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Flamingos. They're so pink and namby-pamby,
the mascot of Florida, tacky lawn
ornaments, and cocktails on the beach.
They look silly with their strange beaks
and long legs and their pink plumage. Yet
visit the soda lakes of the African Rift
Valley, whose chemistry is so harsh
hardly anything can live in it. And what
do you find?
Flamingos. That's right. Their strange
looks are actually adaptations to
dealing with some of the harshest
chemical environments on earth. So here's
the deal. Soda lakes are caustic,
incredibly salty Lakes whose pH makes
them nearly impossible for most animals
to live in.
Yet flamingos choose to breed there. 75%
of the world's lesser flamingos have
their babies at Lake Natron in Tanzania.
Lesser is what the species is actually
called by the way. We're not just hating
on some innocent flamingos here. Other
species of flamingos have similarly
awesome capabilities but they're not as
laser focused on breeding on this one
caustic lake as the so called lesser
species. Soda lakes are named after the
caustic chemicals dissolved in their
water, not after your favorite brand of cola.
Soda lakes form in places where the
Earth's crust contain large amounts of
these chemicals thanks to volcanic
activity bringing them to the surface.
The lakes have a limited inflow and
outflow of water so the chemicals remain
very concentrated and the rising and
falling of water levels is mainly a
result of evaporation. The pH of these
lakes often sits between nine and ten
point five. That's alkaline enough to
burn unprotected human skin and eyes.
Like actual researchers exposed to this
water have sustained injuries even while
their flamingo subjects were just fine.
Practically the only animal that can
survive here full time are alkaline
tilapia, a fish adapted to tolerate high
pH. But even they retreat to the few
springs that feed the lake sometimes. Then
there's our flamingos. They have thickened,
specially adapted skin and scales that
help them resist burns. They can even
drink the lake water thanks to a
specialized gland they have that helps
them filter out and excrete the extra
salts. Oh and as long as the external
springs help to dilute the lake water
a bit. But these harsh conditions here
are perfect for two reasons. One, besides
the fish, basically no animals live here.
That includes predators that might like
to snack on baby
flamingos. The birds wait to build
their nest until evaporation drives a
water level low enough to expose small
islands in the center of the lake. That
way there's a sheltered place they can
fly or wade to but potential predators
still have to contend with that
treacherous water, so where flamingo
nests are is surprisingly safe. Secondly, we
keep saying that very few animals live
in the waters of soda lakes, but some
bacteria think it's just fine. These
include the cyanobacteria species that
is a favorite food of the lesser
flamingos. Cyanobacteria are also known
as blue-green algae,
even though they're not algae, they're
bacteria, and they're not always blue-green.
They're actually partly responsible for
causing Lake Natron to bloom with vivid
red and orange colors during the dry
season. Those red and orange colors come
from a large family of molecules called
carotenoids, the same pigment that give
carrots their orange color, hence
carrot-enoid. You get it. When flamingos
slurp up cyanobacteria, the carotenoids
could actually cause damage to their
tissues, so their livers process the
pigments and shut them down to where
they can't do any harm. Their feathers,
turning them pink. All flamingos get this
from their diets, which can also include
crustaceans and other sources of
carotenoids. But think about it. Lesser
flamingos turn pink because they've
evolved to thrive off of some of the most
chemically noxious hostile places on
earth and have a slightly toxic snack.
And then they decide they liked it so
much that they're gonna move in and
start a family. Which makes them pretty
hardcore for silly looking pink things.
Thanks for watching. If you enjoyed our
take on flamingo chemistry you might
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We'll see you next week.
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