Evolution works in mysterious ways — and while natural selection has allowed some species to
develop into the best versions of themselves, it has also led others down some very strange
paths indeed. These are the worst animal evolutions in the world of natural history.
"Royalty of the cat family" sounds like an honor that should belong to the lion, given its regal
reputation. However, the title actually fits the cheetah better… but not for a good reason.
Today's cheetahs are an incredibly inbred species, making them extremely susceptible
to fatal feline diseases. Based on scientific analysis, all surviving cheetahs may have come
from a handful of post-Pleistocene ancestors. At some point within the last 10,000 years,
they may have experienced a sharp population reduction, which drastically reduced their
genetic diversity. And while cheetahs used to enjoy wide land distribution,
they are now mostly limited to certain areas of eastern and southern Africa.
Being the fastest land animal may make the cheetah's life seem like a cakewalk,
but that's not really the case. For starters, the cheetah hunts during the daytime,
relying on eyesight rather than smell to stalk its prey. If the chase takes too long,
the cheetah stops; its speed strains the cat's body and spikes its temperature,
requiring it to take a long recovery period after difficult pursuits. Furthermore,
the cheetah's bite alone isn't enough to kill gazelle or antelope — it has to chase its target,
trip it, and then bite its throat to either suffocate it or puncture an artery. And it has to
eat fast, too, as even a single hyena can steal a cheetah's hard-earned lunch. Speaking of...
Spotted hyenas are perhaps best known for their strange vocalizations,
which sound a lot like laughter to human ears.
In reality, these sounds make up a complex system of communication
and — depending on intensity and pitch — can mean anything from a warning to a call for help.
However, there's another thing that spotted hyenas are famous for, and it's hardly a laughing matter:
their difficult and dangerous way of giving birth.
Female spotted hyenas are larger, heavier, and more aggressive than males of the species.
This explains why spotted hyena clans have a single matriarch in charge,
and why females always outrank males in these groups. Interestingly, female spotted hyenas'
genitals closely resemble penises, making them the only mammalian females to copulate,
urinate, and give birth through the same canal. Yeah, you heard that right: Hyena
cubs pop out from these pseudo-penises, and yes, it's exactly as painful and brutal as it sounds.
In fact, a female spotted hyena's birth canal has a diameter of only one
inch. It's also not uncommon for hyena cubs to suffocate on their way out,
and it's said that only two in every five cubs survive this process. And it's not
just the babies, either: first-time mother mortality rates are very high in hyenas, too.
A cursory examination of a giant panda's daily routine makes it seem like quite a lazy creature.
After all, it spends more than half of its waking hours foraging and eating,
while the remaining time is reserved for rest and recreation. Unfortunately,
a closer look at the panda's digestive system reveals that its life is far from ideal.
Despite being classified as a meat-eater, the average panda consumes 20 to 40 pounds of bamboo
daily. But bamboo isn't the most efficient choice for it, diet-wise. As the panda doesn't have the
necessary type of gut bacteria to break down the bamboo properly, it doesn't really get as many
nutrients from its hefty meal as you'd expect, and around 83% of what it eats comes straight
out the other end. Oddly enough, the panda's teeth, jaws, and wrists evolved over millions
of years to be better suited for their peculiar dietary preferences. Furthermore, pandas' taste
buds are extra adept at detecting bitter tastes too, which can often signify toxins in plants.
Unfortunately, pandas aren't as talented when it comes to a different aspect of survival:
reproduction. Female pandas can only conceive once a year, and males aren't particularly
good at doing the deed either. Perhaps unsurprisingly, conservationists sometimes
have no choice but to resort to artificial insemination, just keep the species going.
Present-day sloths are a far cry from their gigantic ancestors. Roughly the size of a dog,
these fur-covered mammals are among the slowest-moving animals known to man. In fact,
they move so slowly that blue-green algae grows on them. While this helps them hide from predators,
the presence of algae also makes the sloth's fur a suitable habitat for all sorts of insects
and parasites. And their lethargic behavior matches their metabolism, which only performs
at 40% to 45% of what their weight would normally require. Scientists still aren't sure exactly how
slow a sloth's digestive system works, but the estimated timeframe is astounding: it
takes anywhere from six and a half days to nearly two months for a sloth to digest a single meal.
Interestingly, sloths are pretty good at swimming. Considering they spend
nearly all of their time out of the water, however, it seems likely that
they have evolved this ability to help them when they accidentally fall out of trees.
Koalas are part of a very small circle of animals known to man who are capable
of surviving a diet of eucalyptus leaves. While it's certainly an impressive feat,
this marsupial also has some strange traits that aren't quite as awesome.
For example, koalas are "smooth-brained," meaning their cognitive skills aren't as
sharp as most animals. Indeed, they are reportedly unable to recognize eucalyptus
leaves — literally the only thing they eat — even when they're lumped together on a plate.
You might even wonder why koalas bother eating eucalyptus leaves in the first
place as they're incredibly tough, highly toxic, and lacking in nutrients. Worse still,
over time, koalas grind down their teeth trying to chew the leaves, and when they're totally gone,
the koala just dies of starvation. Still, a koala's digestive system is designed to
handle the leaves' toxicity and they can even tell which types of eucalyptus are too
poisonous to eat. However, since eucalyptus leaves aren't exactly great sources of energy,
koalas move slowly, and are typically awake for only four hours a day.
Experts believe that having a colossal pincer helps fiddler crabs win fights
and appear to be more viable mates. But this unique characteristic causes more
problems than it solves. As University of Texas researcher Dr. Zachary Darnell tells Gizmodo:
"The large claw is metabolically costly, it hinders feeding because it is cumbersome for
this task, and it reduces endurance capacity when crawling on the sand. Male crabs are both
heat-stressed and hungry while on the surface, foraging and performing the claw-waving display."
Interestingly, Darnell added that the bigger claw functions as the crab's thermoregulator,
as its body heat travels to its major claw and dissipates into the air.
And while having a disproportionately massive claw can be both a bane and a boon for the crab,
being dishonest about it can land the crustacean in serious trouble.
A fiddler crab replaces its lost major claw with a flimsier, toothless claw that's nowhere near
as strong. The crab is then able to bluff its way out of fights by looking like it's
capable of delivering a beatdown — unless a rival male actually challenges it, that is.
"Come on." "Come on." "Come on." "Come on." "Let's go." "Come on."
With its surprising degree of intelligence,
excellent camouflage skills, and regenerative abilities, the octopus seems exactly like the
sort of animal that would take over the planet if humans were to one day suddenly disappear.
Unfortunately, they're simply not built for world domination — literally or figuratively.
Firstly, octopuses don't live very long; the lifespan of the average octopus can be
placed somewhere between six months and a few years. Additionally, despite their impressive
cognitive abilities, their lack of protective covering makes them easy targets for predators.
Furthermore, the reproductive process straight-up sucks for both male and female octopuses.
Different types of octopuses disperse their sperm via a specialized arm called a hectocotylus.
This arm plugs into their mate's mantle cavity, and in some cases, they end up losing it.
It's all downhill from there, too, as the male octopus either expires some time after mating,
and in rarer cases, it is even strangled and eaten by its mate. And females don't have
it much easier, as they lay large clusters of eggs… before giving up eating entirely.
Horses are incredibly useful creatures. They have a long history of providing strong and reliable
steeds for humans, whether for travel, athletic, or recreational purposes. Sadly, there's abundant
evidence suggesting that horses actually got the short end of the evolutionary stick.
To start, horses have highly specialized breathing systems to accommodate their respiratory needs.
But this means that horses are obligate nose-breathers, as they can't use their
mouths to take in oxygen. Thus, any obstruction in their nose can easily kill them. Furthermore,
an overworked horse can suffer from exertional rhabdomyolysis, which can cause muscle pain,
muscle necrosis, and eventual kidney damage. Horses don't have the ability to vomit, either,
and the ability to throw up is crucial for animals to expel ingested poisons from their bodies.
Moreover, given a horse can weigh up to 2,000 pounds, a simple leg injury can be
lethal. As veterinarian Jenny Hall explained to The Guardian:
"[A horse's leg bones are] very strong [...] yet they're light,
for them to be able to go fast. So, unfortunately, sometimes, when they break, they just shatter."
And because there's very little soft tissue around the horse's leg bone, a fracture
almost always punctures the skin, damaging its nerves and blood vessels and causing tissue death.
In most cases, horses that suffer from leg injuries have to be put down.
In the forested areas of North America and Canada lives the luna moth — a lime-winged creature whose
only purpose in life is to reproduce. Of course, you might think that individuals of the species
have to live long and receive enough nourishment to procreate with gusto. But not quite:
As it turns out, adult luna moths only have about a week to fulfill their life's mission,
meaning they have no time for silly things like "eating" or "having a digestive system."
Adult luna moths sport white bodies and pink legs and can have wingspans of up to 4.13 inches.
Moreover, a luna moth's mouthparts are vestigial — in other words, they're useless. Instead, the moth
relies on the baby fat it had as a caterpillar to give it energy. From the moment its pupal stage
ends, the luna moth pumps a blood-like substance called hemolymph to its wings to enable it to fly.
Indeed, a male luna moth can travel impressive distances to find its mate, with the mating ritual
taking place a few hours past midnight. A female luna moth lays around 200 eggs on a suitable leaf,
which will hatch after a week and a half, starting the cycle all over again. Hey, it's a living.
Judging from looks alone, it may be hard to believe that a bird as small as the kiwi
has some pretty huge cousins. It's true, though: kiwis are ratites, a diverse group of flightless
birds that may have been around since the late Cretaceous period. Scientists aren't completely
sure how kiwis came to be New Zealand natives, but the country's Department of Conservation
lists five different species of the bird, which has come to be embraced as its symbol.
"I love New Zealand! That's great,
that's good information to find out! Lord of the Rings… Frodo…"
Oddly enough, kiwis have traits that are more mammalian than bird-like. For example, the kiwi
has a lower body temperature than most birds, with strong, heavy, marrow-filled legs accounting
for a third of its body weight. Moreover, female kiwis have two functional ovaries,
unlike most avians, which have just one. Kiwis' eggs are also about six times larger
than expected for a bird of its size. In fact, the pressure a kiwi egg exerts on its mother's
organs is so great it can eventually make eating impossible for the parent until it lays that egg.
Unfortunately, the kiwi's size and flightlessness make it an easy target for mammalian predators —
particularly non-native ones. Worse still, recent studies have shown that some kiwis may be evolving
into blindness, since their nocturnal lifestyles make actual vision a waste of energy.
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