Red Coloration in an Anchialine Shrimp: Carotenoids, Genetic Variation, and Candidate Genes.

Red coloration is a widely distributed phenotype among animals, yet the pigmentary and genetic bases for this phenotype have been described in relatively few taxa. Here we show that the Hawaiian endemic anchialine shrimp is red because of the accumulation of astaxanthin. Laboratory colonies of phylogenetically distinct lineages of have colony-specific amounts of astaxanthin that are developmentally, and likely genetically, fixed.