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Temperature Experiment
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Study Citation
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Persson, D., Halberg, K. A., Jørgensen, A., Ricci, C., Møbjerg, N., & Kristensen, R. M. (2011). Extreme stress tolerance in tardigrades: surviving space conditions in low earth orbit. Journal of Zoological Systematics and Evolutionary Research, 49, 90-97. [link]
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Methods
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In a lab experiment, tardigrades (species Richtersius coronifer) were submerged in liquid nitrogen (-196 °C, -320 °F) for 20 hours, which instantly freezes them solid. After 2 hours in liquid nitrogen, they were thawed at room temperature for 2 hours. This experiment was performed on active and dessicated ("tun" state) tardigrades. After the experiment, the experimental (exposed to liquid nitrogen) and control (not frozen) groups of tardigrades were returned to their normal care. Every few days, scientists counted how many tardigrades from each group were still alive. They tracked their survival until all the tardigrades had died.
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Data & Instructions
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The data table below shows the percent of tardigrades that survived were still alive being exposed to liquid nitrogen (-196 °C, -320 °F) for 20 hours. Survival was measured immediately after exposure up to 140 days after exposure. Results are shown for the experimental tardigrades (tun and active states) and the control group (not frozen) for comparison.

Make a graph that shows tardigrade survival (%) as a function of time after exposure (days) for all three groups. Did exposure to flash freezing impact the lifespan of the tardigrades? Did the tun state vs. active state make a difference in survival? Yes, the tun state (cryptobiotic) tardigrades had higher survival relative to the active tardigrades. Ultimately, both the tun-state and active experimental tardigrades all perished about 2 months before all the control tardigrades perished.

What is the average temperature on the surface of the moon? How long have the tardigrades been exposed to these conditions? Do you think the tardigrades could survive the temperatures on the moon? Explain your reasoning. Moon surface temps: Night -300 °F(-180 °C), Day +225 °F(105 °C). The moon experiences large temperature swings because there is no atmosphere to trap and distribute heat.


For reference, humans can only survive with an internal body temperature as low as 13.7 °C (56.7 °F).
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Percent (%) Survived
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Days after exposureExperimental Group (tun state)Experimental Group (Active)Control Group
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099%30%100%
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1095%10%98%
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4055%10%65%
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5020%8%35%
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634%3%33%
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803%0%17%
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900%0%12%
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1150%0%5%
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1400%0%0%
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