Orange Pigments
The visual perception of orange coloration is fairly common in marine invertebrates and for good reason. There are a number of true fluorescent proteins with emissions in the orange portion of the spectrum. Green fluorescence (such as P-496), when in combination with chlorophyll fluorescence and/or perhaps one of the true red fluorescent proteins (P-610, P-620, etc.) accounts for some cases of ‘orange’ fluorescence (Mazel, 1995). Some seem to be truly orange pigments, some of which are listed below, such as that noted in Cynarina lacrymalis (Logan et al., 1990). Mazel (1995, 1997) identified the orange pigment P-575 in the Caribbean Star Coral (Montastrea cavernosa). Blue-green (500 nm) and yellow-green (565 nm) wavelengths are most strongly absorbed. Mazel (unpublished data) also identified a similar pigment in the Orange Velvet Coral (Montipora digitata), with excitation wavelengths at 506 and 555 nm.
