The mantis shrimps are the only animal species known to science that can
recognize circularly polarized light (CPL). Here we explored the
morphological and molecular mechanisms of CPL recognition in
Oratosquilla oratoria, a typical species of mantis shrimps.
Through multilayer microscopy, we discovered the cross-arranged
microvilli and the oval distal rhabdom to be the critical structures for
CPL recognition. Based on the specific expression patterns of
vision-related functional genes and proteins, we suggest that the order
of light utilization by O. oratoria compound eye was first
natural light, then left-rotation CPL (LCPL), linearly polarized light,
right-rotation CPL (RCPL) and dark. Meanwhile, we found that the
expression levels of vision-related functional genes and proteins in
O. oratoria compound eye under RCPL were not significantly
different from those in DL, and thus provide additional evidence that
mantis shrimp can only recognize LCPL. Furthermore, the recognition of
LCPL is likely facilitated by the differential expression of opsin and
microvilli - related functional genes and proteins (arrestin and
sodium-coupled neutral amino acid transporter). In conclusion, this
study systematically illustrated for the first time how O.
oratoria compound eye recognizes CPL, and it can improve the visual
ecological theory behind polarized light recognition.