The metabolism of carotenoids and their subsequent contribution to coloration in the marine isopod, Sphaeroma quadridentatum

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I investigated the metabolism of carotenoids, the contributions of carotenoids to body color and the population dynamics in the marine isopod, Sphaeroma quadridentaturn. Morphometric measurements, the types and the concentrations of carotenoids present in whole animal extracts were determined for isopods during growth and maturation, reproduction and also during periods when habitat conditions were changing. Isopods were collected at a Galveston, Texas beachfront site at approximately monthly intervals from March, 1979 through March, 1980. The Texas beachfront population studied had a higher growth rate and a shorter life span than that reported for European sphaeromid species. Temporal variation in monthly mean length was due to the release of brooded young, the death of adults and the growth of juveniles. Beachfront populations may experience two reproductive periods per year, however multiple clutches may be prevented by stringent environmental conditions. Coloration in this species was due to two biochemical components: carotenoids uniformly dispersed through the dermis and cuticle and melanophore pigments in dermal Chromatophores. Body color ranged from yellow to dark grey and was determined by the degree of melanophore pigment dispersion. Melanophore pigments undergo diurnal rhythmic dispersion and pigment dispersion was determined primarily by the ratio of incident to reflected light intensity. [...]

Carotenoids--Metabolism, Crustacea