PRINCIPAL INVESTIGATOR(S ) : R. J. von Baumgarten, Richard C. Simmonds, John F. 



Boyd, and Owen K. Garriott 



EXPERIMENT TITLE/NUMBER : Effects of Prolonged Weightlessness on the Swimming 



Pattern of Fish Aboard Sky lab 3, SD10 



PROGRAM/ MISSION : Skylab 3 



CLASSIFICATION : Animal -' Killifish (Fundulus heteroclitus ) 



DISCIPLINE(S) : Behavioral science, Neurosensory 



OBJECTIVES : To determine whether the vestibular behavior of fish would show 

 any disburbance during the first few days in space, whether the peculiar 

 "looping behavior" of fish observed during parabolic flight would continue 

 during prolonged spaceflight, and whether fish embryos would develop, hatch, 

 and swim normally in weightlessness. 



PROTOCOL : Two sighted fingerling fish and 50 embryonated fish eggs were flown 

 in a polyethylene "aquarium." The bag containing the fish and eggs was sealed 

 in a tin can at 1 atm pressure. A duplicate bag of fish and eggs served as a 

 ground control. Inflight, the can was opened and the bag taped to a wall for 

 observation with pictures being taken on days 3 and 21. The eggs were 

 fertilized at F-96 hrs. 



EQUIPMENT : Polyethylene bag, transport canister, photgraphic equipment 



RESULTS : The two fingerlings swam in tight circles inflight, looping sideways 

 most of the time, with their backs directed towards the light source. The 

 frequency of the looping episodes diminished slowly after the third day until 

 normal swimming was prevalent. Development of embryonic stages (32, 66, 128, 

 216, 336h) continued inflight. Microscopy of fry and hatchling showed CNS, 

 cardiovascular, optic, vestibular systems normal. Juvenile swimming pattern 

 postflight suggested abnormal swim bladders. 



CONCLUSIONS : Weightlessness acts as a permanent vestibular stimulus until 

 long-term habituation occurs. This appears to be the result of a central 

 active inhibitory process and not of fatigue or receptor adaptation alone. 

 The swimming anomaly could be due to (1) absence of continuous bending of 

 sense hairs to a certain extent by gravity, causing the fish to tilt forward 

 in an attempt to increase leverage on the hairs; or (2) an attempt by the fish 

 to create a gravitoinertial stimulus by "centrifuging" its otoliths by 

 looping. 



PUBLICATIONS : 471, 544 



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