#Genus: Graphium

[haveyouseenthisanimal-irl]

Range: Southeast Asia

[untitledgoosegay]

Re: the difference: a "pigment" can, at least hypothetically, be extracted and retain its color. It's a specific molecule, e.g. carotenes (bright yellows, reds, and oranges), or melanins (browns, blacks, and more coppery reds). "Structural coloration," aka iridescence, is formed by molecules which don't in isolation have the color they appear to -- e.g. structural blues in birds, which are complex arrangements of microscopic melanin crystals within keratin nanotubes. That melanin on its own is black or grey (which is why most 'blue' birds appear grey when they're wet!), but when it's structured in that precise way within a feather, it refracts blue light to the eye. (Relatedly, most greens and blues are structural blue over yellow or red pigment.) (This is also why we can know the colorations of some extinct dinosaurs! Fossilization can preserve even those microscopic structures and pigment traces, which is how we know that Microraptor was shiny black like a crow, and Sinosauropteryx was ginger with a stripy tail.)

The question of true blue pigments in nature led me down a rabbit hole -- as far as animals go, it appears that only a handful of butterflies (!) display true blue pigments. Butterflies in the genus Nessaea produce a blue pigment called pterobilin; there's also phorcabilin and sarpedobilin, found in the Graphium and Papilio genera. Some birds color their eggs with a blue pigment called oocyanin, but they don't use this in feathers. Other apparently "blue" eggs are colored with biliverdin, a green pigment that can appear bluish under some circumstances.

Blue flowers and fruits primarily use pigments called anthocyanins, which can be anywhere from blue to red depending on pH and other factors, including incorporating metal ions -- so you could argue that anthocyanins aren't "truly" blue, but imo that's splitting hairs.

Thank you for asking! I learned a bunch while poking after this question.

as funny as it is to say, "theres's no such thing as a fish" is not actually true

"science doesn't know what a fish is" is really not true

"fish" is not a monophyletic category. there is no common ancestor of everything that we call a "fish," and none of the things that we don't

"fish" is a paraphyletic category -- and a useful one! marine biologists use it! "fish" describes a general body plan and lifestyle. it is useful to be able to talk about coelacanths and tuna in a shared category, though coelacanths are more closely related to us than to tuna.

where this bugs me is the repetition of the idea that "scientists" are hidebound and uncreative, unable to comprehend anything that doesn't conform to a specific idea of categorization -- when this is fundamentally untrue! we know perfectly well what a "fish" is. the fact that it's a paraphyletic group is only confounding to pop science, as a funny factoid, not to anyone who actually understands what a paraphyletic group is.

[wotafoto]

☼ Green triangle ☼

Graphium agamemnon - day butterfly from the genus Grafium, family sailfish. Named after the Mycenaean king Agamemnon. It is also called a green triangle, I really loved this butterfly, it is very active and expressive, my favorite coloring of butterflies! ☼ Зеленый треугольник ☼ Graphium agamemnon — дневная бабочка из рода Графиум, семейства парусники. Названа в честь микенского царя Агамемнона. Ее еще называют зеленым треугольником, я очень пол...

http://ift.tt/2sttvA6