To evaluate the relative importance of tentacular crown and body surface in sabellid respiration, experiments were carried out on Eudistylia vancouveri (Kinberg, 1867), a long narrow worm living in a permanent tube in the intertidal zone. This species irrigates its tube by peristaltic waves, as do most species of Sabellinae and this allows water circulation inside the tube for body surface respiration.

Measurements of oxygen uptake after amputation of the tentacular crown indicated a reduction of about 80% of the total respiration. This value was higher than that found for other Sabellinae studied. Some predictions about other species were made on the basis of the present observations and of comparison with species having similar aptitudes.

The habit of living in a narrow tube protruding from the sea bottom, as occurs among sabellids, implies some adaptations concerning feeding, excretion and respiration. In the order Sabellida, the prostomium is reduced and fused to the peristomium which usually forms a large tentacular crown (Fauchald, 1977) with both feeding and respiratory functions. Its relative importance in respiration, however, is still little known. Survival after crown amputation suggests that this structure is not essential for respiration; moreover some species can autotomize and regenerate it (Berrill, 1931; Okada, 1934). In sabellids, respiration can in fact occur at the level of the body surface and this is made possible by the flux of the water contained in the tube which is generated by the worm itself: i.e. irrigation. Sabellinae species can actively irrigate their tubes by waves of muscular contraction of the body wall in either direction.