20 Like hair and claws, feathers are made from a substance called keratin, which makes them strong and flexible. As feathers develop, they split apart to form a mesh of fine, parallel strands called barbs that lock together to create a smooth surface. Breakable plumage The central American motmot changes the shape of its tail feathers while preening. When it pecks at a feather, the barbs break off, leaving a bare shaft with a spoon-shaped tip. Emerging feather Protective sheath Skin Fully grown feather Feathers within feathers Under high magnification, barbs and barbules look almost like miniature feathers. Magnification of macaw feather showing barbs and barbules Only the parallel barbs are visible in this magnified flight feather Filoplumes These hairlike growths are found between the feathers on a bird’s body. Split feathers Some feathers split to form two different halves on the same shaft. Quill Second shaft Barbs Feathers start growing as pulp inside tubes called sheaths or pins. The tip emerges from the sheath, unrolling and splitting to form a flat blade. Eventually the sheath falls away, leaving the fully formed feather. HOW FEATHERS GROW Shaft The hollow shaft contains the dried pulp remains. Barbs locked together to form a smooth surface Quill Shaft Downcurved edge Hollow interior Quill tip attached to muscles Pulp from interior of shaft