15 seconds. If you were thrust into outer space without any protection, you could achieve, mercifully, death within 15 seconds. In these 15 seconds, your mere mortal flesh would burst like a balloon as your lungs inflated, your blood boiled, and the very DNA that once defined you ruptured from radiation.
Now there is one creature that is capable of surviving in the same conditions that would utterly destroy a human. Its mouth lined with sharp daggers, this beast navigates the void of outer space, the bitter cold of absolute zero, and the fury of temperatures exceeding 300ºF. It predates, and will outlive, humanity, with roots tracing back over 500 million years and a formidable resilience that will ensure many millennia to follow.
And of course, at only 1/16 of an inch in length, it is one of nature’s smallest animals.
Enter the tardigrade. Endearingly known as the water bear or even the moss piglet, the tardigrade is resistant to the same adverse conditions that would cripple humans. It owes its strength to cryptobiosis, during which its metabolic processes can be brought to a halt. During cryptobiosis, the tardigrade retains only 3% of its original water content, becoming a lifeless husk that can remain dormant for years and reanimate with a drop of water. In terms of withstanding extreme temperatures, our dear piglets synthesize a sugar called trehalose that actually forms a glass-like protective seal to prevent damage to essential proteins and membranes. Trehalose glass also prevents the expansion of membranes and molecules that would otherwise obliterate the tardigrade from within, as it would do to us frail humans.
Now why would an organism that spends so much time leisurely exploring moss and lichen in a state of suspended reality need the powers it possesses? Tardigrades require a thin layer of water around their bodies to move, eat, and simply to function. As the majority of tardigrades dwell in terrestrial environments susceptible to sudden change, it’s hardly a shock that they developed a mechanism for sudden dehydration (1).
Stunned by the tardigrade’s resilience, Ingemar Jonsson from Kristianstad University thought it appropriate to put what looked like a monster out of Doctor Who on the TARDIS. That is, the Tardigrades In Space mission of 2008. Jonsson’s report demonstrated that in the vacuum of space, the water bears were not only able to survive, but also reproduce and thrive even when exposed to the full spectrum of UV radiation, up to 500 times what a sunbather could expect to soak up.
More recently, researchers at the University of Chicago looked to the tardigrade for inspiration to explain the mysteries of glass and its structure. Professor Juan de Pablo’s interest was piqued when he examined the ability of the water bears to coat themselves with trehalose glass to remain in a state of suspended animation in conditions of extreme dehydration, heat, or cold. Published this past spring, his research counteracts prior belief that glass has a relatively disordered structure by indicating that the tardigrade’s trehalose glass “can exhibit high levels of molecular orientation.” A bewildered de Pablo states, “Randomness is almost the defining feature of glasses. At least we used to think so. What we have done is to demonstrate that one can create glasses where there is some well-defined organization.” Thanks to the miniscule tardigrade, the professor was able to conclude that trehalose glass’s high levels of orientation and thermal stability give it the potential to improve the efficiency of light-emitting diodes, solar cells, and even our own cellular health.
While it’s doubtful we’ll see humans floating about in states of suspended reality any time soon, the tardigrade has inspired scientists like Dr. John Crowe of UC Davis to apply cryptobiosis to saving lives. Considering the impact trehalose glass has on preserving the tardigrade’s cells, Dr. Crowe asked if trehalose could also be used to protect human cells from damage when they were dried. Hoping to save soldiers from bleeding to death on the battlefield, the US military turned to his research that extended the life of blood platelets from a mere five days to up to two years.
Tardigrades are omnipresent on earth, allowing even you and I to adopt one of the roughest, toughest little pets on eight legs. Despite their ability take the bleakest of conditions by storm, tardigrades are far from extremophiles, and prefer a habitat of moss and lichen. Thus, if you collect a clump of moss or lichen and soak it in water in a petri dish for about 5 hours, after draining the water, you’ll be able to see the tardigrades paddling around in their signature suspended reality (2).
What do you see when you look at a tardigrade… the potential for space exploration in suspended reality, an opportunity to redefine our understanding of glass, or perhaps just an adorable little moss piglet? Regardless of what you see, or hope to, much of what we have discovered about tardigrades is rooted in the undying resilience they bring to everyday life. Whether they’re traversing new frontiers in the desolation of outer space, waddling carelessly in absolute zero or absolutely blazing temperatures, or lazing around in their native moss and lichen, tardigrades have been here for over 500 million years. And with their formidable resilience, they don’t plan on leaving any time soon. ✦
1. Dean, Cornelia. “The Tardigrade: Practically Invisible, Indestructible ‘Water Bears’.” The New York Times. The New York Times, 7 Sept. 2015. Web. 12 Oct. 2015. <http://www.nytimes.com/2015/09/08/science/the-tardigrade-water-bear.html?_r=1>.
2. Bordenstein, Sarah. “Tardigrades.” Microbial Life Educational Resources. Carleton College. Web. 1 Nov. 2015. <http://serc.carleton.edu/microbelife/topics/tardigrade/index.html>.