MOSQUITO EYE DESIGN - CONICAL RHABDOMS ARE MATCHED TO WIDE-APERTURE LENSES

Night-active mosquitoes have photopigment-containing rhabdoms that tak e the form of a wide hollow cone, with the distal apex at the focus of the ommatidial lens. It is shown geometrically, and with the aid of a gelatin model, that such a structure can trap light over an angle of up to 60 degrees, roughly equal to the width of the cone of light prov ided by the lens. This gives a gain in light-gathering power of up to nine times that of the more usual cylinder-shaped rhabdom with an acce ptance angle of less than 25 degrees.