COMPARATIVE STUDIES OF THE PIGMENTS OF SOME PACIFIC COAST ECHINODERMS

Abstract

1. The pigments of echinoderms, belonging to twelve species, nine genera and four classes, have been studied qualitatively and in part quantitatively, with the aid of certain standard methods.2. Carnivorous species contained more carotenoids in the aggregate than did herbivores, by some three or four-fold.3. Among the echinoids, endrastenrand Lytechinus males yielded more total carotenoids than did females, while in Strongylocentrotus purpuratus, the concentrations in each sex were similar. Females of Strongylocentrotus and Lytechinus contained about a fourth of their carotenoids in the ovaries, whereas corresponding males mobilized about one-sixth and three-quarters, respectively, to their testes.4. Oxygenated carotenoids, including xanthophylls and acidic compounds, preponderated vastly over the hydrocarbon type (carotenes) in carnivores, while in most herbivores epiphasic pigments, including carotenes and echinenone, showed some degree of predominance.5. The presence of the ketonic carotenoid echinenone was indicated in most of the echinoids; its presence was also regarded as likely in another member of the herbivore-omnivore group, i.e., the cucumber Stichopus, and in one carnivore, Astropecten.6. Carotenoid acids, or compounds which yield carotenoid acids on treatment with alkali, were found only in carnivorous species. A new type of epiphasic pigment, with a single absorption maximum in the violet at values of from 460 to 475 mµ, yielding an acid on hydrolysis, was found in the ophiuroids.7. Xanthophyll esters were found consistently in the Ophiuroidea and in one of the Asteroidea, Pisaster giganteus. In the ophiuroids, they were of the heavily oxygenated type, and replaced carotenes, which were completely lacking. One of three catches of Strongylocentrotus purpuratus yielded some esterified lutein-like xanthophyll.8. The occurrence of echinochromes, found only in the echinoids, and of green pigments, "enterochlorophylls," found in the intestines of carnivores, is discussed.