OBSERVATIONS ON THE RESPIRATION OF THE SABELLID POLYCHAETE SCHIZOBRANCHIA INSIGNIS

Abstract

1. Observations on the life of a sabellid Schizobranchia insignis have been made under conditions resembling as far as possible those found in nature. 2. The amount of time spent with the crown expanded and the amount passed wholly withdrawn within the tube have been measured, and the utilisation of oxygen under these two conditions estimated. 3. The volume of water passed through the crown for respiratory and feeding purposes, as well as the volume pumped through the tube, have also been measured, and the part played by each in respiratory exchange discussed. It was found that about 70 ml./hr./g. animal (fresh weight) is passed through the crown by the action of the filamentary cilia, and the volume pumped through the tube is about 12 ml./hr./g. 4. Utilisation of oxygen by the crown is relatively low (10%); utilisation by the whole worm when withdrawn is about 24%, and the large volume strained by the crown is probably related to the food requirements rather than to the respiratory needs of the worm. 5. It is suggested that the oxygen taken up by the crown is largely utilised in its own activity although it can, and does, provide for the needs of the rest of the body during pauses in irrigation when expanded.