Cutlip minnows, a species of small fish that inhabit streams, could be described as the master interior decorators of the fish world.
Working with collaborators in eastern Ontario, Canada, Andy Bramburger, a research associate at the University of Minnesota Duluth’s Natural Resources Research Institute, found that male cutlip minnows carefully select pebbles that are darker and more color-saturated than the streambed background to construct their conspicuous mound-shaped nests. The researchers noticed the nests while conducting regular surveys of the stream and wondered if the fish responsible for building them were indeed choosing nesting materials based on color.
Their findings were published in the Journal of Fish Biology.
Along with several students, Bramburger and Brian Hickey from the St. Lawrence River Institute of Environmental Sciences located recently-constructed cutlip minnow nests during the nesting season in April. Once the eggs had hatched and male cutlip minnows—who build and defend the nests—and juveniles had left the stream, the researchers collected pebbles from nest sites as well as from background areas of the streambed. They used a digital camera system and image analysis software to measure the wavelength, color saturation, and brightness of similarly-sized nest and background pebbles.
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Image via University of Minnesota.