The existence of a symbiotic association between vestimentiferan tube worms from deep-sea hydrothermal vents and chemoautotrophic sulfur-oxidizing prokaryotes, based on histological and enzymatic evidence, is suggested.

No abstract

Pogonophora, also known as Siboglinidae, are tube-dwelling marine annelids. They rely on endosymbiotic chemoautotrophic bacteria for nutrition and their anatomy and physiology are adapted to their need to obtain both oxygen and reduced sulphur compounds. Frenulate pogonophores are generally long and slender, sediment-living tubeworms; vestimentiferans are stouter, inhabitants of hydrothermal vents and cool seeps; and moniliferans or sclerolinids are very slender inhabitants of decaying wood and sulphidic sediments. The anatomy and ultrastructure of the three groups are compared and recent publications are reviewed. Annelid characters are the presence of chaetae and septa, concentrated at the hind end. The adaptations to a specialised way of life include, in particular, the chitinous tube; the anterior appendages that function as gills; the internal tissue called the trophosome, where the endosymbiotic bacteria live; and the blood vascular system that transports oxygen, sulphide and carbon dioxide to the trophosome.

On the Early Development of the Vestimentiferan Tube Worm Ridgeia sp. and Observations on the Nervous System and Trophosome of Ridgeia sp.

No abstract

No abstract

Rudimentary cilia have been observed in muscle cells lining the tube feet of Ophioderma brevispinum (Ophiuroidea) and in muscle cells of the body wall and parapodial glands of Owena fusiformis (Polychaeta). A diplosomal basal body is associated with each cilium. Striated rootlets are absent. This is the first report on rudimentary cilia in muscle cells of an echinoderm and an annelid.

No abstract