Animals Evolved To Eat Deadly Food

Check out these animals evolved to eat deadly food!

December 20, 2022・

18 min read

In nature, food rarely comes easily. Some forms of prey out there have developed pretty terrifying defense techniques to avoid becoming dinner. But apparently, nature’s most hardcore animals just don’t care.

From creatures with an appetite for the poisonous and the spiky, to some unexpected fans of all things bony and rocky, get ready for the animals that have evolved to eat deadly food.

Turtle Wipeout

Turtles may be one of the ocean’s cutest animals, but these reptiles feed on a surprisingly dangerous diet, going beyond oceanic plastic.

The leatherback turtle, found in the Atlantic, Pacific, and Indian Oceans, regularly eats stinging jellyfish, even occasionally including the box jellyfish, which possesses some of the most potent venom in the animal kingdom.

The tentacles of the box jellyfish are covered in tiny, toxin-filled cells called nematocysts, and any poor fish that comes into contact with the deadly tentacles are usually instantly stunned, killed and eventually eaten.

In humans, the box jelly’s sting causes excruciating pain on the point of contact, leading to a drop in blood pressure, difficulty breathing and even heart attacks!

Leatherback turtles, meanwhile, have no such problem. Thanks to their thick skin, particularly around their beaks, and an armored shell, these turtles are able to munch on jellyfish without having to worry about any flailing tentacles.

To provide extra safety while dinner is on the way down, hundreds of small spiny projections called papillae are lined all the way from the turtle’s throat down to their gut. These thick, resilient, semi-soft prongs help to grip the jellyfish, and give the turtle's esophagus an added cushion from any stings.

All stings considered, even the deadliest jellies end up as a pretty safe snack for leatherback turtles.

Rock-hard Stomachs

Recently, a new species of the shipworm mollusk was discovered in the Philippines, known by the locals as the antingaw, with a super weird trait.

Typically, shipworms, which usually grow between 8 and 18 inches, are known for gnawing into wood found in water, which has caused sailors some serious trouble over the years. In 1503, these pesky mollusks chewed through and sank at least two of Christopher Colombus’ ships as they ventured for the Americas.

But incredibly, the newly discovered species of shipworm munches through something even more indigestible than wood. Their go-to-dish is limestone rock!

Obviously, humans eating rocks would be an awful idea, given rocks’ indigestibility, and choking and laceration hazards as they slide down your throat. But it’s worth noting that other animals are known to swallow rocks to aid with digestion.

Some birds, such as ostriches, swallow rocks and store them in a part of their stomach called the gizzard. The muscular gizzard contracts, grinding the rocks against their stomach contents to break down their meals, making up for their lack of teeth.

But even these brave birds aren’t capable of actually digesting rocks. And even if they were able to break down limestone, for example, it’s made up of calcium carbonate, a chemical compound that would likely cause stomach pains, nausea and vomiting if ingested in large enough quantities.

But bizarrely, antingaw shipworms (Lithoredo abatanicus) not only burrow into limestone; they ingest it too! The mollusks have thousands of specially adapted flat teeth designed to help grind down the limestone into digestible chunks, before eventually pooping it out as sand.

However, nobody knows why the worms do this, as they don’t appear to gain any nutritional value from the limestone, instead getting their nourishment from bacteria found in their gills. Whatever their reasoning, if you have some antingaws over for dinner, forget key lime pie, these guys are hungry for limestone.

Bone-eating Vultures

If you enjoy food with a bit of crunch to it, you’d probably get along great with the bearded vulture. These birds, found throughout southern Europe, Africa, and western Asia, have a diet that’s 70-90% consisting of bone!

Bearded vultures crave bone, particularly the marrow inside due to its high fat content. They’ve learned to crack large bones by carrying them up a dizzy 500 feet in the air, before dropping them on the rocks below. The vultures then extract that hearty, nutritional marrow from the bone shards.

What’s more, these vultures are even capable of swallowing bones whole to ensure they get their fix of marrow. While canines chew through the odd bit of cartilage here and there, bones are indigestible for pretty much every other animal.

Luckily, these ballsy birds have evolved stomach acid with a pH of an extremely corrosive 0.7. Their sour stomachs help with dissolving bones. The acidic environment also protects these birds and other vultures from harmful bacteria, like salmonella, that are found on rotting animal carcasses that vultures scavenge.

Impressive, but remember they still have to swallow the bones in the first place. There's a good reason no other animals regularly do this. Whether it’s the risk of choking, or the threat of piercing internal organs with sharp edges, bone-eating sounds like a miserable meal.

Not that bearded vultures care. Their elastic throat is able to stretch to help swallow remains of all shapes and sizes. The inside wall of the throat is also thicker than those of other animals, preventing any piercing from sharp edges. As they say in France, bone appetit!

Long Necks, Unusual Tastes

It’s not just vultures who have a taste for bones. In a bizarre, unexpected twist, it may surprise you to learn that despite usually being herbivores, giraffes also feed off carcasses, supplying their diet with calcium and phosphorus, to grow and strengthen their enormous skeleton.

While these deceptively hardcore African mammals don’t actually swallow bones, they chew and lick them, using their saliva to dissolve all the nutrients they need.

If you thought bones were brutal, giraffes have another dangerous treat: the deadly acacia tree. Over time, this tree has developed a devilish defense in an attempt to restrain animals from grazing on them. The razor-sharp thorns of this terrifying tree can be 4 inches long, and unless an animal’s looking for a facial acupuncture, they’re usually best to stay away.

However, giraffes have a sticky solution. Using their thick lips and long, flexible tongue, coated in gloopy, protective saliva, the giraffe can remove most of the sharp thorns from acacia branches, before munching away at the twigs and leaves.

Furthermore, the acacia tree releases bitter-tasting tannins when eaten, which can bind to digestive enzymes, affecting an animal’s ability to gain nutrition from food, and proving toxic in large quantities. In 1990, 3,000 antelope died after heavily grazing on acacia trees in South Africa.

So, what about the giraffes? They are hardcore. Their saliva contains tannin-binding proteins, effectively neutralizing the tannins’ toxic effects. Only problem is, all the saliva that these massive mammals produce can lead to gallons of giraffe drool.

Unfortunately, though, drool isn’t the only gross bodily fluid that provides a vital, yet weird uses for giraffes. Their urine has some even stranger functions. Revolting as it may seem, male giraffes are willing to swallow a mouthful of a potential mate’s pee to determine whether she’s fertile or not.

Courting a non-fertile female giraffe with no chance of producing offspring would waste too much energy, so it’s quicker to just swill a mouthful of pee to test for ovulation. And they say chivalry is dead!

Spiky Supper

Giraffes aren’t the only animals who can’t get enough of the sharp stuff, be it urine or bones. The menacingly named wolf eel loves to munch on sea urchins. If you didn’t know, sea urchins are completely covered in protective spines, often laced with a venomous kick, to prevent themselves from becoming someone's lunch.

For wolf eels roaming the waters of the Pacific and Atlantic oceans, those spines don’t scare them off. They’re able to eat these spikey meals thanks in part to their large, puffy lips, which soften the blow of the spines, allowing their powerful jaws to crunch through the urchins’ tough outer layer to the meaty goodness inside.

This is all made easier thanks to their huge, intimidating teeth, which also line their throats for extra grip and crushing power. Those bizarre throat teeth also provide an easy way to turn urchin spines, venomous or otherwise, into little more than a fine powder on the way down, avoiding any nasty surprises when digesting them. Considering this creature eats spikey death spheres for fun, you’d better make sure no part of you ever ends up anywhere near a wolf eel’s mouth!

Fatal Feasts

When you think of a tasty snack, newts are probably not near the top of your list. The North American garter snake, on the other hand, frequently feeds on newts, especially when it comes to the rough-skinned variety.

However, not only does this amphibian sound unpleasant to eat, it’s also an extremely dangerous snack. This noxious newt harbors a poison, known as tetrodotoxin, or TTX, in the glands on its neck. Just one rough-skinned newt can contain up to 15 milligrams of the stuff, and it only takes 1 milligram of the toxin to kill a human.

TTX binds to membranes inside bodily cells called sodium channels, interfering with the transmission of signals from nerves to muscles. This halts the ability to control nerve impulses to perform actions, like contracting muscles. When consumed, even small amounts of TTX can lead to vomiting, diarrhea and extreme paralysis.

You’d think that would be enough to put the gutsy garter snakes off, but you’d be wrong. So how are they able to enjoy this forbidden snack? Well, to combat these toxins, the shape of the snake’s sodium channel has changed over time through evolution.

This way TTX does not bind to their sodium channels as easily, building up the snake’s resistance to the toxin. It would take around 100 milligrams of TTX to be considered deadly for garter snakes, which is the equivalent to 7 whole newts in a row.

Therefore, unless these slithering serpents over-indulge on a rough-skinned newt buffet, they’ll be fine eating these toxic treats. But newts aren’t the only deadly snack that can take a snake’s fancy.

Also, some serpents have been seen eating themselves. As snakes are cold-blooded animals, they’re not capable of controlling their body temperature through things like sweating or panting. So, a snake looking to top up its tan can quickly overheat, affecting the way a snake's brain functions and leading to confusion.

As a result, they occasionally become excessively hungry, and mistake their own flicking tails for a prey animal. If they don’t cool down and come to their senses, snakes can actually eat themselves to death, either through blood loss, infection, or suffocation.

The Rat’s Revenge

Snakes aren’t the only animal to develop an appetite for deadly amphibians. The rakali, otherwise called the water rat, is known for making a meal out of poisonous cane toads.

If a human were to chow down on one of these toads, the ingested poison, called bufotoxin, would initially cause vomiting and diarrhea, and within an hour, the symptoms would intensify. The heart may begin to beat irregularly, failing to pump blood around the body, possibly proving fatal.

As the conniving cane toad was only introduced to Australia in the last century, many native animals there haven’t adapted to these poisonous powers either. For example, since the introduction of cane toads in the 1930s, the population of yellow spotted monitor lizards, a predator of the cane toads, has dropped by 90% due to fatal feasting on the poisonous toads.

But, unlike these lizards, Australia’s native rakali water rats won’t go down without a fight or a feast! They’ve devised an ingenious method to snack on the devilish toads, without the deadly side-effects.

To feast, the water rats flip the toad over, before slicing the chest open with their teeth. They do this to target the least poisonous parts of the cane toads, removing and eating the heart and liver. Sort of like nature’s version of ‘Operation’.

This way, the water rats avoid ingesting too much bufotoxin, which is mostly found around the neck glands and on the skin. That takes the saying ‘eat your heart out’ to the next level!

Boozy Shrew

Not all dangerous meals of nature look hazardous at first glance. Take the Bertam palm tree. This flora, found in the depths of the Malaysian rainforest, doesn’t look too dangerous but the potent nectar of this tree's flowers is capable of intoxicating humans.

Though, not quite in the same way as we’ve seen so far. The flowers of the Bertam palm naturally contain populations of yeast, and this yeast ferments the palm’s nectar, which ends up possessing a 3.8% alcohol concentration, the same as a light beer!

The pen-tailed tree shrew has a love for this boozy nectar, and despite only weighing a few pounds, these little guys drink the equivalent, adjusted for their tiny body weight, of 10 glasses of wine per night!

If a human were to consume as much alcohol as the pen-tailed shrew every night, it would quickly cause liver disease, heart failure and alcohol poisoning, possibly even death!

The shrews are unperturbed, however, and seek out the pungent, yeasty nectar due to its high sugar levels. You’d think the boozy behavior of pen-tailed tree shrews may lead to them stumbling around the jungle, or wishfully texting their crush.

However, the small shrews show no ill-effects from ingesting the alcoholic nectar, not even appearing to get drunk. So what’s their secret?

It’s down to the shrews ability to effectively modify alcohol toxins into less toxic substances. The tree shrew converts much of the alcohol they ingest into a non-intoxicating by-product of alcohol called ethyl glucuronide, or ETG, which ends up in their fur.

Turns out they’re much more effective at this than other mammals, like us. As such, the hairs of the pen-tailed tree shrew contain 30 times the amount of ETG that would be present in a human that drank alcohol excessively.

And here we were thinking us humans had the monopoly on drinking booze. The boozy pen-tailed tree shrew: that’s a real party animal.

Massive Mouthfuls

How do you like your eggs in the morning? With a kiss? Boiled? Scrambled? Probably not swallowed whole, unless you’re an egg-eating snake. These toothless reptiles feed exclusively on eggs, swallowing their meals whole, even when the egg is four to five times wider than the snake’s mouth.

The snake’s jaws are not fused together like ours, instead being connected by an elastic ligament, allowing their mouth to open 150 degrees. It’s then a slow process of forcing their stretchy body over the egg.

While this process is going on, snakes use a movable opening in their mouth called a glottis to breathe, which can be maneuver around to enable airflow, despite the huge mouthful.

After the meal has been successfully swallowed, egg-eating snakes rely on strong muscles and bony protrusions in their spine, which puncture and crush the eggshell, releasing the contents for digestion.

Similar to snakes, frogs also swallow their food whole, but rather than eggs, they usually favor insects and other small prey.

Most frogs have no teeth either, but rather than widening their jaws, they, strangely, use their eyes to help swallow food. When the prey is in the frog’s mouth, their eyes retract, providing additional force to guide the unfortunate victim down the frog’s throat.

Thanks to the fact that frogs can breathe through their skin, choking is rarely an issue, so a big meal is always on the cards. But in the case that a frog does fully swallow something too big, or something that proves poisonous or troublesome, the amphibians have developed an unbelievable response.

Forget vomiting; frogs and toads, for that matter, eject their whole stomach. Their front feet wipe away the unwanted prey, before they swallow their stomach back up again, and all because they don’t have the ability to vomit in a conventional sense!

But it’s not just reptiles and amphibians with the unique tools to handle their big, big appetites. The black swallower fish is found at depths of over 2.5 miles in the Atlantic Ocean and is the true king of All-You-Can-Eat buffets.

Food is so scarce in the deep sea, that when the black swallower eats, it has to feast. With large, flexible jaws, it swallows large fish whole, into a stomach so stretchy that it can ingest food twice its own size and ten times its weight!

Even still, its eyes can sometimes be larger than its belly and that’s saying something! Occasionally, determined prey can bite or pierce holes through the black swallower’s stretchy, yet thin stomach, killing the greedy fish in the process.

What’s more, if they eat a meal too large, the fish inside the stomach can decompose before the swallower has had time to digest it. Gas released from the decomposition can force the black swallower to float up to the ocean surface, where it dies due to the severe changes in pressure upon its body!

Gassy Worms

At even lower depths than where the black swallower binges, you'll find giant tube worms. These creatures somehow survive along hydrothermal vents, 8,000 feet below the Pacific Ocean’s surface.

These vents spurt out seawater heated by hot magma, the released fluid reaching a spicy 700 degrees Fahrenheit. Fortunately for giant tube worms, the near-freezing sea water in the deep ocean quickly cools the temperature of the fluid ejected from the hydrothermal vent before it can damage them.

It’s one thing to not get burnt, but what exactly can something eat at such depths? Well, giant tube worms have no mouth, and don’t technically eat at all. Instead, they have what’s called a trophosome, an organ filled with bacteria which provide them with energy through a truly bizarre means.

The hydrothermal vents around which the worms live emit a high concentration of hydrogen sulfide. This gas is toxic to most animals, including humans. Exposure, even to low levels, of hydrogen sulfide will burn your eyes, and if breathed in, can cause headaches, memory loss and severe nausea.

Luckily for tubeworms, the bacteria inside their trophosomes use the hydrogen sulfide as an energy source, through a process called chemosynthesis. This typically converts hydrogen sulfide, water and carbon dioxide into glucose, which the tubeworm then feeds off.

A koala-ty Snack

With their lovable looks, you’d never expect that Koalas indulge in a deadly diet. But it’s true and it all comes down to eucalyptus. For most animals, feasting on the leaves of the eucalyptus tree isn’t a risk worth taking.

The leaves of the plant contain eucalyptol, a substance that in its pure form is deadly to humans in doses as small as 3.5 milliliters. Considering that koalas get through about 500 grams of these leaves per day, you’d hope that they’ve evolved to ingest the toxic leaves.

And, technically, they have but it’s a little more complicated and frankly, bizarre, than that. Koalas possess an unusually large presence of detoxifying enzymes, useful gut bacteria, and a very well-adapted digestive system, allowing them to break down and flush out eucalyptol toxins that would normally be deadly to other animals.

However, in a head-scratching twist, baby koalas aren’t actually born with this ability to safely digest eucalyptus, despite it being almost all they eat. Before the baby koala can feast on eucalyptus leaves, they need to feed on pap.

However, “pap” is in fact poop from mommy koala. But not any old poop; this is a mushier form of excrement, which is vital to the joeys development, containing the crucial gut bacteria required for safely digesting eucalyptus. And you thought human baby food was gross!

Cacti-eating Camels

Whether it’s the desert’s scalding heat, or the lack of food and water, only the strongest animals survive. Camels, for instance, are able to withstand the ferocious rays of the desert sun and they’ve also evolved to find food where there doesn't seem to be any.

There is food in the desert, as long as you are happy eating viciously spiked cacti like a camel. The threat of having 6-inch thorns pierced around your face is enough to put most animals off messing with these succulents, but camels are perfectly suited to tackle such a prickly plant.

Their mouths are full of cone-shaped papillae, somewhat like those found in leatherback turtles. For camels, the resilient, flexible papillae prevent most of the cacti spines from piercing the more tender parts of their mouth.

While eating chunks of cacti, camels orient them at the side of their mouth, rather than trying to swallow them straight down, making the sharp spines much more manageable. Unfortunately, though, not all animals have evolved such ingenious cactus-eating techniques.

Despite having no good reason for trying, countless cats have been witnessed by their owners nibbling on cactuses. If you ever happen to see your little feline friend sampling a cacti, don’t be too alarmed. They’re most likely bored, testing out new textures for fun.

But to be safe, try to make sure your cat has plenty of sources of mental stimulation available, and keep your cacti out of reach, just to make sure your cute kitty with camel-like aspirations doesn’t get a spiky meow-full.