There were all kinds of teeny-tiny animals skittering
and slithering around our planet.
But have you ever stopped and wondered what actually is
the smallest animal on Earth?
Let's find out on today's episode of Colossal Questions.
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In order to answer this question,
we first need to decide on an answer
for a much more basic question.
What actually is an animal?
Seems simple, right?
Well, as it turns out, the answer
actually gets a bit murky.
Scientifically speaking, an animal
is any living organism that's made up of multiple cells,
eats organic material, breathes oxygen, can move,
and can reproduce.
Humans fit the bill.
We're made up of trillions of different cells.
But there are lots of things out there so small
that they're made up of just a few cells clumped together.
There are some living things out there
that are made up of just one single cell, like bacteria.
Well, that means they're not considered animals
but prokaryotes instead.
That's just a fancy science way of saying
they're a super basic, single-celled organism.
In fact, their cell doesn't even have a nucleus,
which is what controls a cell.
More complex cells, like animal cells, have a nucleus.
Inside that nucleus is all the DNA
that helps make us into something much more complex
than a single cell.
These types of organisms are called eukaryotes.
Almost all living organisms you can see on Earth
are eukaryotes, including plants, and, yes, all animals.
In 2011, the smallest known animal was discovered,
a jellyfish called a Myxobolus.
They can be really small, like less than 9 micrometers long.
That's around 1/1000 of an inch.
Really tiny.
Of course, this is just the smallest animal
we currently know about.
New discoveries are made all the time.
So who knows?
Before long there could be an even smaller critter
crawling around somewhere.
OK, so this little jellyfish might technically
be the smallest animal we know about today.
But it does beg the question, what's
the smallest known animal you can actually
see with the human eye?
The answer to that question is found
on the second largest island in the world, New Guinea.
That's where scientists back in 2009
discovered the smallest known vertebrate in the world hopping
around the jungle, a tiny little frog
called Paedophryne amauensis.
The average adult only grows to be about 8 millimeters long
from end to end, which is only slightly bigger than the eraser
on the back of your pencil.
Then there you have it, a seemingly simple question
with a surprisingly complex answer.
So for now those microscopic little jellyfish
will remain the smallest animal on Earth.
And our little frog friend will continue
to be the world's smallest known vertebrate, that is,
until we find something smaller, of course.
Over eons of time, there have been tons of titanic creatures
who have walked the Earth, soared through the sky,
and swam in the oceans.
But have you ever stopped and wondered
what actually is the largest animal to ever exist?
Let's find out on today's episode of Colossal Questions.
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Many of the biggest animals to ever exist
live hundreds of thousands or even millions of years ago.
Take Gigantopithecus, for example.
The largest ape to ever live was a distant relative
of modern day orangutans, who stood somewhere
between 8 and 10 feet tall.
That's mighty big to us humans.
But it pales in comparison to the biggest animals ever.
The largest creature living on land today
is the African elephant, which can weigh up
to 7 tons, which is about the same as your average delivery
truck.
A full grown African elephant can
be up to 35 feet from trunk to tail
and stand about 12 feet tall.
OK, that's the largest land animal on Earth today.
But what's the biggest animal ever?
Well, believe it or not, it's not
a dinosaur or a woolly mammoth or any kind
of colossal creature from the past.
That's right.
It turns out the largest animal ever is actually living today.
But it doesn't live on land.
It thrives deep in the ocean, quietly bigger
than any massive meat eater who ever lived.
It's the blue whale.
And it's not even that close.
Blue whales can be anywhere between 75 and 100 feet
long when they're fully grown and can weigh well
over 100 tons.
To put that into perspective, that's
about as long as three school buses lined up and heavier
than a space shuttle.
Their heart is about the size of a small car.
And their arteries are big enough for a human
to actually climb through.
They're so big that a group of 50 people
can stand together on a blue whale's tongue.
Even baby blue whales are big.
A newborn calf is about 25 feet long
and already weighs more than an African elephant.
This makes blue whales not just the biggest creature on Earth
but the biggest by a wide margin.
You might imagine that the mighty dinosaurs who
lived millions of years ago were bigger.
But, nope, maybe the largest known dinosaur
is the Argentinosaurus, which only
weighed around 180,000 pounds or about half the weight
of a blue whale.
It might seem surprising to us.
But it actually makes a lot of sense
that the world's biggest creatures live underwater
rather than on land.
Land animals have to be able to support all that weight.
But sea creatures get some extra help
from the water, which makes it easier
to grow nice and, well, colossal!
There's plenty of creatures on Earth
that can do all kinds of damage.
But who is the most dangerous of them all?
Let's find out on today's episode of Colossal Questions.
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We have lots of good candidates for deadliest animal on Earth.
Take elephants for example.
They're the largest land animals on Earth
and can be fiercely aggressive when provoked.
They have no problem dribbling people or other animals
or even entire villages when they're angry.
And if that wasn't destructive enough,
elephants also have excellent memories,
which means they might even hold a grudge if they're really
wronged.
Hippos are another of Earth's most aggressive animals.
Even though they mostly eat plants,
hippos are huge and more than willing to fight even
for no reason at all.
And yet, the deadliest animal of them all
is also one of the smallest--
mosquitoes.
These bothersome little bugs are so deadly because they
can spread viruses from person to person
when they suck your blood.
Expert's report that nearly 700 million people each year
get a disease from a mosquito bite, which
leads to somewhere between two and three million deaths.
Malaria, dengue, and Zika are three
of the many diseases that you can get from mosquito bites
if you live in high-risk areas.
But before you start building a bunker to hide in,
there is some good news.
Since the year 2000, medical advancements
have led to an almost 40% drop in malaria deaths.
And unless you live in certain areas,
there's no real risk of getting a deadly disease.
So next time you're on a safari, just keep a safe distance
from the elephants and hippos.
And definitely wear bug spray.
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Every year more and more animals are in serious danger
of going extinct.
But have you ever stopped and wondered,
what causes animals to go extinct in the first place?
Let's find out on today's episode of Colossal Questions.
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Of all the animals that have ever lived on Earth,
99.9% are now extinct.
The first and most common way that animals go extinct
is what we're going to call extinction by natural causes.
This is when a species dies out naturally because of forces
like climate change, competition from other animals,
a reduced food supply, or most likely a combination
of all three.
Most natural extinctions happen very slowly, over hundreds
or even thousands of years.
But every once in a while, a catastrophic event
can lead to a quick mass extinction,
like the meteorite that killed the dinosaurs.
Natural causes may have been the main reason
animals went extinct throughout most of Earth's history.
But over the last couple hundred years,
humans have given nature a run for its money
as the biggest cause of extinction.
That's right.
Over the last 500 years or so, humans
have hunted lots of animals into extinction.
Take the passenger pigeon, for example.
When European settlers first arrived in North America
in the late 1800s, there were 3 billion to 5 billion passenger
pigeons living there.
By the 1800s, hunting and eating the poor pigeons
was so widespread in US that the very last passenger
pigeon died in 1914.
And that's just one example.
Some species, like the American bison, are luckier.
Millions of bison lived in North America
until the Europeans arrived.
Hunting was so intense that only 541 were left by 1889.
Sound familiar?
Well, unlike the passenger pigeon,
this story has a happier ending.
A handful of ranchers gathered the remaining bison together
to save them from extinction.
Since then their numbers have flourished.
And more than 300,000 bison live today
on farms and national parks around the US and Canada.
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Animals are also hunted for body parts like fur, feathers,
hides, or horns.
And hunting isn't the only way humans
cause animals to go extinct.
Habitat loss is a huge problem too.
When we build giant farms to grow food,
the natural land that many animals rely on
is destroyed, leading to their extinction.
Pollution can poison the land, air, and especially water
and has at least 700 marine species on the brink
of extinction right now.
So just remember, like tigers, elephants, and rhinos,
even the mightiest animals are at risk of extinction
if we're not careful.
Have you ever stopped to watch two animals interact
with each other and wonder, can animals actually
talk to each other?
Let's find out on today's episode of Colossal Questions.
Experts say that all languages from cultures
all around the world are rooted in turn taking.
One person talks.
Then the other responds back and forth.
We just call that, well, talking.
And it might seem basic.
But it forms the foundation of all languages.
And believe it or not, most animals across the globe
tend to turn take with each other too.
There's still lots of research that
needs to be done on how animals talk to each other.
But experts are confident that animals definitely can
communicate with each other.
In fact, anyone who spent time around a pet probably already
knows this.
Dogs and cats respond to commands or even specific words
that they can understand.
They can also talk back to you.
Most pet owners can tell when their dog is hungry or tired
or needs to pee or wants to play.
All of that is your pet talking to you.
All the different sounds that animals make
are a form of language-- barks, meows, croaks, bleats, tweets,
roars, and songs are all ways for those animals
to communicate.
According to experts, prairie dogs
have one of the best vocabularies of any animal
out there.
They don't just use words or sounds
to tell other prairie dogs that there's a looming threat.
They can also use more expressive words that
let the others know the size, shape, threat level,
and oncoming speed of an approaching creature.
In most cases, experts are still trying
to understand what animals are saying to each other.
But it's pretty clear that animals everywhere
are always talking.
So do animals talk to each other?
Absolutely.
It just might be a while before we have any good idea what
they're saying.
[barking]
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Ah, huh, what?
Oh, sorry, guys.
I was having a dream about my dog.
Speaking of dreams, have you ever
stopped and wondered what's going on in your furry friend's
head while it sleeps?
Do animals have dreams the same way humans do?
Let's find out on today's episode of Colossal Questions.
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The hardest part about answering this question for scientists
is that, well, pets can't tell us about their dreams.
But, basically, everything we do know about whether or not
animals dream comes from what we know about our own dreams.
Each night about an hour or two after you fall asleep,
your eyeballs will start darting around
behind your closed eyelids.
This stage of your sleep cycle is
called REM or REM sleep, which stands for rapid eye movement.
During this stage, your body is powered down.
But your brain is as active as when you're awake.
For humans, the REM stages when dreaming begins.
Many scientists have looked at the brain activity
of sleeping animals to try and solve the mystery once
and for all.
What they found is that almost all mammals and birds have
a REM stage when they sleep.
And cold blooded animals, like reptiles, amphibians, and fish,
don't.
But the research didn't stop there.
Researchers at MIT put rats on a track
and measured their brain activity
while they move towards food at the other end of the track.
Once the same rats fell into the REM stage of sleep,
they measured their brain again and saw identical patterns.
This led scientists to believe that the rats were
dreaming about running for food on the track.
Many experts believe the same thing is true for dogs.
Like rats, pups likely dream about their day
to day lives and experiences.
Pretty cool.
Even cooler, the smaller the dog, the more it dreams.
Small dogs can have dreams as often as every 10 minutes,
while bull dogs can have an hour or two between dreams.
In another study, scientists measured the brain activity
of singing birds.
Once the birds fell asleep, the researchers measured again.
And you guessed it, the brain activity
was almost exactly the same.
The experts still don't know for sure.
But this has led many to believe that the birds are either
dreaming about singing or they can hear their own song
in their sleep.
So does your little pug muffin dream?
Many experts think it's likely.
So next time your dog starts running in place
while it's sleeping, rest assured
she's probably dreaming about that great, fuzzy tennis
ball in the sky.
That's a good boy, Mr. Sprinkles.
[barks]
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