The mechanism of light reflectance in silverfish

The reflectance of the common silverfish was first studied by Robert Hooke and is reported in his book Micrographia. Here we report a new study of the mechanism of the reflectance in the common silverfish (Ctenolepisma sp.). The reflectance from the body of the animal was measured with and without s cales using optical spectrophotometry. The structure of the surface region of the body of the animal was studied in cross-section using transmission e lectron microscopy, revealing a doubly chirped multilayer stack in the uppe r layers of the exoskeleton. By calculating the reflectance of this multila yer, it is shown that it accounts for most of the visible reflectance but w ith a large deficit in the infrared compared with observation. The scales o f the silverfish give rise to some absorption in the visible and the period ically spaced ribs give rise to some reflectance in the infrared. Modelling the ribs as an array of chitin cylinders accounts for the reflectance of t he scales. The remainder of the observed reflectance in the infrared is att ributed to reflectance from the body of the animal underneath the multilaye r stack.