An aeolid nudibranch displays its rows of cerata, respiratory organs, down its back. Each ceras is tipped with a stinging "cnidosac" used for the nudibranch's protection. The stinging cells (and the orange-brown color) come from the nudibranch's food, hydroids and other stinging cnidarians. Therefore, individuals of the same species can vary greatly in color depending on the food source.
Nudibranch - Pteraeolidia ianthina, taken at Mwahnd Pass/Palikir Pass, Pohnpei, MIcronesia
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