This is not, sensu stricto, a post about aging, but what can I say? Tardigrades! I love these little guys. Plus it’s Friday.
Last year we learned that organisms of the phylum Tardigrada (the so-called “water bears,” most closely related to arthropods) are unusually resistant to physiological stress. Given the well-established relationship between long lifespans and resistance to (most) stresses, I had wondered why tardigrades are not also unusually long-lived. (They can persist for years in a dormant state, but their fully animated lifespans are on the order of months.)
Now, Jönsson et al. reveals that tardigrades can survive unshielded in outer space:
Tardigrades survive exposure to space in low Earth orbit
Vacuum (imposing extreme dehydration) and solar/galactic cosmic radiation prevent survival of most organisms in space. Only anhydrobiotic organisms, which have evolved adaptations to survive more or less complete desiccation, have a potential to survive space vacuum, and few organisms can stand the unfiltered solar radiation in space. Tardigrades, commonly known as water-bears, are among the most desiccation and radiation-tolerant animals and have been shown to survive extreme levels of ionizing radiation. Here, we show that tardigrades are also able to survive space vacuum without loss in survival, and that some specimens even recovered after combined exposure to space vacuum and solar radiation. These results add the first animal to the exclusive and short list of organisms that have survived such exposure.
Which is pretty cool, when you think about it.
Still, as an adherent of the “stress resistance = longevity” school, I am nagged by the question: If tardigrades can survive hard vacuum, ultra-low temperatures, blazing radiation and Klingon disruptors, what on Earth (or off it, for that matter) is going on inside their cells that does them in after a few short months of life?