Scanning electron micrograph (SEM) of a wing feather from a lanner falcon (Falco biarmicus). The feather has numerous parallel barbs, which branch from a central stem called a rachis (not seen). The barbs themselves branch into thin parallel barbules, which terminate in tiny hooks (barbicels), which attach to the adjacent barbule. These links allow the feather to present a flat blade. The lanner is a large falcon that inhabits open country in Africa, southest Europe and western Asia. This feather has not been cleaned during preparation, and the barbs move due to electrostatic interactions during the scans.