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嗨 我是Jessie 这里是动物奇迹
Hi, I’m Jessie and this is Animal Wonders.
I was recently asked by one of our young viewers
how ducks keep their feet from freezing in a cold lake.
And I’m excited to be able to talk about it.
ANIMAL WONDERS MONTANA
I’m constantly surprised by some of the incredible adaptations
certain animals have to survive in extreme environments.
Like emperor penguins in the frigid cold of Antarctica,
Egyptian sandfish escaping into the sand of the desert,
and anglerfish thriving in the deep dark of the ocean.
So when I look at an animal like a duck,
it’s sometimes easy to overlook the fact that
they can swim in seriously cold water
or stand on ice and not have their feet freeze solid.
And this is all because of an amazing thing called Countercurrent Heat Exchange.
What’s happening is the warm blood
from the duck’s body flows down their leg,
and comes into close contact with cold blood
traveling from their foot back up their leg.
The close contact between the hot and cold blood
brings the temperature of warm blood down
and increases the temperature of the cold blood.
This does two things:
The temperature of the cold blood going back into their body,
heats up so it doesn’t bring their core temperature down.
And the warm blood gets colder before it reaches their foot,
so the temperature of their foot and the temperature of the ice are closer together.
Let’s look at this a little closer.
Heat exchange happens when there’s a difference in temperature between two objects.
The bigger the difference in temperature,
the quicker heat will move from the hot object to the cooler object.
If there’s less of a difference in temperature,
the heat exchange will be slower.
So, when the warm blood from a duck’s body travels down their leg
and gets cool by the blood traveling up from the foot,
the difference between the temperature of the ice and their foot gets smaller,
which means that by the time the blood gets all the way down to their foot,
it’s quite cold and the heat exchange decreases.
惊讶的是 鸭子站在冰上时 脚部的热量
Surprisingly, ducks that are standing on ice
lose only about 5% of their heat from their feet
and they lose 95% from their body,
even though they’re covered in warm feathers.
The Countercurrent Heat Exchange System helps them survive in the cold temperatures.
And the same system works for other animals, too.
Like arctic foxes,
who walk on and dig in snow for long periods of time.
This is Cas and he’s showing off his amazing winter coat.
His fur will definitely help.
But it’s not the only thing that will help him survive in the cold.
Arctic foxes also have countercurrent heat exchange systems in their paws
to keep them from freezing,
and to reduce the loss of body heat during the extremely cold winters.
You have super paws, buddy!
Now, Countercurrent Heat Exchange Systems not only work for cold weather animals.
They also help animals who live in hot environments, too.
Flamingos are famous for their pink feathers and long legs.
But not many people know
that the waters they stand in can get incredibly hot.
The shallow waters they hunt for food in
can get up to 115 degrees Fahrenheit.
And they could quickly become overheated
if they didn’t have something to protect them.
Flamingos also have the same
countercurrent heat exchange system in their legs like ducks do.
But instead of keeping them warm,
it helps cool them off.
Remember that the smaller the difference in temperature between two objects
the less heat exchange will take place.
So for flamingos, their body temperature is
cooler than the hot water they’re standing in.
The cooler blood travels from their body into their leg,
and as it goes down it intertwines with hot blood
coming up from their lower leg and foot.
That heats up the cooler blood.
So when it reaches the water,
it’s closer in temperature.
So the heat exchange from the water is less dramatic than it would be.
If the temperature difference was bigger,
the hot blood then comes back up their leg toward their body,
and it is cooled down by the blood coming down,
which makes sure they don’t pump hot blood back into their body.
And you’ve seen flamingos standing on one foot, right?
They do this because it’s more efficient.
Because they only have one foot in the hot water,
it reduces the exchange of heat
from the water to their body even more.
So this seemingly simple thing that ducks and flamingos can do
is more complicated than it looks.
Thanks for being curious and learning with me.
If you’d like to continue going on adventures,
be sure to subscribe.
And if you have any questions you’d like me to answer,
leave them in the comments below.
Now I love learning about animals and how their bodies work,
which is why I recently watched this video
called What Animals See on CuriosityStream.
I enjoyed revisiting some information I thought I knew pretty well,
but realized I hadn’t explored fully.
And now I’m eager to continue delving down the rabbit hole once again.
You can find the video on CuriosityStream
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Thanks and we’ll see you next week.
ANIMAL WONDERS MONTANA