Mammalian fur is a highly adaptable structure, with a broad range of well-documented functions. Many small animals, including shrews, most rodents, and some marsupials, have fur composed of at least four types of hair, all with distinctive and complex anatomy. A ubiquitous and unexplained feature is periodic, internal banding with spacing in the 6–12 μm range that hints at an underlying infrared function. One bristle-like form, called guard hair, has the correct shape and internal periodic patterns to function as an infrared antenna. Optical analysis of guard hair from rodents, shrews and antechinus shows precise tuning to the optimum wavelength for thermal imaging. An infrared sensory capability, that provides all-round infrared threat-warning, could explain why common predators of rodents, such as, small cats, snakes and owls have adaptations to conceal their infrared emission. There are many other well-recognised infrared sensors in members of the Reptilia, Insecta, Arachnida, and Mammalia Classes. Such hair structures are not present in bats (aerial predator) and moles (subterranean). Preliminary evidence suggests that wild mice and rats react to infrared sources, but further experimental evidence is required to confirm these results. The tools developed in this work may enable us to understand the other hair-types and their evolution.

The data set contains anatomical data for hair types from rodent, shrew and antechinus fur to build evidence that these are infrared sensors. The data was measured on a microscope and there was no processing apart from scaling. The data also includes details of numerical calculations on the sensor performance with detailed description of how the calculations were performed.

The .wmv file is a video compilation of filming clips from the Leonardo Merlin thermal imaging camera. The video can be played on any system that can read WMV files.