With fluffy faces, a timid demeanour and diminutive size, some animals look about as far from being dangerous as it is possible to imagine.

Some seem almost helpless in the face of predators. Others, encumbered with clumsy appendages, appear almost too ridiculous to be much of a threat.

Yet despite their cute, silly or feeble appearance, evolution has gifted a handful of animals with special abilities that make them a force to be reckoned with. These are nature's secret ninjas.

Norwegian lemmings

Barely 6in (155mm) long, covered in thick dark brown, white and orange fur, these little rodents have an almost chubby appearance. They spend their time burrowing through the thick snow in the Scandinavian Arctic during the winter, and scampering beneath low-lying shrubs on heathlands in the summer.

The creatures also have a reputation – which is completely made up – for committing mass suicide by throwing themselves off cliffs. But in reality, Norwegian lemmings have a ferocious survival instinct and an attitude to match.

Their strong incisors are a dangerous, sometimes even lethal weapon

Faced with a predator many times their size, they do not turn and flee. Instead, the rodents will face down their opponent for a fight while emitting loud screams, lunging forward and biting with their sharp teeth. There are videos online of Norwegian lemmings taking on cats, birds of prey and even large dogs like bullmastiffs.

"Such aggression can be effective against small predators, for instance long-tailed skuas, weasels and stoats," says biologist Malte Andersson at the University of Gothenburg in Sweden, who studies Norwegian lemmings.

For some reason, the colourful Norwegian lemming is more aggressive than other lemming species like the brown lemmings found in Alaska. A 2015 study by Andersson suggests the distinctive white cheeks and chin of the Norwegian lemming may be an adaptation to direct predators' attention towards their main defensive weapon: their teeth.

"Their strong incisors are a dangerous, sometimes even lethal weapon against small predators such as the weasel," says Andersson. He says he has even found himself on the receiving end of some lemming aggression during his research, with the rodents squaring up to him if he got too close.

Japanese land snails

With their soft, meaty bodies, snails make nutritious snacks for many small mammals and birds, but their hardened shells provide these molluscs with some protection. Most species withdraw inside their shells at the first sign of danger, taking refuge there until the threat has passed.

They bludgeon their attackers into submission

But two species of land snail from the Far East have a rather different attitude when it comes to dealing with predators.

Karaftohelix gainesi (sometimes known as Ezohelix gainesi) from Hokkaido, Japan and K. selskii from eastern Russia both use their muscled bodies to swing their shell like a club at approaching predators.

The two snails are commonly preyed upon by beetles, but rather than hiding inside their shells, they bludgeon their attackers into submission. The snails swing their shells almost 180 degrees in less than a second, knocking the beetles aside.

Biologist Yuta Morii of Hokkaido University in Sapporo, Japan, who described the snails' defence mechanism in 2016, says they have also evolved much wider shells compared to snails that simply curl up and hide. "A larger relative aperture might allow development of strong muscle to swing the shell around the soft body," he says.

Slow loris

Their huge round eyes, adorable faces and almost human-like paws have made slow lorises one of the internet's favourite animals. Being nocturnal, the little primates seem almost docile during the day: when they do move around, they do so slowly and deliberately. When threatened, they tend to freeze.

But slow lorises also have a lethal ace up their sleeve, almost literally.

In extreme cases, bite recipients may enter anaphylactic shock, sometimes resulting in death

When threatened, a loris will often raise its arms above its head. Far from being a sign of surrender, this is a defensive posture, bringing a gland around its elbow close to its mouth.

By combining the oil secreted from the gland with saliva, the loris creates a strong venom, which it then smears onto the top of its head, making it a toxic morsel for any predator.

The loris can also keep the venom inside its mouth, delivering it in a bite. The incisors at the front of the bottom jaw help to conduct the liquid upwards, ensuring it gets into any wound it can inflict.

According to Anne-Isola Nekaris of Oxford Brookes University, a bite from a slow loris is "intensely painful". "In extreme cases, bite recipients may enter anaphylactic shock, sometimes resulting in death," Nekaris says.

There are nine known species of slow loris living in the forests of South East Asia. The venom of the pygmy slow loris (Nycticebus pygmaeus) has been found to contain 220 compounds.

So, the next time you watch a video of a slow loris being "tickled" with its arms in the air, remember it is not enjoying the experience: it is waiting for a chance to strike.

Fulmar chicks

Unable to fly and stuck in their nests on often precipitous cliff faces, these football-sized balls of downy feathers ought to be easy pickings for predators; at least, for those that can reach them.

But fulmar chicks, like many other birds in the petrel family, have a rather disgusting way of fending off attackers: they vomit on them.

Fieldfares will mob predators and defecate on them, causing their feathers to become clogged with faeces

They make a concentrated oil in their stomachs, distilling it from the waxy residues left after they digest their food, before squirting it out through their mouths.

The pungent fluid has been found to contain oils from whale blubber. Not only is the smell of the vomit deeply unpleasant – it has a foul and musky odour that can persist for years if it gets onto clothing – it is also deadly.

The liquid clogs the feathers of predatory seabirds like gulls, stripping them of their waterproofing. Scientists report that seabirds hit with the vomit attack often try to wash it off their feathers in the sea, only to become waterlogged and so unable to take off again, eventually drowning.

Fulmar chicks have been reported killing other predators with their vomit attack, including owls, gulls, herons, crows and even sea eagles. Even innocent birds such as puffins are not exempt from the vomit attack and can be sprayed if they stray too close to a chick. There have also been reports of rabbits found dead covered in the oil.

Adult fulmars can also spray oil on their foes. However, they use it less readily, often issuing warnings by shaking their head from side to side and firing warning shots.

Fulmars themselves do not seem to be affected by the oil's effects and can wash it off quite easily.

Other birds have an alternative, but equally disgusting, approach to self-defence. Fieldfares will mob predators and defecate on them, causing their feathers to become clogged with faeces to the point where they become grounded.

Emei moustache toad

Moustaches are fun, right? Not when the male who is wearing it is a three-inch-long amphibian from slow-flowing streams in southern China.

Each spring, male Emei moustache toads (Leptobrachium boringii) sprout between 10 and 16 spines on their upper lip. Made largely of keratin, the same protein that makes up our nails, the spikes can grow up to 5mm in length.

When threatened they break their own bones and shove them through their skin

At the same time, the males develop thicker skin and their forearms bulk out. Then they wrestle, attempting to stab each other with their outrageous facial decorations.

"The spines are a bit like a sharpened pencil," says Cameron Hudson, an ecologist at the University of Sydney who has studied the toads. "They are sharp, but you need to put some force behind it to break the skin. The toads scratch your hands while you're holding them, but they aren't sharp enough to cut a human. Toads, on the other hand, occasionally get bruises or puncture wounds on their underbellies and arms from combat."

As usual, the reason for all the aggression and violence is that the male toads are competing for females. However, the toads lose their jagged moustache when the two-month-long breeding season finishes and their hormones settle down.

Their nuptial spines are nothing compared to two other amphibians: the hairy frog and the Spanish ribbed newt. When threatened they break their own bones and shove them through their skin. For the frog, this creates claws like those of the superhero Wolverine, with which it can fend off assailants. Meanwhile, the newt pushes its ribs out of its body to give any predators a nasty mouthful.

Giant pandas

Pandas are the pinups of wildlife conservation and it is easy to see why: they have large round faces, big dark patches that make their eyes look bigger, and a childlike curiosity. Their seemingly lazy attitude to eating – sitting on their bottoms with their legs sticking out while chewing fistfuls of bamboo – only makes them seem more endearing.

Yet, while they might seem cuddly and even charming at times, giant pandas are still bears and, much like Jack Black's Kung Fu Panda, are not to be underestimated.

The black-and-white face patches we find so appealing may in fact be a signal of their ferocity

They have evolved extra muscles around their jaws to help them crush the tough bamboo they live on. That means pandas have one of the most powerful bites of all mammals in the Carnivora group.

Their paws are also tipped with six large claws – yes, pandas have six fingers – which are dexterous but can also deliver a formidable swipe. In the wild, they are partial to a bit of meat to supplement their otherwise vegetarian diet, often killing and eating small mammals like pika.

"Old-time hunters would bait bears by placing out a leg bone from livestock, and the pandas would crush the bones, not just nibble them," says ecologist Bill McShea at the Smithsonian Conservation Biology Institute, who studies pandas. "There are multiple reports of giant pandas breaking into livestock pens and eating goats and sheep."

Pandas do not seem to be overly aggressive towards humans, but there are reports of mother pandas injuring workers at nature reserves in China. In one attack that took place in 2016, a worker dressed in a panda suit – as part of a training programme to prepare the panda for reintroduction into the wild – had part of his hand bitten off and bones in both hands broken.

However, pandas reserve most of their aggression for each other. "During the mating season, males will have significant bite wounds on their shoulders and head from other males," says McShea. "The recent reintroduction of giant pandas into the wild in China resulted in the young panda being killed by other – probably adult male – pandas."

What's more, a study published in February 2017 suggested that the black-and-white face patches we find so appealing may in fact be a signal of their ferocity.

Secretary bird

With its stilt-like legs and long eyelashes, not to mention the ridiculous crest of feathers around its head, it is hard to take the secretary bird seriously. But this lanky bird of prey, found on the open grasslands and savannah of sub-Saharan Africa, has a kick to rival Bruce Lee.

According to a 2016 study, a single blow from one of these birds can deliver a force equivalent to five times its own body weight in just 15 milliseconds – a tenth of the time it takes us to blink.

While the birds themselves weigh between 3.5 and 4.2kg (7.7 and 9.3lb), their kick is enough to kill snakes, lizards or small mammals with a swift succession of kicks and stamps.

"The consequences of a missed strike when hunting venomous snakes can be deadly, so the kicking strikes of secretary birds require fast yet accurate control," says Steve Portugal, an animal physiologist at Royal Holloway University of London, who has studied the birds. "I would certainly not want to be on the receiving end of a kick from a secretary bird."

Cone snails

Their intricately-coloured shells are highly prized by collectors and even worn as jewellery in some parts of the world. But hidden inside these attractive shells are one of the most dangerous animals on Earth.

There are some 800 different species of cone snail. They are found mostly in tropical waters of the Pacific Ocean, but also off the coast of South Africa and even in the Mediterranean.

Only about 30 recorded deaths have been attributed to the molluscs

Although slow-moving, they are ravenous carnivores that prey upon small fish, shellfish and other marine snails, with the help of a harpoon they shoot out from the end of its proboscis. This hollow dart delivers powerful neurotoxins that can paralyse its prey within seconds.

The venom can also be deadly to humans, and the harpoon of larger snails has even been known to penetrate wetsuits. While some species deliver a sting no more painful than that of a hornet, others, such as the geographic cone snail, the tulip cone snail and the marbled cone snail, can be fatal. A few microlitres of their venom can kill up to 10 people.

Only about 30 recorded deaths have been attributed to the molluscs. However, they are known to be aggressive when handled and their attractive shells tempt people to pick them up.

Human victims do not appear to suffer, as the fast-acting venom also contains a painkiller that means those who have survived describe being in little pain.

Research has revealed that cone snail venom is a complex mixture of more than 100 different toxins. Some species, like the geographic cone snail (Conus geographus), also use a potent form of insulin in their venom to paralyse their prey.

However, while cone snails are deadly, they could also help to save lives. Researchers have turned to "milking" cone snails for their venom to search for new drugs in the deadly cocktails. Tiny doses have been used to treat chronic pain and epilepsy.

One toxin from the magical cone snail (Conus magus) led to the development of a painkilling drug called ziconotide, while new toxins with medical uses are being discovered all the time.

However, a 2013 study suggested that the habitats that cone snails live in are rapidly disappearing.

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