Ultrastructural observations on feeding appendages and gills of Alvinella pompejana (Annelida, Polychaeta)

Abstract

The feeding appendages of Alvinella pompejana obtained from a deep-sea hydrothermal vent environment are described. They are characterized by a ciliated groove, the cells of which have a very distinctive ultrastructure, by groups of bipolar receptor cells and by several kinds of gland cells. Among these, one cell type is in an upside down position suggesting a function completely different from other epidermal secretory cells. The gills differ considerably from the feeding appendages on the basis of their ultrastructure. Their epidermis is very irregular in height; basal infoldings give the blood access to a space coming very near to the external medium. The blood vascular system is open. On the other hand, the gills of Amphicteis gunneri are not effective sites of gas exchange, since their columnar epithelium is underlain with muscle cells. The cells composing the feeding appendages and gills of Alvinella pompejana are characterized by ultrastructurally very different mitochondria. © 1986 Biologische Anstalt Helgoland.