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Some animals are dangerously cuteā€”and we mean that literally. Some of these critters like cute enough to cuddle, but with secret deadly defenses. Join Michael Aranda for a new Animal-centered episode of SciShow!
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Poison dart frog:
Slow loris:
Spiny mice:
Sea otters:
Moon snail:

Poison dart frog:
Slow loris:
Spiny mice:
Sea otters:
Moon snail:

[SciShow intro plays]

Michael: Why do some people squirm at the sight of a centipede and “squee” at the sight of a panda? We tend to think animals with big eyes, chubby bodies, and clumsy demeanors are cuter than others.

Evolutionarily, our love for baby-like features could stem from our own parental instincts: it makes us nurture our offspring, so they have a better chance of surviving. And this protectiveness can extend to other cute animals too... even though it can blind us to the reality of nature. Animal behaviors designed for survival can make these seemingly-cute creatures kinda scary.

Pufferfish are pretty cute, right? They have large, buggy eyes and they swell up with water like an adorable balloon! But the “puff” in pufferfish is actually a warning. Their pointy spines are mostly for show, but the message is clear: “HEY, DON’T EAT ME! I’M POISONOUS!” This poison is called tetrodotoxin, and it’s produced by bacteria that naturally live in the pufferfish's skin and organs. And when ingested, it’s 1,200 times more poisonous to humans than cyanide.

See, tetrodotoxin is a neurotoxin, something that affects the nervous system. Our brain cells and muscle cells are powered by the movement of sodium ions through protein channels in the cell membranes. And tetrodotoxin blocks these sodium channels, which can cause vomiting, diarrhea, paralysis, or even death in humans.

We currently don’t have an antidote for tetrodotoxin poisoning, although there are some natural predators of pufferfish that are resistant to it. Even with these dangers, pufferfish are a very carefully-prepared Japanese delicacy known as fugu. At low doses, tetrodotoxin just gives a consumer a tingling sensation or light-headedness.

So, for some foodies, eating this cute fish can be worth the risk. Poison dart frogs are adorably tiny, bright, and colorful... and very deadly. Their name comes from the fact that indigenous hunters laced darts with the toxins excreted from the amphibians’ skin. Different poison dart frog species have different toxins, but they’re all in a group of chemicals called alkaloids.

Alkaloids have a range of effects: like, morphine is a depressant and used as a painkiller, and nicotine is the addictive stimulant found in cigarettes. When the strong alkaloids found in the skin of poison dart frogs enter the bloodstream, they act as neurotoxins, like the pufferfish’s tetrodotoxin, and alter the sodium channels that control the cells of the nervous system.

The frogs don’t produce the toxin themselves, but they get it from toxic ants, beetles, and millipedes that they eat. Somewhere along the evolutionary tree, poison dart frogs started storing these toxins in their skin as a defense mechanism, and scientists are still trying to figure out how they do it. Mother frogs even pass down poison to their babies, so that little tadpoles have a greater chance at surviving out in the world. Plus, scientists have found that the brighter-colored frogs tend to be more toxic. So no matter how cute they seem, the patterns and colors on the poison dart frog are just a bright warning sign to predators.

The slow loris is arguably one of the cutest primates, they’re nocturnal and evolved to have adorably giant eyes to improve their vision at night. But their huge eyes and facial markings may also be a defense mechanism... by mimicking the features of a king cobra. This is an example of Müllerian mimicry, when two species have the same behavior or appearance to protect them both from a shared predator, in this case, a hungry bird of prey. While king cobras are still preyed upon by hunting birds, their venomous bite serves as a good defense. Slow lorises can mimic king cobras by making a hissing sound.

But here’s the more terrifying similarity: they’re the only primate to evolve a toxic bite. And the slow loris toxin isn’t produced in their mouths. They have a special gland under their arm that produces a toxic oil, that’s activated when mixed with their saliva. The proteins in this toxic cocktail are actually similar to those found in cat dander, which can cause a strong allergic reaction or anaphylactic shock. So after a couple licks, slow lorises are ready to defend themselves against predators.

They also lick the heads of their young to give them a protective layer of toxin, because they don’t have the dexterity or speed to protect themselves yet. So if you happen to see a slow loris grooming his underarms, you might just want to back away.

The platypus has a pudgy body, duck-bill, and stubby webbed feet that makes awkward look cute. You might think they’re unique because they’re an egg-laying mammal, but they’re also a venomous mammal. Male platypuses are equipped with spiny venomous spurs hidden behind their webbed feet. How’s that for a secret weapon?

It’s possible that the platypus uses these spurs to defend against predators, but during mating season, the venom gland grows and produces more of the toxin. And since only males develop these venomous spurs, they could’ve evolved them to compete for mates.

A male platypus fights by wrapping his hind legs around his foe and driving in his spurs, kinda like a cowboy on a horse. Then, proteins in the injected venom cause pain and temporary paralysis, leaving the weaker platypus unfit to mate. The dominant male gets the female, and will hopefully pass on his genetic traits to the next generation of duck-billed fighters.

Mice are usually written off as vermin, but they can be really cute. Look at those big round eyes and that furry little body! But be careful when you go to pet an African spiny mouse. When provoked, these mice shed their skin right off of their body, leaving a gaping wound. Impressively, the mice can regenerate their skin cells within days, and their furry coat returns to normal after a month.

Our furry friends like dogs and cats may shed a couple times a year, but this spiny mouse behavior is actually more similar to reptile autotomy, or self-amputation. That’s the self-defense mechanism where a lizard loses a tail or a starfish loses a limb to get away from predators, and then regenerates it later. These mice are the first mammals known to display this type of regeneration behavior. While it might seem kind of creepy, these mice can teach scientists a lot about wound healing in mammals, and give us new ideas for medical care in humans.

Dolphins are loved by lots of people... and what’s not to love? They’re cute, playful, and extremely intelligent. But competitive mating behavior is common in the animal kingdom, and male bottlenose dolphins are no exception. They will aggressively fight each other and leave huge teeth gouges in each others’ skin. And even though dolphins are social animals and swim around in groups called pods, less aggressive males can be kicked out when they lose a fight.

The most brutal behavior is infanticide, or killing of newborn baby calves. After a female gives birth, she’ll usually focus her energy on tending to her calf. The mother-calf bond is really strong, and a young dolphin will stay with the mother and continue to nurse for about 4 years. However, if the calf dies, the female becomes ready to mate again within a week.

So some males will follow a pregnant female until she gives birth, and will kill the calf shortly after, to ensure they have a female to mate with, and pass on their genes. This is a common practice among many animal species, but it seems especially vicious when you think about dolphins.

Sea otters are another playful creature of the rivers and ocean, who seem to be synonymous with cuteness. Like, they hold hands when they sleep! How cute is that?! But competitive evolutionary behaviors can make even the cutest critter seem like a little monster. Male sea otters participate in hostage behavior, basically, stealing an otter pup from it’s mother, and holding it ransom for food. Males are extremely territorial about resources, and are more likely to be aggressive toward other otters to get what they want.

Not only that, but sea otters need lots of food to keep themselves warm in the cold waters, and female sea otters need even more food to care for their newborns. Because of all this competition over resources, a new mother might either stop nursing her pup too early or completely abandon them, just to keep herself alive. However, there are conservation efforts that strive to protect and care for sea otters, even if they don’t always care for each other.

Kinda like the platypus, ducks are an unconventionally awkward-cute animal. Their chubby bodies, stubby legs, and clumsy waddle can bring a smile to anyone’s face. But their mating behaviors... get weird.

Most birds reproduce using anatomical organs called cloaca, a single opening where the digestive tract and reproductive tract meet. However, male and female ducks have been in an evolutionary battle over time. Male ducks, like other animals, have a competitive drive to mate, so they evolved corkscrew-shaped phalluses with ridges and spines to forcefully mate with females. However, female ducks evolved to defend themselves against aggressive males – their vaginas are also corkscrew-shaped... but they twist in the opposite direction! Plus there are even “dead ends,” kinda like a biological labyrinth.

When a lady duck finds a partner she does want to mate with, she can relax her spiral reproductive tract to make mating much easier. So, in this battle of the sexes, it’s the females that rule!

Have you ever found an empty shell on the beach with a perfectly tiny round hole in it? This could be the work of the moon snail. Snails can be cute because of their chubby, squishy appearance. But what they lack in size, moon snails make up for by being voracious predators. Moon snails primarily feed on clams, but also eat other kinds of mollusks, crabs, and even other moon snails.

Snails have a feeding organ called a proboscis, kind of like the one a butterfly uses. At the tip of the proboscis, moon snails have a radula, which is a structure lined with rows of tiny sharp teeth. They use their radula to bore a tiny hole in the shell of their prey. Then, a specialized gland releases digestive enzymes and hydrochloric acid through the proboscis into the body of it’s prey, which dissolve the soft tissue inside. And once their prey is reduced to a goopy mess of nutrients, the moon snail can then reach into the hole with its proboscis and slurp up its hard-earned treat.

Ladybugs, or lady beetles, are tiny, with bright colors and a spotted pattern that makes them especially cute. Even an amateur gardener knows that ladybugs are carnivorous, with a preference for feeding on aphids. But, like many animals, the behavior of lady beetles is greatly affected by food... and it can get kind of vicious.

When there are lots of yummy aphids around, ladybugs tend to mate more frequently. However, several species of ladybugs are also really prone to sexually-transmitted diseases, some have up to an 80% chance of passing on an infectious species of mites after mating. These mites feed on the female’s hemolymph, which is its circulatory fluid, like our blood, and can leave them infertile.

Plus, when food sources are scarce, lady beetles can turn to cannibalism, feeding on eggs, larvae. This is an inherited trait that can be passed onto their young, which means more cute little ladybugs with cannibalistic tendencies.

So animals can be cute, but you have to remember that they’re still animals with adaptations for defense and survival. We can just appreciate the diversity in the animal kingdom, the cute ones, the terrifying ones, and everything in between.

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