Mol Ecol. 2014 Jun;23(11):2740-56. doi:10.1111/mec.12781

Mojib N, Amad M, Thimma M, Aldanondo N, Kumaran M, Irigoien X.

Carotenoid metabolic profiling and transcriptome-genome mining reveal functional equivalence among blue-pigmented copepods and appendicularia.

Mass spectrometry shows that astaxanthin is the main carotenoid pigment in O. dioica. β‐carotene is probably taken from the food chain. Two cytochrome P450 β‐carotene hydroxylase genes were identified (CBY21750 and CBY13480) and may be involved in the conversion to astaxanthin. Three carotenoid‐binding proteins from the lipocalin family were found in the genome, and may be implicated in providing blue color by binding to astaxanthin.