Astaxanthin is a reddish-orange carotenoid and xanthophyll pigment common in the natural environment. Many animals derive their distinctive coloring from astaxanthin - salmon, shrimp, krill, lobster, and flamingoes. Animals cannot make carotenoids, so they must obtain them from plants, bacteria, and algae. That many forms of life retain and concentrate astaxanthin in their tissues suggests it is somehow useful.
