chandeliers. But one touch and you'll know what days of agony is like if you're lucky; if not, and it's one of the nastier species, you'll learn what a few minutes of agony and the afterlife are like.
Man-o-wars. Look like jellyfish but are really a colony of different organisms where one is a purple floating sac and the rest are tentacles that make digestion and attack. From outside the water, it looks beautiful◊. Under the water, they are goddamn painful and, in some cases, can kill a person.
Ladybugs (or ladybirds, if you prefer). Sure, they look cuddly (even for a bug) and are often seen as innocent, but for aphids, they're your worst nightmare. Ladybugs ravenously devour them to the delight of gardeners everywhere as aphids are serious pests.
Chow Chows basically just look like big balls of fluff, but they have a reputation for being aggressive - to the point that the words "chow" or "chow mix" are basically code for "be on your guard" in your average veterinary clinic.
There's a reason Chow Chows have been described as the dog that looks like a lion and thinks like a cat.
Pit Bulls and Rottweilers go for your limbs, to hurt you. Chows go for your throat to go for the kill.
They were originally bred in Northern Mongolia and Siberia to hunt, herd, pull sleds, and guard royalty.
Sloths. They're big, sleepy, slow-moving critters... living in jungles. Y'know, where EVERYTHING tries to eat you. Think about that for a second.
The sloth's ancestors were roughly the size of elephants and could basically do whatever the fuck they wanted without having to fear predators.
Anteaters don't even have teeth, but they've got claws to compensate. And if you ever see one of these walking on their hind legs, run. It wants to hug you, and if you put two and two together, you'll realize it isn't a friendly hug (the biggest anteaters kill predators that way).
Poison ivy is gorgeous. It has glossy green leaves which are red when new, and a stunning purple fall color. It also has attractive white berries that birds love. It causes ferocious allergic reactions. Once it's on the skin, most efforts to alleviate the pain will only serve to spread the irritant oils. It grows quickly, and with its berries so appealing to birds, spreads rapidly. If burned, its irritants will be carried in the smoke, and will tear up the lungs of anyone who inhales that smoke. It also seems to be responding to elevating atmospheric carbon dioxide levels by increasing the potency of its irritants.
On the other hand, half of the population likely to be exposed to it is just flat out immune. Amusingly, when the MythBusters attempted to test poison oak home remedies, none of them proved to be susceptible (until they got to John the researcher, sixth on the depth chart), though admittedly it could conceivably have been a false negative, as it's possible they had never been exposed to it beforenote Kari was banned from the test due to prior severe reaction; like all allergic responses, the initial exposure does not produce an effect but every exposure thereafter usually does.note On the other hand, Grant said on-air that he'd had reactions before, and Tory's choice of words after his test ("...but apparently, I don't get it anymore") implies he had as well; neither got a rash during the course of the test.
Skunks. They're cute, gentle, and will totally ruin your day if you even make a wrong move around them.
They also have little fear of humans. (Only one animal regularly preys on them — the great horned owl, who has essentially no sense of smell.) So they are more likely than most wild creatures to come close enough for Regrettable Misunderstandings to happen.
A lot of plants look totally harmless but are actually quite dangerous. For instance, Oleander has beautiful flowers but it is very toxic.
Special mention should go to teddy bear cholla, a cactus which, despite the name, is phenomenally un-cuddly. The name comes from the fact that it looks almost fuzzy, which, combined with the strange shapes it tends to grow in, makes it look kind of comical. The "fuzz," however, is actually thousands upon thousands of hair-thin, transparent, barbed thorns that come out at the slightest touch and lodge in your skin. Guess bears are REALLY bad news.
Honourable mention must go to the giant stinging tree. It does the same while looking EVEN more unassuming. One slight breeze and everything in a 3 block radius suddenly feels like it's ON FIRE!
Grasshopper mice are tiny, fuzzy, and cute. They also howl like wolves and supplement their usual diet of insects with the occasional snake.
Inverted with the Hickory Horned Devil caterpillar, the largest caterpillar in North America and larval form of the regal or royal walnut moth. It's five inches long, covered in menacing-looking spines from head to end, and yet it's completely and totally harmless.
But played straight with the puss caterpillar. Awww, isn't it cute and furry, like a little tribble? Until you touch it, that is, at which point you're in for a world of pain.
Show breeds of Cocker Spaniel are subject to a phenomenon known as "Cocker Spaniel Rage," in which they flip out and attack for no apparent reason. That's right, Lady may one day try to kill you out of the blue.
Chihuahuas have a lot of bad temper and use to attack in packs, like a horde of angry rats. Some people have been savagely mauled by packs of the tiny bastards, including a police officer in a 2005 incident. Makes one wonder why Paris Hilton is fond of them...
Swans: graceful, regal, a symbol of love ... and equipped with wings strong enough to break your arm at a blow if you come near their eggs.
Velvet worms. Probably another Ugly Cute example, but they're soft and squishy things that crawl slowly over the forest floor on stubby legs. And are predators. That can kill prey the size of tarantulas. (They do it by spraying a sticky slime that quickly hardens into a net to trap their prey. And then they close in and eat the helpless prey alive.)
Moles. That's right, the blinky/blind, fuzzy, shy-but-friendly little guys. These guys may be cute, but they are vicious little blighters: they are predators capable of hunting underground, and burrowing their own tunnels to do so, and are incredibly territorial. Oh, and cannibalistic- put two moles together for any length of time and you end up with one fat mole.
Do not go to pet a dingo. They might look like Labrador Retrievers, but they're very much not domesticated, so for the love of God and for the love of your future children, do NOT pet it!
Tasmanian devils. They're actually much cuter in real life◊ than the cartoon character, but they are obligate carnivores with the strongest bite of any mammal, able to take down prey as large as a kangaroo. Not to mention they're extremely temperamental and loud.
Inverted with the Horseshoe Crab. They have dangerous-looking spikes on their tails and bodies and tails that look like stingray tails, but they're harmless and can't really hurt you.
The mantis shrimp is a small, often colorful little critter that lives in coral dens and mostly keeps to itself. To eat its dinner of molluscs and crustaceans though, the mantis shrimp doesn't bother with prying them open: it BLASTS them open with its clublike arms, which strike with the acceleration of a .22 BULLET. The force generated per area is so powerful that the mantis shrimp can COMPLETELY MISS its target and STILL do damage by force alone. Captive mantis shrimp have been known to crack or shatter aquarium glass with a single blow. They have another name: thumbsplitters.
An awful lot of tropical reef fishes and invertebrates, including the drop-dead gorgeous ones popular for saltwater aquaria, are deadly poisonous, and even the nonvenomous species may sport razor-sharp spines for protection. Heck, even the coral can cut you to ribbons if the current makes you bump into it.
Shrikes are small, cute songbirds that kill mice and lizards by impaling them on thorns, then use the neatly strung-up corpses as a larder.
Most large frogs, but special mention goes to the American Bullfrog. Funny-looking, not particularly fast, no obviously deadly attributes. But it will eat anything. ANYTHING. In Southwestern areas, it will jump out of the water at night to hunt lizards, rodents, scorpions and tarantulas. If a scorpion is too big to swallow, it will chomp down on it, then fold it in half with its forelegs and shove it down its gullet.
Pretty much anything that isn't newborn and isn't obviously dangerous has potential to be this. Natural Selection is the biological equivalent of Training from Hell on this planet. Even the vegetarians can rip the unwary a new one. Hell, even the vegetables can!
Inverted with Crane flies. They may look like gigantic mosquitoes, but the worst a crane fly can do to someone is when they're larvae. Then they can do some damage to your lawn.
Often rats in many cases. Not only do rats tend to look a lot more aggressive and disease-ridden than their other rodent cousins such as the mouse, they can be more aggressive, and are just as susceptible to carrying and spreading contagious diseases. And can be even worse pests than mice in many cases. Inverted with domesticated rats, which are sweet-tempered and friendly despite their species' bad reputation.
Patterdale terriers and Jagd terriers (German hunting terrier) are still used for boar hunting and vermin hunting. Unlike many dogs, they still have the original strength and ferocity since they did not become just show dogs like dachshunds.
The more brightly-colored and striking an amphibian is, the more poisonous its skin is likely to be. This also applies to insects, fish and reptiles. Its theorized that these bright, striking colors act as a warning for predators that says "do not eat me, I'm poisonous". Some species, such as the king snake, go so far as to imitate this look despite not being poisonous themselves.
The Hippopotamus species have a popular reputation of being fat and contented creatures. However, they are highly territorial and kill more people in Africa than lions. Including killing lions. And despite their huge size they can outrun humans. To put this in perspective, Steve Irwin, the Crocodile Hunter, described a short boat-ride over hippo-occupied water as the scariest moment of his life. Steve Irwin.
Because they are so scary, they deserve some more information. First off, they are the second largest land animal on the planet (only beaten by the elephant and tied with the rhinoceros).
Unlike most animals dominance fights, which are largely ceremonial and end with minor injuries, male hippos fight to the death for territory, which comes with food and mates.
Pablo Escobar, kingpin of the largest drug gang the world has ever seen had a pet hippo. Which he fed people.
And without hippos, the rivers where they live would die. Large animals produce large amounts of fertilizer. Hippos produce over 120 lbs a day. They also distribute it by means of twirling their tails at high speed. A case of shit literally hitting the fan.
When people think of seals and other pinipeds, they tend to visualize the cute, adorable circus or aquarium animals that have been trained to honk horns or bounding happily on the beach. People even consider them to be the sea's equivalent of a dog. However, sea lions are immensely aggressive and have been known to seriously maul humans, in addition to routinely killing each other. Antarctic expeditions have been attacked and at least three people have been killed by leopard seals in the past. And if they climb up onto docks, or even into cities? Don't try to approach them. It will end in a visit to the hospital, possibly without one hand. Oh, and those goofy-looking elephant seals? You know, the big ones with the silly, drooping noses? Here's a video of one having a disagreement with a parking lot... looking strangely adorable while doing so. Something to keep in mind is that the closest living relative of the piniped family is the bear family.
The pelican, a waddly goofy looking bird with a weird neck and beak pouch, the larger ones can eat a pigeon in one swallow.
A Belorussian man was attacked and killed by a Beaver, similar, non fatal attacks have occured in other places.
The US Army survival manual specifically suggests not attempting to trap a beaver unless you can kill it from a distance because of the grievous wounds it can inflict with it's teeth.
If you think snakes are cute at all, baby venomous snakes fall under this, especially baby cobras. They have huge eyes and a cute stripey pattern. They're no less venomous than adult snakes, and sometimes even inject more venom than an adult snake would, because they haven't learned how to use it yet.
One of the biggest warnings that anyone will receive when doing amateur diving on or near tropical coral reefs is "don't touch the fire coral". Fire coral isn't a true species of coral, its actually more closely related to jellyfish and anemones. This is what one variety looks like◊. Like jellyfish, they have nematocysts, which shoot out and deliver venom into anything that touches the fire coral. If you so much as brush one with your bare skin, you will be in some of the worst pain of your life.
Subversion: Siberian musk deer. Seen from afar, it's an adorable bambi. Seen from up close, it's an adorable bambi with creepy vampire fangs. Despite the look, it's not a particularly dangerous animal.
Humans. We are much cuter (from a human point of view, at least) and weaker than many animals, and yet we can eat things that are not supposed to be eaten by anything (spicy foods are supposed to be repulsive to mammals, potatoes, almonds and many other foods are poisonous and yet we found a way to make them edible, and blowfish is supposed to be an insta-kill), and have eaten to extinction many animals bigger than us that were unlucky enough to first meet humans after we had perfected our hunting techniques (big animals that are still around were either lucky enough to see us perfecting our techniques and learned to fear us, lucky enough to live near better preys and have time to learn to fear us while we exterminated something else, or lucky enough to be domesticated). Everything fearsome on this world, including bears, sharks, tigers, crocodile, and pretty much anything on this list, fear starving humans, because, with modern hunting techniques and weapons, the only reason they're still alive is that we learned restraint.
And humans also deserve bonus points for also being dangerous to the itty-bitty microrganisms/zombie-like almost-organisms (viruses) of the world too. We've managed to destroy wild smallpox virus and now it's all but extinct (with a couple of reservoirs in some hopefully very well-guarded labs floating about.) And now polio is hopefully next. Buahaha!
Armadillos; generally they'll flee from any humans by burrowing, and prefer to lock themselves in place; if you try to root them from a surface it will take effort to dig through, but most Armadillos carry leprosy, which they're immune to. A single swipe on raw skin could very easily give you one of the most feared contagious diseases in world history.
The porcupine puffer is a friendly-looking curious fish that also happens to be a vicious predator. Yes, you read that right. Porcupine puffers (like all puffer fish) have teeth that are formed into a beak-like shape that's razor sharp. Likewise, they have powerful jaws that allow them to crack open the shells of creatures like clams and snails. Here's one eating a hermit crab.
They're not short on defenses either. Like all puffers, they can inflate their bodies to intimidate predators, and they have the added bonus of being covered in sharp pointy spines (hence how they got their name). And, if those defenses don't work...Well, did we mention that their bodies contain a poison that's 1200 times deadlier than cyanide?
Puffer Fish are also notoriously territorial, even the little ones, to the point where they'll attack any other fish in the same tank. Now, that may not seem like much, until you realize that they are known to attack fish much larger than themselves. There are many accounts of fish owners putting a larger fish in the same tank as the puffers only to check on the tank the next day and find the larger fish is dead. Turns out the larger fish died a slow agonizing death because the puffers would repeatedly attack and tear it to shreds.
This cat apparently went absolutely ballistic, started trying to attack everyone in the house, and was only eventually stopped when the police arrived and trapped it.
As seen on My Cat From Hell, he was suffering from feline hyperesthesia syndrome, which normally results in the cat attacking itself in confusion. It can be worsened by stress, and treated with anti-seizure medications.
Porcupines also deserve a mention. Most people assume that porcupines are just a bunch of pudgy, clumsy looking rodents who only managed to avoid being a predator's meal by virtue of being too spiky to eat. However, old-World porcupines will take the offensive by turning around and running towards persistent attackers with their spiny backsides, hoping to stab them. The Indian Crested Porcupine does this so effectively that brushes with predators like leopards and tigers often result in death or severe injury. The lucky ones that manage to survive often are forced to become man-eaters because of their injuries. It's for this reason that porcupines have very few predators.
Australian magpies may seem like harmless songbirds, but they do have a reputation for attacking people who come near their nests.
Silly as it may sound, there are such things as guard llamas. Single llamas living with other livestock (including cattle and poultry) often become very protective of their charges. Unlike most domestic herbivores, llamas will go on the offensive and attack any predators that threaten the herd. As a result dogs and coyotes have been injured and even killed by llamas. A study done on the effectiveness of guard llamas and sheep found that average sheep losses dropped from 26 sheep per year to 8 sheep per year when the camelids were put into place. To the sheep ranchers, everything really is better with llamas.
Somewhat inverted with opossums. They look like giant rats and have 50 teeth with big, sharp canines (especially the males), which they show off as defense with loud hissing, which makes them unfairly associated with aggression and rabies. But it's a bluff; they're usually quite docile, and much less likely than other wild mammals to carry rabies, due to their cooler body temperature and tough immune system.
Many docile and adorable house pets that look totally cute and non-dangerous will go into a Killer Rabbit mode when they feel seriously threatened. A nice, cute hamster or an extremely friendly and docile pet rat can inflict some serious damage to its owner or anyone who gets close to it once it feels it's a Last Stand situation ("a cornered rat bites the cat").
Keas. They're just as cute as any other parrot, but they can also badly damage or destroy cars, mainly by tearing at the metal or windshield wipers with their powerful bills. They also eat meat.
Jimmy the Groundhog, awakened from a sound sleep to appear on television in a local Groundhog Day prognostication ceremony, expressed his disapproval of being dragged from his nice comfy nest by biting the mayor on the ear. Given the strength and sharpness of rodents' incisors, the man was lucky not to lose the ear.
Pygmy Falcons are smaller than pigeons, and are much cuter than what most people would expect from a bird of prey. Despite this, it has all the hunting skills and instincts of its more badass-looking relatives, preying on reptiles, insects and small mammals in Africa.
Hooded pitohuis are brightly colored, seemingly normal-looking songbirds. They're also one of the very few poisonous birds in the world, with a strong toxin in their feathers and skin. The toxin makes anyone who touches it feel like their hands are on fire.
Foxes. They're cute, admirable, beautiful creatures. Also shy, retiring, and liable to do a fade into the underbrush long before a big blundering human catches sight of them. Except sometimes they turn quite friendly, even tame, and approach humans wanting to play and be petted. This is when they are at their most deadly dangerous. These are the symptoms of rabies in foxes. Even touching the fox will transfer the rabies virus to, say, your hand, and if you then rub your eyes, you won't know you're infected until it's Too Late. Experienced outdoorsmen will tell you, in full earnest: If you meet a friendly fox, kill it without hesitation.
The slow loris, a tiny nocturnal primate with cartoonishly huge eyes swallowing its head, is one of the few venomous mammals. It produces a toxin in its elbow that is activated with its saliva and can give a toxic bite that can trigger a fatal anaphylactic shock.