Nudibranch Displays A Stunning Set Of Colors:

This Nudibranch Displays A Stunning Set Of Colors: 

The body is purple, the cerata are orange and the rhinophores are scarlet. 

The neon orange appendages on the back of Flabellina iodinea are the cerata which extract oxygen from the sea water they live in.

The cerata are also extensions of the digestive system, and are used to store the stinging cells of the anemones and fan-like hydroids they eat. 

The red rhinophores are sensory structures used for detecting the presence of possible mates and prey. The purple, red, and orange colors are derived from a single carotenoid pigment, astaxanthin.

The pigment appears in three modified states, leading to the three distinct colors.

Scientists guess the reason why the Spanish Shawl's gills are orange is so they can camouflage with their prey while they are eating.

. 

The orange gills on their backs are also a warning to potential predators. The color tells their predators that they are either poisonous or distasteful.