Scanning electron micrograph (SEM) of a feather from a lanner falcon (Falco biarmicus). The feather has has a central stem called a rachis (not seen), off which branch numerous parallel barbs (blue). The barbs themselves branch into barbules (yellow), 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 found in Africa, southeastern Europe and western Asia.