Human skin color the liver. On lighter to medium skin tones, solar lentigenes emerge as small- to medium-sized brown patches of freckling that can grow and accumulate over time on areas of the body that receive the most unprotected sun exposure, such as the back of the hands, forearms, chest, and face. For those with darker skin colors, these discolorations can appear as patches or areas of ashen-gray skin. Melanin in the skin protects the body by absorbing solar radiation. In general, the more melanin there is in the skin the more solar radiation can be absorbed. Excessive solar radiation causes direct and
Accessory pigment overall trend for water to absorb low frequencies, while gilvin and tripton absorb higher ones. This is why open ocean appears blue and supports yellow species such as "Prochlorococcus", which contains divinyl-chlorophyll "a" and "b". "Synechococcus", colored red with phycoerythrin, is adapted to coastal bodies, while phycocyanin allows Cyanobacteria to thrive in darker inland waters. Accessory pigment Accessory pigments are light-absorbing compounds, found in photosynthetic organisms, that work in conjunction with chlorophyll "a". They include other forms of this pigment, such as chlorophyll "b" in green algal and higher plant antennae, while other algae may contain chlorophyll "c" or "d".