Ctenophores or commonly known as comb jellies have a unique physiology that allows them to refract light which is why they shine a rainbow of colors. Even without sunlight, these jellyfish are still colorful just less vivid. 
Photo: Jason Edwards, National Geographic   
 

Ctenophores or commonly known as comb jellies have a unique physiology that allows them to refract light which is why they shine a rainbow of colors. Even without sunlight, these jellyfish are still colorful just less vivid. 

Photo: Jason Edwards, National Geographic