Hair, there and everywhere: A comparison of bat wing sensory hair distribution.

Bat wing membranes are composed of specialized skin that is covered with small sensory hairs which are likely mechanosensory and have been suggested to help bats sense airflow during flight. These sensory hairs have to date been studied in only a few of the more than 1,400 bat species around the world. Little is known about the diversity of the sensory hair network across the bat phylogeny. In this study, we use high-resolution photomicrographs of preserved bat wings from 17 species in 12 families to characterize the distribution of sensory hairs along the wing and among species. We identify general patterns of sensory hair distribution across species, including the apparent relationships of sensory hairs to intramembranous wing muscles, the network of connective tissues in the wing membrane, and the bones of the forelimb. We also describe distinctive clustering of these sensory structures in some species. We also quantified sensory hair density in several regions of interest in the propatagium, plagiopatagium, and dactylopagatia, finding that sensory hair density was higher proximally than distally. This examination of the anatomical organization of the sensory hair network in a comparative context provides a framework for existing research on sensory hair function and highlights avenues for further research.