BLUE-RAYED LIMPET
A maximum of two centimetres long and mostly khaki coloured, blue-rayed limpets (Patella pellucida) have one attention grabbing feature: electric blue stripes. This striking colour is carefully constructed. Blue-rayed limpets create their stripes as they grow by ordering calcium carbonate into bands of structure that reflect blue light against a background of contrasting light absorbing particles. Juvenile limpets are plain and then become spotted with blue. As their size increases so does the length of their blue patches, turning them from polka dots into stripes – unless they are the laevis form of blue-rayed limpet that lives within the holdfasts of kelp. While pellucida morphs have blue stripes and live an exposed life on kelp fronds and stalks, laevis morphs are concealed and have no bright stripes. Blue-rayed limpets use stripes for visual communication.