New complex communities of morphologically diverse and sometimes abundant large, multicellular, filamentous
bacteria were discovered in the oxygen-deficient, organically laden, shelf sediments under the oxygen minimum zone off the coast of the eastern Pacific, i.e., off the coasts of central and northern Chile; central and northern Perú; Roca Redonda, Galápagos Archipielago, Ecuador; and off the Pacific coasts of Panamá and Costa Rica. Similar microbial communities were also observed in the reduced layer of a muddy-sand beach adjacent to a mangrove swamp on Coiba Island, Pacific Panamá, and in the organically laden bottom underneath a salmon culture pen in southern Chile (region X). Of varying morphology, the diameters of the bacteria range fro
