OXYGEN POISONING IN THE ANNELID TUBIFEX TUBIFEX I. RESPONSE TO OXYGEN EXPOSURE

¹ Department of Physiology and Biophysics, University of Illinois, Urbana, Illinois 81801

1. Exposure to hyperbaric oxygen caused T. tubifex to become hyperactive. After high doses of oxygen the worms became highly coiled and contracted and showed little movement. The behavioral response to oxygen exposure became complete only after several hours when the animals either disintegrated or began to resume normal behavior.

2. Exposure to four atmospheres absolute oxygen pressure for 13 to 15 hours caused high mortality of T. tubifex. Only an occasional worm survived. Exposure to four atmospheres absolute oxygen pressure for nine to 12 hours killed approximately half of the treated animals. Exposure to four atmospheres absolute oxygen pressure for eight hours or less caused no greater mortality than in unexposed controls.

3. The lethal effects of oxygen exposure developed only after several hours. The lethal effect of a nine- to 12-hour exposure was half maximal in 24 hours and the effect of a 13- to 15-hour exposure in six hours. Some lethally-exposed worms survived for as long as 120 hours after 13- to 15-hour oxygen exposures.

4. Exposure to three atmospheres nitrogen added to one atmosphere of air for as long as 30 hours resulted in no more deaths than in unexposed controls and caused no change in worm behavior.

5. Interruption of a 16-hour oxygen exposure with return to atmospheric conditions enhanced survival of oxygen-treated T. tubifex. Increased duration of interruption led to increased survival of oxygen-treated worms. Recovery was half maximal in four hours and maximal in approximately 16 hours.

6. Adaptation to hyperbaric oxygen occurs in T. tubifex following several weeks of exposure to atmospheric oxygen tensions in shallow containers without a protective mud environment.