Hi, I'm Danielle Dufault,
and you're watching "Animalogic: Second Nature."
[man] Ah!
[Bat screeching]
[Danielle] What is it like to be a bat?
They roam the night when it's pitch black.
Their prey is small, fast, and well camouflaged.
It seems like a losing battle,
but the bat has another card under its wing.
It can see the echo of its own voice.
It's the most advanced sensory tool in nature,
and it's evolved separately in several different species.
This is echolocation.
[Dolphin clicking]
I was just conducting a little experiment,
trying to find out how the devil bat does its killing.
[♪♪♪]
Some animals have built-in
military-grade machinery in their heads.
A biological sonar system.
The animal will make a high-pitched noise
and hear the echo,
allowing them to map the world around them.
When the sounds bounce off of different materials,
they sound different.
And the closer the object is,
the faster the sound will bounce.
This is an amazing strategy, but it has a big drawback.
As the high-pitched noise travels
and disperses through the air, it loses power density.
Some of the sound is also absorbed by the air and water.
But to deal with this, they have two adaptations.
They can make extremely loud noises that can travel far
and they have amazingly sensitive hearing.
The best natural sonar
belongs to bats who use it to catch prey as small as a moth.
There are over 1200 species,
and over half of these spooky creatures echolocate.
You've heard about the bats they have here.
Some of them bats is rabid!
Well!
[Danielle] Different species use different frequencies,
and they range from about 20 to 200 kilohertz.
Lower frequencies travel further,
but higher frequencies paint the best 3-D picture
of their surroundings,
especially when they chirp 200 times a second.
[Bat screeching]
Look out!
[Danielle] Luckily, their sonar is outside our range of hearing.
Their clicks can be as loud as a chainsaw.
And if we were able to hear
thousands of flying chainsaws at night,
we'd never sleep again.
The clicks go out extremely loud,
but by the time they come back
they can be thousands of times quieter.
To detect them, they need super hearing.
Their inner ear has a very high concentration of receptor cells.
In some species,
they can tell the differences in sound as slight as 0.1 hertz.
To prevent their chainsaw-loud chirps
from destroying their sensitive ears,
they physically unplug their ears.
They can contract muscles in their head
to detach the inner ear bones from each other.
The most amazing thing about it
is they can chirp for a few milliseconds,
then plug their ears back for a few seconds
and repeat the process over 200 times a second.
Ah, my friend, how your theory of glandular stimulation
through electrical impulses was correct.
Another low visibility environment
where echolocation is helpful is the ocean,
and the best echolocators are the toothed cetaceans,
like dolphins.
[male announcer] Nobody ever trained a porpoise,
but judging by their ability to stand on their tails,
they have possibilities.
[Danielle] Dolphins are amazing explorers, hunters,
and social creatures
despite not being able to rely on their sight
or their sense of smell to navigate their environment.
And they manage to do it all through echolocation.
[male announcer] It's plain to see why saltwater fisherman
hate to see porpoises appear.
They can ruin fishing.
[Danielle] To make their clicking noise,
they slap structures in their blowholes called "sonic lips."
[Dolphin clicking]
[Danielle] They have two pairs of lips
as they evolved from the two nostrils
in their terrestrial ancestors,
so they can make two clicks simultaneously.
The sound then travels through the melon,
the fatty part of the dolphin's head,
which can change its shape to focus the soundwave
to the object of the dolphin's attention.
It's basically a lens for sound.
The echoes are then received through the dolphin's lower jaw
and transmitted to the inner ear,
and all of this happens in a fraction of a second
as sound travels faster in water than in the air.
Now, since the watch is waterproof...
[Ticking]
I guess that proves that sound
also travels better through water.
That's right.
Rehabilitated dolphins
at the dolphin research centre in Florida
are teaching scientists about their ability
to see through their ears.
Blindfolded dolphins are able to find a metal ring
at the bottom of a pool
by sensing the differences in the echoes
that bounce of the ring and those that bounce off the sand.
A helpful tool when you're looking for your keys
before leaving the house.
[Whistle blowing]
[Dolphin chirping]
Yay!
[Danielle] This other dolphin can copy his friend's actions
just by hearing them.
Their ears are really high precision tools.
[Dolphin chirping]
[Whistle blowing]
[Danielle] Fortunately for beachgoers and scuba drivers,
we can't hear the clicks
as they're emitted at over 100 kilohertz
in order to avoid being heard by killer whales.
Toothed cetaceans are not the only mammals who echolocate.
Over 100 species of shrews and several other small animals
have developed the ability to use sound for navigation.
Have you ever heard of a shrew?
No, the animal.
Radford called them "sorex soricidae"
when he showed you one.
Well, then "shrew" must be the common name
Cute?
That's the last word you can use to describe
those little monsters.
They're the most horrible animals
on the face of the earth.
[Danielle] Shrews, for example,
are very vocal animals and are known to twitter
when exploring new environments.
Like bats, shrews are nocturnal animals,
but since they're close to the ground,
they're able to use their sense of smell to find food.
Do you believe in fairy tales?
Well, I'm a little old for that sort of thing,
but what did you have in mind?
There are 2- or 300 giant shrews out there.
Monsters weighing between 50 and 100 lbs.
[man] That's as big as a full-grown wolf.
And what's more, they're beginning to starve.
[Danielle] In both bats and dolphins,
there was a need to develop a high frequency echolocation
to avoid attracting predators.
But shrews' tweets might not be loud enough to attract predators
and are even in the range of human hearing.
Their echolocation is very rudimentary,
and it's mostly used as a complementary tool
to determine soil density and to sense big obstacles,
like logs and rocks.
[Gunshot]
.
The shrews were out there! I couldn't take a chance!
The most unlikely animals to echolocate are birds.
Only a handful of genera are known to do this and among them
the oil bird is the king of the sonar.
Oil birds should be called "bat birds."
They only have their current name due to the fact
that their babies are so fat
that they can be used as fuel for oil lamps.
But their behaviour is surprisingly bat-like.
Their huge colonies roost in caves as high as possible.
They're fully nocturnal, and of course, they echolocate.
Unlike the other animals in this episode,
they only eat fruit and have amazing nocturnal vision
which suggests they don't need to echolocate to find food.
The majority of their echolocation
happens in their caves
as a way to navigate their pitch-black homes
and possibly to communicate with each other
in one of the greatest cave cacophonies on earth.
Despite this, there's evidence to suggest that echolocation
has evolved separately multiple times in birds.
With a little luck,
we might see new birds develop this amazing sense.
[Loon clicking]
[Danielle] If you watch the channel regularly,
you may have noticed that I've been wearing
my new Animalogic watch.
It was made by Undone Watches, today's episode sponsor.
Undone Watches is one of our best friends and supporters.
They've designed several watches based on the art of the show
and given some away to fans from all over the world.
The watches are awesome.
I wear mine every day.
If you like them, you have one more chance to win one.
The last two contests were such a success that Undone is back
with a brand-new design.
And they want to give you a chance to win one of them.
The new watch is absolutely stunning.
I can't wait to get my hands on one.
Click the link in the description
to enter for a chance to win
one of these amazing time pieces.
It's the most stylish way to show your love of animals
and your support for the show.
So what should we talk about next?
Please let me know in the comments,
and be sure to subscribe for new episodes every week.
Thanks for watching.
Stay safe, and see ya!
[♪♪♪]
In 24 hours, there will be one shrew left on the island
and he'll be dead of starvation.
An excellent example of overpopulation.
Well, you know something, Doctor?
What's that?
I'm not gonna worry about overpopulation just yet.
[♪♪♪]