Buzz
We don’t often think much about the behinds of our animal relatives, but it’s time to pay attention because some of them feature bizarre yet surprisingly practical backsides! While our own serves mostly for sitting (though that's debatable), many creatures have shaped their rears for various purposes – from defensive mechanisms to romantic signals. Here are 10 of the most remarkable and revolting animal butts that have fascinating roles.
10. Baboons
Do you remember your first visit to the zoo and wondering why the baboon’s behind seemed so unusually odd compared to... well, all the other animals? Though it may look strange, the baboon’s rear end has evolved for a very particular reason: when females are ready for mating, their rears swell to impressive sizes as a signal of sexual receptiveness.
This has turned into a kind of rivalry, where the females in a group essentially compete for the males' attention. The males are drawn to the females with the largest, most prominent rears. The process of expanding their backside is energy-consuming, as it significantly adds to their body weight—sometimes by as much as 14 percent.
When a female is ready to mate, typically every 37 days, she will present her rear to the male suitors. Baboons are known for their promiscuity, mating with several males during their 'courtship' phase. Interestingly, the size and color of a female’s backside don’t always indicate her fertility. Studies show that although males are attracted to the vivid red rumps, they generally prefer females who have had more ovulation cycles or who have had some time since their last litter.
9. Wombats
The wombat is an intriguing creature from Australia. It holds the distinction of being the largest mammal that lives underground, and this fascinating behavior is linked to its rear end! The wombat has developed an exceptionally tough backside filled with cartilage, essentially creating an 'armored rear.' This resilient posterior allows it to block its burrow, protecting itself from predators.
Wombats may not be the fastest animals, so they rely on their sturdy backside to protect themselves and their young. You may wonder if their exposed rear could pose a risk, considering it’s tougher than the rest of their body. However, there’s no need to worry—this creature’s tail is only 2 centimeters (1 inch) long.
While the wombat’s rear is mainly used for defense, it also serves as a potent weapon. When cornered in its burrow, the wombat can use its backside to slam the skull of its attacker against the burrow walls or roof. This defense tactic works on predators like the Tasmanian devil and dingoes.
8. Skipper Caterpillars
When most people think of caterpillars, they usually picture the more graceful butterflies. However, the skipper caterpillar may make you do a double-take... or quickly look away due to its unique defensive feature called scat firing. For those unfamiliar with the term, 'scat' is a polite way to refer to animal poop.
When faced with danger, the skipper caterpillar launches its feces as a defense mechanism, deterring potential predators like birds or even unsuspecting humans. Not only can it hurl its poop away from itself, but it can project it a remarkable distance—up to 40 times its body length at speeds of 1.3 meters per second (4.3 ft/sec). For a 6-foot human, that’s roughly the equivalent of 75 meters (240 feet).
This fascinating behavior is not just a remarkable feat of evolutionary adaptation but also an impressive mechanism in action. The caterpillar’s poop is stored as small pellets beneath a specialized anal 'launching pad.' By increasing blood pressure below this area, it can propel the feces, much like a catapult hurls a boulder.
For a long time, scientists believed that this poop-flinging behavior was merely for cleanliness. It helped keep the caterpillar's home free of waste while the caterpillar itself went about its carefree existence, munching on leaves and transforming into a rather unique butterfly.
However, it turns out that flicking poop is an incredibly effective strategy for keeping the caterpillar's main predator, the paper wasp, at bay. The wasps are drawn to the scent of the feces, which suggests that the caterpillar’s real reason for maintaining a tidy home is to mask the smell of its own waste and avoid detection.
7. Pygmy Sperm Whales
Two terms you definitely don’t want to hear while swimming near a pygmy sperm whale are 'defense mechanism' and 'anal syrup.' Honestly, the combination of 'anal' and 'syrup' doesn’t exactly paint a pleasant picture.
The pygmy sperm whale is exactly what it sounds like – a smaller version of the sperm whale. While most whales rely on their massive size to deter predators, the pygmy sperm whale opted for a different strategy, growing to only around meters (11 feet).
To defend itself, the pygmy sperm whale developed a unique defense—a bladder at the end of its intestines containing roughly 11 liters (3 gallons) of 'anal syrup.' When threatened, it violently ejects this reddish-brown goo, using its tail to create a swirling cloud of the noxious substance.
Unsurprisingly, this cloud of goo works wonders in deterring predators and helps the whale make its escape. It's a defense mechanism similar to the ink sprays used by octopuses and squids, though it’s unique to this specific type of whale.
6. Dragonfly Nymphs
The dragonfly’s early life begins underwater as a nymph, not unlike a mosquito larva. However, unlike its blood-sucking relative, the dragonfly has a unique adaptation in its rear end.
To propel itself through the water, the dragonfly nymph ejects a jet of water from its anus, shooting itself forward. It also breathes through this same opening, using specially designed gills inside. As fascinating as this is, the most remarkable thing about the dragonfly is that it cannot feed without its butt! Its labium, or mouth-grabber, is activated hydraulically.
Once the dragonfly takes in water through its rear, it clenches its muscles, compressing its abdominal and thoracic areas against the water-filled rectal chamber. This creates pressure in the body, which then forces the dragonfly’s jaws to shoot out at incredible speeds with up to one pound of pressure. This may not sound like much, but for a creature only 1–3 centimeters (0.5–1.5 inches) long, it’s quite a feat.
5. Manatees
At first glance, the manatee’s anus might appear perfectly ordinary, but beneath its seemingly normal exterior lies a fascinating secret. Known as the sea cow, this charming marine mammal has one of the most muscular and unusual diaphragms of any mammal, an adaptation that helps it manage buoyancy by holding and releasing gas.
In essence, the manatee expels a considerable amount of trapped gas from its body to control its buoyancy, allowing it to dive deeper or float to the surface. This is similar to how we swim deeper by exhaling air from our lungs, except the manatee releases its air through its rear end.
This method is uniquely suited to the manatee, as most marine mammals use collapsible lungs and blowholes to adjust their buoyancy and manage changes in pressure. The manatee, however, took a different approach and opted to navigate the world’s rivers and oceans with the help of its own flatulent propulsion.
If you’re interested, the internet is full of videos showcasing this exact phenomenon. To witness and hear a manatee fart for yourself, just check out the video linked above.
4. Sea Cucumbers
Although most people would never associate a sea cucumber with aggressive behavior or a particularly noteworthy anus, these creatures possess a fascinating defense mechanism. Sea cucumbers have developed an impressive way to protect themselves from potential threats.
Sea cucumbers possess the incredible ability to expel their internal organs through their anuses, a tactic used to entangle and repel predators. This highly unusual and rather repulsive defense mechanism is made even more astonishing by the fact that some of these ejected organs are toxic. They contain a substance called holothurin, which can be lethal to various species of fish.
This remarkable process, known as evisceration, involves the expulsion of internal organs, or disembowelment. You might be wondering, "Doesn't the sea cucumber need its organs?" The answer is surprisingly yes! These fascinating creatures can regenerate nearly any internal organ they eject in a mere 6 to 10 weeks.
3. Ravine Trapdoor Spiders
Few creatures have evolved such a highly effective rear end as the trapdoor spider. Most of these spiders catch prey by digging a small hole with a trapdoor they can quickly hide under. When an unsuspecting victim passes by, the spider strikes from its burrow to catch its meal. Some species within the Cyclocosmia genus have evolved even further and no longer require a hinged trapdoor at all.
In a clever defensive move, the trapdoor spider uses its rear to seal the entrance to its burrow. This rear end is not only specialized for this task but is a tough, disk-shaped structure reinforced by ribs and grooves. It helps the spider keep its home looking unthreatening to any prey that may wander by.
The spider uses this unique, hardened disk as a plug whenever it feels endangered, meaning that in the wild, the most visible part of this spider is its remarkable abdomen. This feature likely evolved as a defense mechanism against predatory wasps, which would otherwise be able to sting and drag the spider out of its safe burrow.
2. Fitzroy River Turtles
While most turtles breathe through their nostrils, the Australian Fitzroy River turtle has developed the rather unusual ability to breathe through its anus. The natural reaction to this discovery might simply be: 'Why on earth?'
There’s actually a very practical reason why this little, protected turtle has evolved to ‘breathe out of its butt.’ This unique trait allows the turtle to stay submerged underwater much longer than its relatives, reducing its chances of becoming prey and improving its ability to forage for food.
The Fitzroy River turtle possesses a specially designed cloaca (similar to an anus) that enables it to absorb oxygen directly from the water. This adaptation allows it to extract as much as 41 percent of the oxygen it needs from the water, which can be stored and used later, allowing the turtle to remain underwater for up to three weeks without needing to surface for air like other turtles.
Thanks to this incredible feature, the Fitzroy River turtle has earned the nickname ‘bum breather.’ Other turtles have cloacae that can absorb small amounts of oxygen from the water, but their absorption rates rarely exceed 4 percent, which makes the Fitzroy River turtle truly one-of-a-kind.
1. Chinese Yellow Swallowtails (Butterflies)
Most people would likely agree that having the ability to ‘see’ on one’s rear end isn’t exactly ideal. The Chinese yellow swallowtail, however, didn’t get that memo and has developed two intriguing photoreceptors right at the tip of its backside.
While these aren’t eyes in the conventional sense, these photoreceptors are capable of detecting light and identifying various stimuli to assist the butterfly in mating and egg-laying. This light detection process is known as chromatic contrast.
One of the primary functions of this unusual ability is to help the male and female butterflies align their genitalia during copulation. Apparently, it was a bit tricky at first, so the butterflies evolved these rudimentary ‘eyes’ to solve this problem.
The reason behind this odd adaptation lies in the butterflies’ mating environment. Since they only mate in sunlight, the photoreceptors on their rear ends allow them to detect contrast shifts, especially in the blue color spectrum, helping them distinguish mates from other objects. This enables precise genital alignment… and, well, you can guess the rest.
+ Giraffes
While giraffes don’t necessarily have an evolutionary trait that makes their rear ends exceptionally useful, they’ve found an unexpected purpose for them. Giraffes will twist their bodies into a seemingly uncomfortable position and use their backsides as pillows, which just might explain why they evolved such long necks. (I bet you thought it was just to munch on leaves from tall trees!)
Giraffes' sleep habits are quite fascinating. Not only do they rest their heads on the very same area they use for defecating, but they also sleep less than any other mammal. Giraffes are known to require only about 30 minutes of sleep within a full 24-hour cycle.
They manage this by taking several brief, intense naps lasting around five minutes each. This strategy is thought to be a defense mechanism, allowing them to stay alert and reduce the risk of being preyed upon, as they are always on the move instead of resting for hours like most mammals tend to do.
