Photophores emit light at a slightly different wavelength and
more importantly, have a much narrower spectral bandwidth than
that of secretory luminescence. It
has been suggested that the dual visual-pigment system allows
Clade 1 oplophorid shrimp to distinguish between these modes
of bioluminescence. Light of different bandwidths and wavelengths can have varying
stimulatory effects on a given photoreceptor, and the mismatch
and combination of more than one visual pigment may allow the
shrimp to discriminate between different spectral characteristics. Another proposal is
that the dual visual-pigment system allows for heightened contrast
detection to enhance differentiation between radiance characteristics
of the carapace or secretory luminescence and that of background
light. proposed
that the deeper-living oplophorid genera have abandoned a dual
system in favor of a single visual-pigment system, which may
allow for increased light sensitivity in deeper waters where light
is more limited