Chromatophores: The large pigment cells of fish, amphibia, reptiles and many invertebrates which actively disperse and aggregate their pigment granules. These cells include MELANOPHORES, erythrophores, xanthophores, leucophores and iridiophores. (In algae, chromatophores refer to CHLOROPLASTS. In phototrophic bacteria chromatophores refer to membranous organelles (BACTERIAL CHROMATOPHORES).)Bacterial Chromatophores: Organelles of phototrophic bacteria which contain photosynthetic pigments and which are formed from an invagination of the cytoplasmic membrane.Rhodospirillum rubrum: Vibrio- to spiral-shaped phototrophic bacteria found in stagnant water and mud exposed to light.Rhodospirillum: A genus of gram-negative, spiral bacteria that possesses internal photosynthetic membranes. Its organisms divide by binary fission, are motile by means of polar flagella, and are found in aquatic environments.Bacteriochlorophylls: Pyrrole containing pigments found in photosynthetic bacteria.Rhodopseudomonas: A genus of gram-negative, rod-shaped, phototrophic bacteria found in aquatic environments. Internal photosynthetic membranes are present as lamellae underlying the cytoplasmic membrane.Photophosphorylation: The use of light to convert ADP to ATP without the concomitant reduction of dioxygen to water as occurs during OXIDATIVE PHOSPHORYLATION in MITOCHONDRIA.Rhodobacter sphaeroides: Spherical phototrophic bacteria found in mud and stagnant water exposed to light.Sepia: A genus of cuttlefish in the family Sepiidae. They live in tropical, subtropical and temperate waters in most oceans.Chromatium: A genus of gram-negative, ovoid to rod-shaped bacteria that is phototrophic. All species use ammonia as a nitrogen source. Some strains are found only in sulfide-containing freshwater habitats exposed to light while others may occur in marine, estuarine, and freshwater environments.Melanophores: Chromatophores (large pigment cells of fish, amphibia, reptiles and many invertebrates) which contain melanin. Short term color changes are brought about by an active redistribution of the melanophores pigment containing organelles (MELANOSOMES). Mammals do not have melanophores; however they have retained smaller pigment cells known as MELANOCYTES.Animal Fins: Membranous appendage of fish and other aquatic organisms used for locomotion or balance.Pigmentation: Coloration or discoloration of a part by a pigment.Rhodobacter capsulatus: Non-pathogenic ovoid to rod-shaped bacteria that are widely distributed and found in fresh water as well as marine and hypersaline habitats.