Fluorescence at joints in a flagellum. (A) Patches of fluorescence at joints between the proximal annuli of the flagellum of a crayfish maxilliped 2 at their normal resting position. (B) The same patches distorted when the curvature of the flagellum was forcibly decreased. (C) Setae on the flagellum of maxilliped 2 of a crayfish. Fluorescence is restricted to a ring at the base of each seta. (D) Flagellum of maxilliped 2 in a crab Carcinus to show the fluorescence at the base of each seta. Scale bars 200 μm.