Abstract
Here I present the results obtained by scanning male adults of two mayfly (Ephemeroptera) species with a high resolution micro-tomographic scanner, allowing observation of external structures, with similar results to those obtained under scanning electron microscopy. Moreover, this non-destructive technique permits investigation of the internal structures, and to “navigate” inside them, in a way never before imagined. Moreover by using different transfer functions and in accordance with the X-ray transparency, it is possible to assign different colours to highlight different anatomical parts, and to obtain “aesthetic” images. Results are compared and discussed with previous findings. It is postulated that differences in the diameter sizes of the ommatidia, when comparing dorso-frontal and ventro-lateral parts of the compounds eyes, represent an evolutionary advantage enabling increased accuracy in movement displacement detection of competing males within the swarm.