Abstract
Astaxanthin is the dominant carotenoid pigment found in the marine copepod, Tigriopus californicus (Baker), giving these animals orange-red coloration. Like all metazoans, T. californicus must convert carotene or hydroxy-carotenoids present in their algal diet to astaxanthin. Other astaxanthin-pigmented crustaceans have been shown to use a precursor-specific bioconversion pathway to astaxanthin. The aims of this study were to demonstrate that californicus bioconverts dietary carotenoids to astaxanthin. Prior to the experiments copepods were maintained on a carotenoid-free diet on which they lost all carotenoid coloration. Copepods were then fed one of four dietary carotenoids (β-carotene, lutein, zeaxanthin, or canthaxathin) that are precursors to specific astaxanthin bioconversion pathways. We found that copepods from each precursor pigment group produced astaxanthin, and that the amount produced depended on which carotenoid was supplemented. We also describe the distribution of astaxanthin in developing egg sacs and show that the red color of the naupliar eyespot is not due to astaxanthin.