This article was originally posted on RealClearScience.
There are two varieties of flamingo in the world: The first is a majestic bird that makes its home in warm coastal waters all over the world. The second is a plastic ornament — and official city bird of Madison, Wisconsin — that deeply troubled and misguided souls believe will add a touch of class to their lawns. Fortunately, this article is about the former, not the latter.
Flamingos are known for their beautiful red and pink plumage which comes from pigments called carotenoids. (Carotenoids come in a variety of shapes and colors. Red, orange, and yellow vegetables, such as carrots and peppers, contain carotenoids.) Flamingos are unable to produce their own carotenoids. Instead, they aquire them from their diet. Once in the bloodstream, the carotenoids make their way to follicle cells and then into the feathers.
Diet, however, appears not to be the only source of coloration. In a new paper in the journal Scientific Reports, Korean researchers show that flamingo feathers are covered with haloarchaea, a type of extreme salt-loving microbe. Haloarchaea also come equipped with carotenoids, which they use to produce energy in a rather bizarre way that is more akin to solar power than to photosynthesis.
The authors studied captive flamingos that had been fed an artificial diet that lacked carotenoids and subsequently examined the birds’ feathers. They isolated 13 different types of haloarchaea and confirmed the presence of bacteriorubrin, a red-colored carotenoid. Thus, these extreme salt-loving microbes were responsible for the eye-catching color of the captive flamingos.
Of course, wild flamingos are not fed an artificial diet that lacks carotenoids. The natural coloration of wild flamingos, therefore, would be the result of both diet and environmental factors, such as the decorative microbes described above.
The harmonious symbiosis between bird and bug is almost enough to make me purchase a plastic knickknack of my own. Almost.
Source: Kyung June Yim, Joseph Kwon, In-Tae Cha, Kyung-Seo Oh, Hye Seon Song, Hae-Won Lee, Jin-Kyu Rhee, Eun-Ji Song, Jeong Rae Rho, Mi Lyu Seo, Jong-Soon Choi, Hak-Jong Choi, Sung-Jae Lee, Young-Do Nam & Seong Woon Roh. “Occurrence of viable, red-pigmented haloarchaea in the plumage of captive flamingoes.” Scientific Reports 5, Article number: 16425. Published online: 10-November-2015. doi: 10.1038/srep16425