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Murray Edwards College
University of Cambridge

School Winner: Why Are Flamingos Pink?

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    02 Nov

    Science fact

    Elephants rarely get cancer: less than 5% of captive elephants die of cancer, compared to 20% of humans. Elephant genomes have at least 20 copies of the tumour suppressor, p53, which may explain their low cancer rates relative to humans, who have only one copy. 

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    I can vividly recall the summer of 2008 in Sri Lanka, looking out of my hotel window and my eyes beholding a bright, fluorescent pink…it was a flamingo. With its broad curves and long stick-like legs that made up most of its height (90-150cm), I had never witnessed such a magnificent creature: a beautiful coral with tints of rosy pink beneath their feathers. Surprisingly, flamingos aren’t born pink, despite their name deriving from the Spanish word flamengo meaning “flame-coloured”.

    Baby flamingos are born with grey feathers, which colour to pink as they grow older due to their diet. The phrase ‘you are what you eat’ applies to the pink flamingo. However, some flamingos can also be tangerine or white, depending on what they eat and how much of it. The most popular pink colour is due to shrimp, plankton, blue-green algae, and other crustaceans and molluscs that flamingos commonly eat. Once eaten, the liver would break down the organic pigments or ‘carotenoids’- a pink and orange pigment molecule that are also found in carrots and beetroot.

    The algae and shrimp aren’t as pink as the flamingo because the carotenoids begin as part of other compounds, such as astaxanthin which is bonded to a protein and affects the way the carotenoid inside it absorb and reflect light. The blue part of the spectrum is reflected instead of the red part, but once the flamingos digest the food, their digestive enzymes detach the pigment from the proteins, and once they’re free, the pigments start reflecting red light. These molecules can then be absorbed in fat and distributed to the feathers, face and legs of the flamingo. Gradually, over 2 to 3 years, accumulating fats slowly turn the feathers into that iconic shade of pink.

    To give off that pink hue, carotenoids are mainly found in algae, so flamingos who eat more algae will essentially be brighter in pink to those that may only eat insects and small fish, where the pigments can be diluted.

    The colour change can occur in humans too as we eat some foods that are high in carotenoids, like apricots and mangoes. If you eat too much of these foods, your skin can turn orange- a condition known as carotenosis. However, our diets are much more balanced and consists of a wider selection, so there’s no need to worry of our skin or hair turning a different shade!

    Afnaan Firthous
    Newham Collegiate Sixth Form Centre

    "My name is Afnaan Firthous and I’m currently in Year 12 at the Newham Collegiate Sixth Form Centre. I’m studying Biology, Chemistry, Maths and Psychology A Levels and with these subjects I’m hoping to study either natural sciences or neuroscience at university."