They're one of the largest rodents in the world, they're indisputably adorable, and
hey, Canada doesn't put just anyone on their money.
But the main reason you should appreciate beavers is that they're second only to us
in their ability to completely transform the environments they live in.
Usually for the better, though.
While we like to surround ourselves with warehouse stores and hamburger restaurants, beavers
will turn a stream-fed meadow -- even a patch of desert -- into a lush, watery habitat for
all sorts of wildlife, aquatic and land-lubber alike.
They do it, of course, by building dams.
And darn, can these guys dam.
Most beaver dams are 5 to 10 meters long and form small ponds behind them.
But sometimes these structures have been known to turn into decades-long development projects.
The biggest beaver dam in the world, in Canada's Wood Buffalo National Park, is more than 850
meters long, forming a huge wetland that's actually been photographed from space.
It's been under construction since the 1970s, with subsequent generations of beavers adding
to it, and it's getting bigger every year.
Beavers go through all the trouble of dam-building primarily for defense.
Some build lodges made of sticks and mud in the ponds that they create, while others burrow
into their muddy banks.
Both are designed to be entered only underwater.
By surrounding themselves with deep water, beavers can protect their dens from predators
like wolves and wild cats, while creating a habitat that supports the aquatic plants
they like most, like cattails, willows, pondweed and aspen.
The dams are usually started by single males trying to attract a mate, or a young couple,
which pair up for life.
Adorable beaver love.
But one thing that's a little less cute is how completely serious these guys are about
their dams.
Scientists call it instinctive behavior, but it can end up looking kind of compulsive.
Biologists believe that the sound of running water actually triggers dam-building behavior
in beavers.
Some theorize that beavers may even be able to feel, or otherwise sense in the water,
when a leak has sprung in a dam.
Research has shown that little gaps intentionally created in a beaver dam will cause the members
of a colony to drop everything to repair it, regardless of whatever else needs to be done.
Scientists — a little evil — have even played audio recordings of running water near
beaver sites, and have returned in the morning to find the speakers covered with sticks and
mud.
This obsessive engineering is all made possible by beavers' trademark teeth.
And you may have heard that their teeth continue grow throughout their lifetimes, which is
true -- but only their big, curved front incisors.
Beavers' voluminous tree-gnawing keeps their teeth from growing too long, but they don't
actually eat through trees.
They actually prefer to feast on non-woody plants, like water lilies and cattails, in
the spring.
In winter, they strip trees of their bark and the layer of soft tissue underneath known
as cambium.
And, despite what cartoons have taught us, beavers' famous front teeth aren't white,
they're ORANGE because their tooth enamel contains iron, which makes them incredibly
strong and sharp -- even though it makes them look like they have a two-pack-a-day habit.
And finally, a note about beaver butts.
They smell DELIGHTFUL!
Both male and female beavers have a pair of anal scent glands that they use to mark their
territory.
And the yellowish oil that they produce, called castoreum, smells precisely like sweetened
vanilla ...
... so much so that for hundreds of years it was used to flavor food and drinks and,
in some places, can still be found in perfumes and processed foods under the ambiguous moniker
of "natural flavoring."
Other cultures have prized castoreum for its medicinal properties.
And that might be because one of beavers' favorite snacks is the bark of willow trees,
which contains the chemical salicin, which people have used for centuries to make natural
pain-killers.
But because beavers eat so much of the bark, their sweet-smelling butt-oils can be chock
full of salicylic acid, which is the precursor compound to aspirin.
Now -- what other animal can you think of that makes its habitat more livable, drops
everything to keep its neighborhood safe, and has a bum that smells like dessert?
I can't come up with anything.
Thanks for watching this SciShow Dose!
If you'd like to learn more about all kinds of animals, check out our partner channel
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