On the perception, production and function of blue colouration in animals

Abstract

Bright colouration in animals has long attracted the attention of physicists, chemists and biologists. As such, studies on the functions of colours are interdisciplinary, focusing on the mechanisms of colour production and maintenance, the physical and chemical properties of the colour-producing elements, and visual systems and behaviour of potential receivers. Blue colouration has received a large share of research attention and is fascinating for several reasons: blue has been attributed to a very broad range of functions, blue is achieved by a great variety of mechanisms (although their production and maintenance costs are currently unclear), and the blue part of the spectrum (450-490 nm) can be perceived by most taxa. This review explores the breadth of studies that propose a function for blue colouration. In so doing, it discusses the diversity of ways in which blue colours are produced both as pigments and structural colours, and that blue visual pigments are common across a broad range of taxa. This analysis of the current literature emphasizes the importance of multidisciplinary hypothesis testing when attempting to elucidate the function of colours, the need for manipulative over correlative evidence for the function of colours, and, as colour research becomes evermore interdisciplinary, the need for well-defined consistent terminology.

Blue reflectance in tarantulas is evolutionarily conserved despite nanostructural diversity

“…Throughout living organisms, blues are almost always produced by structural mechanisms, ranging from quasi-ordered structures to 1D, 2D, and 3D photonic crystals ( 23 , 24 ). Blue coloration in birds and insects is often produced by quasi-ordered or multilayered structures (that is, 1D photonic crystal), and we found that these two structural mechanisms also produce blue in tarantulas.…”

Warning Signal Efficacy: Assessing the Effects of Color, Iridescence, and Time of Day in the Field

“…Investigations of warning colors to date have largely focused on long‐wavelength, diffusely reflected colors (e.g., oranges, reds, and yellows; Umbers ). Stevens & Ruxton () propose that long‐wavelength colors may be more effective warning signals than short‐wavelength colors (e.g., ultraviolet, blue, and green) because they (1) are more conspicuous when viewed against green foliage, (2) are more reliably seen across a diversity of habitats, (3) permit distance‐dependent camouflage, and (4) are distinctive from colors displayed by profitable species.…”

Studies in Mexican Grasshoppers: A new species of Pedies Saussure (Acrididae: Melanoplinae) with comments on the unusual blue coloration on the abdomens of females and live specimen images for three other congenerics

“…This coloration is very vivid in live females, but is also observable to some degree in pinned specimens. Other colors, such as red, orange, and yellow, are due to the presence of carotenoids, but blue pigments are more rare because the required chemistry is more complex (Umbers, 2013). This coloration might be used by conspecifics for sex identification, although in Australia Umbers (2011) found that males of the chameleon grasshopper Kosciuscola tristis Sjöstedt change color in response to temperature.…”