Herring skin flaunts physics-defying optical properties
In the world of optics, one expects that modern science can fully explain the visual characteristics of any material. But researchers at the University of Bristol have just stumbled across a seemingly inexplicable optical phenomenon in the skin of silvery fish such as herring and sardines.
According to the scientists, these fish are "breaking" a basic law of physics. The multilayer fish skin, which is made of light-reflecting guanine crystals, would normally be expected to polarize light and thus reduce its effective reflectivity. But the incorporation of two different types of crystals effectively avoids polarization.
"We believe these species of fish have evolved this particular multilayer structure to help conceal them from predators, such as dolphin and tuna," said Nicholas Roberts in a university press release. "These fish have found a way to maximize their reflectivity over all angles they are viewed from. This helps the fish best match the light environment of the open ocean, making them less likely to be seen."
The researchers' discovery could result in the creation of more sophisticated material surface treatments and optical devices. According to Ph.D. student Tom Jordan, "Many modern day optical devices such as LED lights and low loss optical fibers use these non-polarizing types of reflectors to improve efficiency. However, these manmade reflectors currently require the use of materials with specific optical properties that are not always ideal. The mechanism that has evolved in fish overcomes this current design limitation and provides a new way to manufacture these non-polarizing reflectors."
Blaine Brownell is a regularly featured columnist whose stories appear on this website each week. His views and conclusions are not necessarily those of ARCHITECT magazine nor of the American Institute of Architects.