They say it’s a dog-eat-dog world out there and that’s just if you’re a dog. They’re cute and can get away with simple things like that. Other creatures are not so lucky so when it comes to self-defense they need to up their game. While most animals in the world rely on things like teeth and claws, camouflage, speed, or subterfuge for defense, a few take things to the next level. Some have even resorted to biological methods of modern warfare with projectile and explosive weaponry.

10. Bombardier Beetles Shoot Boiling Chemical Bombs

You can’t talk about creatures that employ artillery as a defense mechanism without mentioning the bombardier beetle. These tiny bugs pack a full-on chemical weapon punch for anything foolish enough to eat them that is reminiscent of the premise behind the explosives used in Die Hard with a Vengeance, which gives the beetle tons of extra street cred.

Inside the beetle’s abdomen are two sacks. One contains hydrogen peroxide. The other is hydroquinone. You’re probably familiar with hydrogen peroxide as most of us have it in a medicine cabinet or first aid kit. Hydroquinone is also used cosmetically as a skin-lightening agent that reduces melanin. They’re typically pretty safe, too.

When the beetle is threatened, it shoots these chemicals out of its backside mixed with a third compound that acts as a catalyst and causes an instant chemical reaction. The two normally benign chemicals mix and form boiling water and benzoquinone. The spray and gas mixture hits the beetle’s target at 212 degrees Fahrenheit or 100 degrees Celsius, the temperature of boiling water.

Small creatures like other insects will be killed immediately. Larger creatures can be blinded and even a human will be burned and scarred. This is because of the temperature but also the caustic nature of the chemicals which can affect the respiratory system, as well. 

The beetles have enough juice to fire off about 20 bursts before they run out and they’re also known to have impeccable aim. The orifice through which they fire the mixture has a full 270 degrees of movement to aid in aiming at predators, too, meaning there aren’t a lot of safe ways to come at a bombardier beetle.

9. Velvet Worms Shoot Slime From Biological Gun Turrets

In the animal kingdom, being blind doesn’t mean you can’t shoot your shot when it counts. Velvet worms live in forests and jungles around the world and there are over 200 species of them. They have developed a unique defensive ability which has been described as a “silly string of death,” so you know it has to be good.

The worms feel changes in air currents to know when prey is nearby and then, when they get close enough, two nozzles extend from their head to fire foot-long ropes of goo. The substance coats its target and dries quickly, rooting the victim in place. It can also be used defensively to escape a predator, either holding a small predator in place or, at the very least, slowing one down as it deals with a face full of fast-drying sludge. 

Once trapped, the worm can approach its prey and use a knife-like protrusion in its mouth to slice a hole in it. They then fill the trapped snack with digestive saliva which will liquify it and allow the worm to slurp it up instead of doing anything messy like chewing. 

8. Hagfish Expel Slime That Expands 10,000 Times

The velvet worm may think he’s hot stuff with his little slime ropes but the hagfish is the unparalleled slime goat of the animal kingdom. These off-putting creatures have no jaws, no spines, live on the ocean floor, and have changed little in 500 million years. But none of that is why they’re famous.

When threatened, hagfish produce slime. It’s a defense mechanism meant to fend off a predator to prevent the fish from being eaten. So far so good. But the hagfish slime is unlike anything you can imagine. Their bodies are covered in glands that expel mucus and miles and miles of thread-like compounds to ward off predators. As soon as this stuff hits the seawater it expands at a staggering rate. The slime will grow 10,000 times in an instant, turning the water into Jell-O in the blink of an eye.

If a predator is trying to eat a hagfish, it will have to immediately back off or deal with suffocation as its mouth and gills are overwhelmed with sludge it can’t breathe and can’t escape. Not only is the substance incredibly soft it’s stretchy and remarkably strong, so you can just break through it to get free. 

7. Sea Cucumbers Shoot Internal Organs From Their Anus

Sea cucumbers aren’t winning any beauty contests soon but they do attract a lot of attention for their unusual self-defense strategy. They use their butts as a cannon and fire out their insides.

There are variations in how this works depending on the kind of sea cucumber. Some of them shoot out internal organs, kind of like a fighter jet releasing flares to attract enemy missiles, that will then grow back later. Others fire off strands of a sticky substance that can snare their potential predators while the cucumber escapes.

In the latter case, the threads released are called a Cuvierian organ. These tubes are attached to the organs the cucumber uses to breathe, which they do through their butts. If a predator comes along and tries to eat the cucumber, the organs are ejected and expand as they fill with seawater.

Because they’re sticky like a spider web, they can snare the attacker and sometimes even kill it if they can’t break free.

6. Texas Horned Lizards Shoot Blood Out of Their Eyes

Sometimes looking hardcore and dangerous is not enough to convince a predator to leave you alone. The Texas horned lizard, for instance, looks like a dangerous little foe for any predator. His back is covered with those aforementioned horns making it look like a modern-day dragon. It’s also really well camouflaged when hiding in sandy, rocky areas in and around its habitat. But it still has a hidden defense in case horns and hiding don’t work. 

Because horned lizards are pretty small, about the size of a bullfrog, they are vulnerable to larger predators even with their spikes. To fend off these creatures, the lizard will shoot a jet of its blood out of its eyes, like some kind of horror movie come to life. 

When threatened, blood flow to the lizard’s head is restricted. This causes the ocular sinus to fill as the pressure builds. The lizard can then contract the muscles around its eyes and cause the sinus to burst outward, shooting a jet of blood as far as five feet. They can do it multiple times as well. 

Few animals like being squirted, just try squirting your cat with a water bottle sometime, so the tactic can be fairly effective. Also, the blood apparently tastes bad, so it helps convince predators to move on. 

5. Northern Fulmar Gulls Use Vomit As a Defense

When it comes to forcibly firing something at a predator or prey, biology only gives us so many options. Whatever is being shot has to come out of some sort of orifice and most life forms only have so many to choose from. With northern fulmar gulls it’s the mouth. And the ammunition they fire comes from the most obvious place you can think of – the stomach. These gulls have weaponized vomit.

The stomachs of the fulmar gulls contain an oil that is described as being both foul and sticky, so we’re off to a good start. If a predator bird comes to their nests, the birds can vomit on them to force them away. But their use of this weapon is more insidious than just being disgusting. 

When the gulls vomit on other birds, it strips away the coating that sea birds need on their feathers to stay afloat. It can also mat the feathers in such a way that the bird can no longer fly, which is essentially a death sentence for any bird. 

4. Archerfish Shoot Prey With Water Jets

We’ve already covered a couple of underwater creatures that have fired off effective defenses while being submerged, but the archerfish is a little different. While it lives in the water like any other fish, its weapon is meant for prey on the land and in the air. 

Described as an “anti-aircraft gun,” the archerfish can fire a jet of water into the air to knock prey from the sky or from off of plants hanging over the water. Once the prey falls into the water, the fish can swoop in and swallow it whole.

The fish are just a few inches long so their prey isn’t particularly big – usually just tasty-looking flies or crickets. But the archerfish can spy them from the depths, rise to the surface, and fire off a jet to a distance of several feet with amazing accuracy so much so that they can tag insects in flight. 

Even if the aim is a little off, the archerfish is working with an automatic weapon. On a single mouthful of water, it can fire up to seven shots in quick succession to hit its target. Studies have shown that the fish likely won’t need this, though, since they rarely miss.

3. Spitting Spiders Spit Silk at Prey

Arachnophobia is a common fear among humans and you have to assume smaller insects are terrified of spiders as well. The webs and the venom make them formidable predators. The only upside is that many of them are passive and even the aggressive ones need to chase prey. Except for spitting spiders. 

As the name suggests, spitting spiders can fire off a spit attack at prey. The spit attacks travel at 30 meters per second which is over 67 miles per hour. It snares the prey with silk, trapping it in place so the spider can quickly inject it with venom. 

2. There’s An Exploding Species of Termite

In the jungles of French Guiana, there’s a species of termite that spends its entire life waiting to die. Philosophically, you could make that argument about any living thing. But these guys take it to an explosive new level.

As these termites age, their body secretes a blue liquid produced by a pair of specialized glands. The liquid crystalizes in an abdominal pouch and it just stays there. More and more of it builds up as the termite ages such that the oldest termites will have an unhealthy dose of this stuff that they may never use. But then again they might.

If the colony is attacked, the oldest termites become the front line of defense. Because they’re older, these termites are less useful to the colony as foragers and workers. Their mandibles dull over time, making them slower and less useful. But their blue crystals give them value still.

When threatened, the termite can force their pouch full of crystals to explode. It mixes with their saliva to create a toxic solution that can paralyze and kill attacking termites. The older the termite, the more potent the reaction and though the termite also dies, it does so to protect the younger members of the colony. 

1. Pygmy Sperm Whales Shoot Poop Clouds

Whales rarely have a lot to worry about in terms of predators, except for humans. In the wild, few animals challenge a whale simply because of its size. But that only counts for large whales and not all of them get to monumental size. Take pygmy sperm whales, for instance. At eight to 14 feet they’re not outside the range of what a shark or orca whale might attack. 

To escape predators, pygmy sperm whales have evolved a unique sort of smoke bomb defense. Except instead of smoke it’s poop. Inside their intestines is a sack filled with a dark, reddish-brown liquid. In a pinch they can shoot out three gallons of the sludge which produces an ink cloud like a squid, giving the whale time to flee.

When imagining a picturesque medieval landscape, it’s nearly impossible not to also visualize a castle somewhere in the background. And while it’s true that various types of fortifications have been around since ancient times, it was during the medieval period that castles truly came into their own. 

But what most people don’t know about medieval castles – particularly those in Europe – is that they were typically private fortified residences for local feudal lords or nobles. Depending on the circumstances, these castles played both a defensive and offensive role, as well as providing administrative and domestic functions. It should also go without saying that castles also acted as status symbols, projecting power in the surrounding region. 

In this list, we will be looking at some of the most ingenious and effective castle defenses from around the world.

10. Natural Defenses

One of the most important things to consider when building a castle is choosing a location that can take advantage of as many natural features as possible. You want to make it very hard for the enemy to besiege you. Building a fortification on high ground is always a good idea. Not only does it extend the height of the walls in relation to the enemy army, but it also forces them to charge uphill, slowing them down and making it difficult, if not impossible, to bring siege equipment up close. 

Motte-and-baileys were some of the earliest examples of castles in the true meaning of the word. They were popular during the 11th century, particularly in France and Norman England. The keep, which was the primary defense element of the motte-and-bailey castle – and the home of the local lord – was situated on top of a steep hill or earthen mound known as the motte. Rock outcrops are even more effective for castle defense purposes but required more time, energy, resources, and know-how to build and maintain. 

Another great place to build a castle is next to a river, particularly a river bend. This provides a natural defense system that can be artificially extended to surround the entire castle complex. Building on an island in the middle of a lake has the same effect. These types of castles built next to rivers or lakes also had the added benefit of providing a steady source of fresh drinking water. Castles built on high hills or rock outcrops often had incredibly deep wells to have a water source inside the walls. Kyffhäusen Castle in Germany, for example, has a well that goes roughly 577 feet deep.  

9. Rusticated Walls

Also known as bossing, rustication refers to building stones that are left rough and uncut on the external facing side of a wall. For many years, historians have debated why some of the masons of old used to do this. Initially, it was believed that rustication was simply a technique to save both time and construction costs. Some have even speculated that it gave the fortress a more menacing appearance. And while these were definitely a benefit, it turns out that bossing also had a more defensive purpose.

Historians have figured out that rusticated stone walls were far better at dissipating the energy of a high-speed projectile like the ones fired from a catapult, trebuchet, or other ancient or medieval artillery. The uneven surface of the rusticated stones prevented the direct energy transfer of the projectile into the wall. It’s somewhat similar to how spaced armor works on modern tanks. 

Rusticated masonry predates Ancient Rome and has been in use on many castle walls up until the proliferation of gunpowder and cannon fire. 

8. Hoardings and Machicolations

Hoardings, sometimes called hourdes, are wooden defensive structures built on top of stone or brick walls. These take the form of a roofed porch suspended on perpendicular supports. The purpose of hoardings is to provide the wall defenders with a better angle of firing down on attackers located at the base of the wall.

They have window-like openings along the breastwork to shoot arrows or bolts, as well as holes in the floor to throw rocks or other projectiles at the enemy soldiers hugging the base of the wall. Without these hoardings, defenders would have to overexpose themselves in order to fire at the enemy directly below. 

In times of peace, hoardings would be taken down and stored away as prefabricated sections. Once a threat presented itself, they would mount them atop the walls and cover them in fresh animal skins, which would keep them from being set ablaze.

Machicolations are similar in purpose to hoardings, the main difference being that they’re permanent and made out of the same material as the wall itself. Although requiring a more sophisticated level of engineering and higher expense, machicolations are permanent, cannot be set on fire, and are resistant to crossbow bolts and even heavier artillery projectiles. 

During the 19th and 20th centuries, when warfare changed significantly, machicolations were used solely for decorative purposes, as seen in the Gothic Revival architectural style. 

7. Crenellations and Arrow Slits

If you picture a medieval castle wall, chances are that you’re seeing it crenelated. They’ve been in use since ancient times, with the earliest known example being the Medinet-Abu palace at Thebes in Egypt. They’re also present on the Great Wall of China and many other fortifications.

Also known as battlements, crenellations are comprised of merlons, which are the projections on top of the wall. The crenels are the cut-out portions in between the merlons. Although they don’t seem like much at first glance, they provided excellent protection for the defending soldiers.

They would use the merlons to hide behind while firing arrows, crossbow bolts, or throwing rocks through the crenels. Crenellations were not often built on the inner side of the wall – particularly curtain walls – in the event the enemy managed to scale them and use them against the defenders.

Some medieval castles even had merlons with built-in arrow slits for added protection. The invention of arrow slits is attributed to Archimedes during the 214–212 BC siege of Syracuse but there’s a chance that they may be far older than that. And although they were used by the Ancient Greeks and Romans, they were only reintroduced in the late 12th century by the Normans.

On the outside, arrow slits are vertical and very narrow for protection. On the inside, however, they widened up so as to provide the archer or crossbowman with as much firing range from side to side and close to the base of the wall as possible. In later centuries, these were redesigned into cannoniers. They’re basically the same thing but for cannons.

6. Heavily Defended Gatehouses

Gates are a natural weak point in any fortification and it’s the defenders’ job to reinforce any such weakness the best they can. They’re basically a hole in the wall, after all, and had some of the heaviest defensive features of the entire castle complex. It’s also important to note that these weren’t just simple gates but gatehouses. They were multistory buildings that also happen to have a passageway running through them. 

In many cases, it was a challenge even getting close to the gatehouse as an attacker, especially with a battering ram. Depending on the castle, you’d have a water-filled moat or a deep ditch with a drawbridge. Alternatively, you’d find a steep or sharp bending path leading up to the gate, which made it difficult, if not impossible, with a battering ram.

Most gatehouses also came equipped with two flanking towers, providing a better angle on the gate. These allowed archers and crossbowmen to shoot at the enemy right next to the gate. Brattices, which are essentially miniature machicolations, were also built right above the gate to throw rocks down on the attackers.

The main feature of a gatehouse was, of course, the gate itself. They had to be relatively easy to open and close in times of peace, meaning that they were typically made of wood. To strengthen it, the defenders often used both vertical and horizontal layers of sturdy, hardwood planks, as well as metal plate reinforcements on occasion. 

Most gatehouses also came equipped with two or more portcullises. These are wooden and/or metal lattice grills that dropped quickly, locking firmly into holes in the ground. If the enemy managed to break down the gate and entered the passageway inside, the portcullises would be dropped shut, trapping the enemy soldiers inside. Oftentimes, there were arrowslits on the side walls inside the gatehouse, as well as murder holes above. Boiling water or hot sand, not oil usually because oil was rare and expensive, was dropped through these murder holes on the entrapped enemy. 

5. Barbicans

Also known in the castle-building business as a “death trap,” barbicans were an added layer of defense leading up to the castle’s main gatehouse. Barbicans can take on numerous shapes, but the most common was in the form of a narrow passage, called “the neck,” and one or more secondary gates leading up to the main entrance. As the charging enemy army rushed towards the main gate, they were being funneled down this passage, making them easy pickings for archers and crossbowmen.

Other variations of the barbican included a tower situated over a bridge or a walled semicircle in front of the moat and drawbridge. Castles could have multiple barbicans defending the main entrance. With improvements in artillery technology during the 15th and 16th centuries, they became obsolete. 

Barbicans were also used in Beijing, China, guarding the many gates to the capital city during the Ming and Qing dynasties. They were demolished during the 1960s, along with most other of the old city’s defenses, to make room for modern roads, subways, and other urban developments. 

4. Elephant-Proof Gates

Battering rams, in various shapes and sizes, have always been used as an effective method of breaking down fortified gates. Even to this day, they remain an invaluable tool used by police, military, and other special forces. In medieval India, elephants made for great and effective battering rams. 

The defenders had to compensate for these mighty beasts of war breaking down the main entrance by mounting heavy spikes on the gates. When one or more elephants charged directly at these gates, they would do so with their forehead, which was protected by a steel plate. The defenders would usually mount spikes at the average height of an elephant’s forehead. Some of these spikes would also come with hooks, preventing the elephant from retreating and making it a stationary target for the defenders on top of the wall.  

3. Mazes

Due to their location along the so-called Ring of Fire surrounding the Pacific Ocean, Japanese castles have a different construction than those in Europe and other parts of the world. Instead of relying too heavily on brick and mortar, Japanese castle keeps are made primarily out of wood and are located atop a motte of large boulders held together by steep stone walls. Unlike its European counterpart, the Japanese castle design is far more earthquake resistant. This design can also better facilitate the incorporation of mazes as part of its defense system.

Built and expanded during the Warring States Period in Japan, Himeji Castle – the largest in the country – sports some of the highest walls at 85 feet tall, as well as a whopping area of over 576 acres. Its walls also tend to flare out at the top, making them even harder to climb. Alongside other defenses such as several concentric moats, machicolations, or hidden rooms designed for surprise attacks, Himeji has its entire castle complex turned into an intricate and highly confusing maze. 

Its purpose was to defend the castle’s main keep from large armies by leading them through often steep, narrow, and winding paths. These will often branch out, leading attackers to deadends or facing dozens of strong iron gates, as well as narrow passageways. Constantly flanked by high walls, the invading army would find itself under fire from the defenders. For better or worse, Himeji Castle’s walls were never breached and its labyrinth was never put to the test. 

2. Clockwise Spiral Staircases & Trip Steps

When building defenses for a medieval castle, architects and engineers needed to use everything to their advantage. And in some castles around Europe, they used the attackers’ propensity to wield weapons right-handed against them when building spiral staircases. If the enemy managed to breach inside and started going up towers or the castle’s keep, they would sometimes have to do so on a clockwise spiral stairwell.

This gave an advantage to the defenders who were usually fighting down the stairs. As the majority of soldiers wielded their weapons with their right hand, meant that their sword-wielding arm was constantly blocked by the inner wall. Therefore, attackers going up had to completely expose themselves to be able to use their weapons effectively. 

The defenders, on the other hand, didn’t only benefit from the bottleneck provided by the staircase, their higher ground position, and the attackers’ disadvantage of having to constantly expose themselves, but also use the inner wall as a partial shield.

Trip steps were also a somewhat common occurrence in medieval castles like is the case with Berkeley and Hever castles in the UK. In both examples, some of the steps are uneven by having a different depth than the others. And while this may give the impression of poor craftsmanship, they were, in fact, deliberate. 

Over time, the inhabitants would become accustomed to these trip steps and would instinctively adjust their walk. Attackers, however, were unaware and in the heat of battle would often lose their footing, stumble, or even fall, giving the defenders a slight, but possibly critical advantage.

1. Secret Passages, and Exits

Since castles were typically the private residence of a noble or local lord, it was in their best interest to have a backdoor, in case of emergencies. These are known as postern gates or sally ports. They are small, hidden entrances into the castle complex that are away from the main gate and just big enough for one man on horseback to go through at a time. These gates were built in a place where they could not be attacked or destroyed by enemy artillery. 

In the event of a siege, people could still come and go relatively unnoticed. This allowed for food and other resources to be brought in, send messengers out, or even flee the castle if it came to it. They were also used to launch small raids on the besiegers by attacking isolated pockets of enemy forces, sabotaging siege equipment, or destroying their food supplies. Since most castles had at least one, postern gates were not really a secret but were generally hard to find.  

What was secret, however, were hidden passages that some castles had. One such example of a secret passageway is at Bran Castle in Romania. It connected the first and third floors of the castle and was used in the event of an emergency. It was so secret, in fact, that it was only rediscovered in 1920 during some extensive renovations.