Researchers Look for the Origin of Blue Morpho Pigment in Butterfly Fossils

Butterflies display some of the most breathtaking hues on their wings. Most of them come with bright colors and flashy patches, but there are others that bring a metallic shine to cold colors. The blue morpho butterfly fits this category, thought by many to be unique on the planet. This is why researchers from the Chinese Academy of Sciences wanted to see where the exquisite hue came from.

The blue morpho butterfly is a source of fascination both for scientists and for aestheticians. Its wide wings are colored in a beautiful metallic blue that casts iridescent flashes. These flashes leave the impression of shimmering. In a way, the wings of this insect glow, but not in the classical sense.

Instead of emitting light, its metallic wings refract it. This produces the light sensation we can also see in other insects, but also in birds or some marine creatures. From all of them, butterflies and other creatures in the Lepidoptera family are well-known for the color patterns they have on their wings.

Some might seem plain, but others impress their watchers with intricate color schemes and shapes, or by imitating the hues of other poisonous animals. The most interesting ones are those with metallic colorings, including the blue morpho as well. This attracted the attention of scientists, who decided to find out how long these patterns and nuances date back in the evolution of the species.

Why Is the Blue Morpho Special?

This butterfly doesn’t have a regular color on its wings. Its pigment is called structural color. This is made up of a series of physical blocks of material that are put together like in a prism. Then, they refract light and produce the beautiful iridescent effect. These prismatic materials are invisible to the naked eye but create structured on butterfly wings, peacock feathers, or insect shells.

The refractive materials are usually arranged on butterfly wings in different formations. However, they are not present only in blue morpho specimens. After identifying them in several other related species, researchers knew this was an evolutionary trait of the Lepidoptera. However, where do these patterns come from?

Blue morpho butterfly on a leaf

The blue morpho butterfly surprises with its metallic shade and subtle glow.

Cracking the Mystery of Special Blue Morpho Pigment

At first, scientists selected over 500 fossilized butterflies to study their wings and pigments. From all of these, they picked only six that had their wings well-preserved. This way, they could collect all the data there is about them.

These specimens are about 200 million years old but have lost the color in their wings. However, scientists could still collect data, as these wings still had an intact nanostructure. With the help of a special electron microscope, they identified the patterns and then developed some computer models after them.

After manipulating these structures on the computer, they found out how they could refract light. Also, decoding these structures showed them what colors their wings had. Their main nuance was brown, but they also had a metallic tinge. Therefore, this feature was one of the first distinguishing marks of the Lepidoptera.

This slowly gave rise to the multitude of color patterns and iridescent shades on butterflies’ wings. The first time when these optical illusions found their way on butterfly wings was in the Cretaceous. Of course, there was a long way to today’s blue morpho butterfly, but the start was humble yet determined.

Researchers published their findings in the journal Science Advances.

Image source: 1, 2.

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William E. Eubanks
 

I'm one of the main writers on the site; mostly dealing with environmental news and ways to live green. My goal is to educate others about this great planet, and the ways we can help to protect it.

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