open access

https://doi.org/10.14943/bull.fish.74.1.1

https://hdl.handle.net/2115/92921

Function of Bubble for Recovery from Cryptobiosis in Tardigrade Milnesium tardigradum

日本語

Recovery

2024-08-04

Faculty of Fisheries Sciences, Hokkaido University

Bulletin of Fisheries Sciences, Hokkaido University

74(1)

1-11

Tardigrades enter a cryptobiotic state (barrel-shaped form) to persist in extreme environments, but there are few experimental observations to examine how complete recovery from this state occurs. Here, we directly observed the tardigrade Milnesium tardigradum in the cryptobiotic and active states under the microscope with a video system. Rates of complete recovery of cryptobiotic organisms with or without cover glasses were 71.4% and 73.3%, respectively, suggesting no effect of the cover glass on the recovery success in this species. More than 50% of organisms showed bubbles in the mouth canal during the recovery process regardless of the recovery success. Since these bubbles disappeared just before the recovery at the end of the mouth canal, but did not flow into the pharynx, bubbles might flow into the body cavity and regulate the intracorporeal pressure during recovery. Bubbles were also observed in the mouth canal of active organisms entering the cryptobiotic state. Bubbles therefore occurred in both cryptobiotic-to-recovery and active-to-cryptobiotic processes. The end of the mouth canal in M. tardigradum might function as a barrier between the external and internal environment and contribute to the regulation of hydrostatic pressure in the body cavity.

紀要論文

Version of Record

2435-3353

AA12019704