BARBICEL

"The barbicel is a fine, stiff, hooked hair that helps birds to interlock their flight feathers."

"The barbicels can be seen under a microscope, as they are what give feathers their structure."

"During preening, birds use their beaks to zip and unzip the barbicels, keeping their feathers clean and in good condition."

"The complex arrangement of barbicels allows birds to have strong and aerodynamic wings."

"If a bird loses or damages its barbicels, it may have difficulty flying properly."