Effects of Microgravity on Aurelia Ephyra Behavior and Development

Developmental biology

Aurelia aurita (jellyfish)
Flight: 36

Synchronous

Ambient Temperature Recorder, Biorack (provided by ESA), Biorack Type I Containers (provided by ESA), Nizemi (provided by DLR), Refrigerator/Incubator Module

Aurelia polyps and ephyrae were exposed to microgravity and 1 G controls (inflight and ground) in order to compare, while in flight, the swimming behavior of ephyrae that developed in microgravity with the controls. Centrifugation of the ephyrae at different G-levels on the Nizemi microscope was used to establish the G-threshold for Earth-type behavior. Numbers of buds per polyp maintained in microgravity for 14 days were compared pre- and postflight with ground controls. The rate of metamorphosis during ephyra development was also determined in space and at 1 G. Immediately postflight, the morphology and the swimming/pulsing behavior of the ephyrae that had developed in microgravity were recorded and compared with ground controls.

Polyps were induced to metamorphose at L-24h preflight with iodine at 22 °C. These polyps as well as ephyrae were maintained in the Biorack when they were not being exposed to graded levels of gravity on the Nizemi. These organisms and metamorphosing jellyfish were videotaped at different intervals throughout the mission, as were ground controls. Postflight, ephyrae were videotaped, photographed, and examined microscopically in order to record swimming activity and to count the number of pulses, arms, and statoliths per animal.

Ephyrae that developed in microgravity had significantly more abnormal arm numbers as compared with 1 G controls in space and on Earth. Their mean numbers of statoliths, rhopalia, and pulses per minute as determined postflight did not differ significantly from controls nor did their types of pulsing abnormalities. Significantly fewer ephyrae that developed in space swam when tested postflight than did the controls. Polyps budding in space produced more buds and were developmentally ahead of ground controls. The G-threshold studies of ephyrae sent into space from Earth revealed that more than 50% of the ephyrae convert to Earth-like swimming behavior upon exposure to 0.3 G. Although development through budding and through metamorphosis proceeds well in space, some jellyfish are apparently more sensitive to the microgravity environment than others, as evidenced by their abnormal arm development.

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Spangenberg, D. et al.: Effects of Weightlessness on Aurelia Budding and Ephyra Development (abstract). American Society for Gravitational and Space Biology Bulletin, vol. 9(1), Oct 1995, p. 88.

Spangenberg, D.B. et al.: Hair Cell and Statocyst Differentiation in Aurelia Ephyrae Which Developed in Microgravity. American Society for Gravitational and Space Biology Bulletin, vol. 10(1), 1996, p. 34.

Spangenberg, D.B. et al.: Touch-Plate and Statolith Formation in Graviceptors of Ephyrae Which Developed While Weightless in Space. Scanning Microscopy, vol. 10(3), 1996, pp. 875–888.

Spangenberg, D.B. et al.: Effects of Weightlessness on Aurelia Budding and Ephyra Development. Proceedings of the Sixth International Conference on Coelenterate Biology, Noordwijkerhout, the Netherlands, Nationaal Natuurhistorisch Museum, Leiden, 1997, pp. 447–453.