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These
are the two species of Old World flamingos, the greater
(upper
left) and the lesser (bottom right). Their ranges are
included,
pointed out by the convenient arrows. Even though
the
pictures don’t show it because I couldn’t get them to stand
next
to one another, the greater is twice the height of the lesser,
hence
the names. Notice the color variation as well. However,
color isn’t based on species.
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The greater flamingo
(Phoenicopterus roseus) is much
larger than the lesser flamingo (Phoenicopterus minor) –- that makes sense. Greater
flamingos average about 140 cm (55 in) tall, but they only weigh about 3 kg
(6.6 lb). They're mostly legs, and there isn’t a lot of meat on those legs. If
given a choice at the next flamingo fry, choose a breast over a drumstick.
The lesser flamingo weighs in at only 2 kg (4.4 lb) on average
and are half as tall as the greater flamingo. But they make up for this in
numbers. There are over 1.5-2.5 million lesser flamingos in East Africa, maybe
twice as many as the greater flamingos, even though the larger species has a
much broader range.
Flamingos are freaky birds. Their knees seem to bend
backwards, but it's just an illusion since those backward bending joints are
really their ankles. They tend to stand on one leg, and the reasons for this
are not completely known. Some birds do it for camouflage, since on one leg
they look more like branches. This probably doesn’t work for flamingos – since
they’re pink!
A 2010 study showed that flamingos stand on one leg much
more often when they are in water, so they hypothesized that they do it to
reduce the amount of body heat that is lost to the water. Also, the scientists
saw that the flamingos stood on one leg in the water for less total time as the
temperature increased. This was definitive proof for leg position as a method
of thermoregulation.
Other theories state that flamingos might stand on one leg
because it takes a lot of energy to pump blood down and then back up those long
legs Birds live on the edge of starvation everyday; by pulling up one leg
at a time, they can reduce the distance and therefore the energy needed for
moving blood. Or, they may do it to reduce the fungal and parasite loads on
each leg – that last explanation is weak, I think.
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All
species of flamingos feed by turning their heads upside down.
In
this way, they can scoop in some water and filter out their
food.
Evolution is funny, they could have just evolved scooping
lower
jaws, but for some reason they have scooping upper jaws
and
therefore turn their heads over. Remember that evolution is
a point
to point exercise in mutation and possible
benefit; it
doesn’t
move toward simple or toward logical.
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Flamingos also have those funky looking beaks, but they’re
functional because they eat with their heads turned upside down. As a result,
it’s their lower jaw that is fixed and their upper jaw swings free. They don’t
use their jaw to chew their food; they don’t really have teeth.
Instead, flamingos are filter feeders. This isn’t unheard
of, there are other birds that filter their food to keep only things within a
certain size range and then swallow them whole, but they are the biggest of the
filter feeding birds. When their two jaws come together, they form a sort of comb
assembly on the sides, the wider the distance between the comb’s “teeth,” the
bigger the objects that can fit through.
Old studies shows that they use the “teeth”
(actually called lamellae) to
exclude things that are too big, and then to filter out things that are too
small, like excess water. The tongue sits in a deep groove and pulls in and
pushes out water and those things it doesn’t eat. This pumping occurs up to 20
times per second in lesser flamingos and 6-8 times/second in greater flamingos
(see this video and watch for water squirting out). Different bill shapes and
different spaces and lamellae sizes are specific to each species, and each eats
according to its filter.
The popular answer for why flamingos are pink is because of
their diet. All that stuff we talked about above is related to that answer,
but you can now sense that it’s a little more complicated. The greater and
lesser flamingos have different filters because they eat different things. Yet
they both end up pink.
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Here
are the major source of nutrition for the Old World flamingos.
On
the top left are the brine shrimp that make up the majority of
the
diet of greater flamingos. On the bottom is A.
fusiformis, the
major
calorie provider for the lesser species. On the top right are
spirulina
tablets from a health food market, made from dried
Arthospira organisms. Notice that none
are pink, yet the flamingos
are
pink. Just how do they pick up color from their food?
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Cyanobacteria are sometimes called, perhaps incorrectly,
blue-green or red algae. Alga has no clear-cut definition; some consider
anything with chlorophyll and no protective cells over their gametes to be an
alga, but others exclude all prokaryotes from the classification. I think
the term cyanobacteria (Cyanophyta) is much
more accurate.
The cyanobacteria that lesser flamingos eat used to be
called Spirulina, but are now
classified as species of Arthospira. A. fusiformis is the main dietary source
of nutrition for lesser flamingos (of course greater flamingos eat them too;
their filters let them in and keep them in), but there is also A. maximus. Together, they make up the
spirulina that is popular in health food markets today.
We said above that the answer to today’s questions was that
flamingos are pink or orangish based on the food they eat. But their food isn’t pink or orangish!! Look at the picture, spirulina is green.
The explanation is related to something you see every year, and is something we
have talked about before. It’s just like how the leaves turn colors in Autumn.
The green leaves in summer have red and other pigments, but they’re
masked by so much chlorophyll (see this post). In fall, the leaves stop making
chlorophyll, so the other colors shine through. The spirulina and brine shrimp have
red and yellow pigments, but again there is so much green that the other colors are
masked.
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Here
are two lobsters. Actually, it’s one lobster and one dinner.
The
only difference is boiling water. The carotenoids in the shell
of
the live version are bound to proteins and this changes their
light
absorbing and reflecting properties (color). The hot water
denatures
the proteins and frees up the carotenoids to be the
color
they always dreamed of being.
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There's another reason for the different colors of food and
flamingo. The pigments are sometimes complexed to proteins, and this can make
them look brownish, bluish, gray, or green – like the many species of brine
shrimp, aquatic beetles, and larval flies. This is very similar to lobsters and
shrimp. They're bluish or grey when scooting around in the water, but turn
red/pink when they are cooked.
Carotenoids come in many varieties; their chemistries run
the gamut from alcohols to esters to plain hydrocarbons. We see them in carrots
(alpha and beta carotenes - orange) and tomatoes (lycopene - red) for example.
Spirulina has many carotenoids, but the one there in highest concentration is
called astaxanthin (pink, as in salmon meat). The percentage of different
carotenoids and the total amount of them in the diet determines the color of the feathers and skin. This is why
some flamingos can be bright orange, while others are very light pink.
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These
are just a few of the dozens of carotenoids found in nature.
The
longer the carbon chain, the lighter the color, from red to
yellow.
This is just a basic generality, different side chains and
rings
can alter the color well. And just to let you know, carotene
was
named for carrots, not the other way around.
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For lesser flamingos, their food is sometimes their doom. A 2006 study found that blooms of toxic cyanobacteria produce two different
toxins (microcystin and anatoxin) and have been responsible for several die
offs in lesser flamingo population over the last 20 years. They have also found
that in some instances, the spirulina they eat will also produce toxin, but
they don’t know if it is enough to kill them. Microcystin from an algae bloom is the same toxin that shut down the Toledo water system earlier this week.
What may be worse, a bacteriophage
(a virus that infects bacteria, see this post) has been increasing in the
alkaline lakes where the spirulina grows according to a 2014 study. It infects
and kills the A. fusiformis. The kill
off of the cyanobacteria leads to a trophic
cascade effect; the average adult needs 70 grams of A. fusiformis a day to survive, and that is dry weight, not
saturated with water. Lose the base of the food chain and everything else loses
too.
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Lake
Natron is VERY salty, and it contains lots of other minerals.
Natron
is a combination of salt and minerals that the Egyptians
used
to mummify the bodies of those who could afford it. Not
everyone
got to be mummified; if that were the case, we would
have many undead walking around, placing curses on
successful
tomb hunters. The minerals are so concentrated that
dead
animals that fall in end up mummified and calcified. They
look
like gargoyles on a French cathedral.
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Next week, another question to investigate - can living anything short of an astronaut make it to space?
