Samples were measured at Rainbow Gardens, Lee Stocking Island, Exumas, Bahamas and Key Largo Dry Rocks, Key Largo, Florida. Both reefs are shallow patch reefs with typical of the Caribbean faunal assemblages. Reflectance was measured using a prototype hand-held underwater spectrofluorometer based on an Ocean Optics Model S1000 spectrometer controlled by a Tattletale Model 7 data logger (Onset Computer Corp.). The optical probes were held approximately 1.5 cm from the surface of the organism, providing a measured diameter of approximately 6mm. At about the same time we measured light from a 99% diffusely-reflecting surface (Spectralon, Labsphere, Inc.) to determine the relative ambent light levels. Reflectance was computed by dividing the reflected light at each wavelength by the wavelength specific upwelling light from the Spectralon surface.