CHAPTER ONE

DRY HARD

Water

Let’s begin with our poster child of life’s resilience: the tardigrade. What makes them so invulnerable, so resilient, almost impossible to kill? How can they survive such a variety of lethal influences, from radiation to pressure, burning heat to freezing cold? The answer lies in their ability to live without that most precious resource of life, the sole search image for extraterrestrials used by NASA: water. Desiccation, it seems, is the greatest tonic against death.

The day after I had met Ellis Moloney in Plymouth, the rain still pouring down, I went looking for these animals in their natural environment. I was walking our dog Bernie along the coastal path near our home, a low-hanging grey sky closed in all around us. In sheltered coves, a barrage of white-tipped waves crashed on the rocks below. As we turned back, away from the coast, the sound of the sea was replaced by the roar of trees blowing in the wind. Soaking wet, I saw some thick pads of moss on an old dry stone wall, and decided this was the ideal place to find them. I scraped a few clumps with my fingernail, the rootless plants easily coming off like orange peel, and placed them in a clean poo bag. Although any tardigrades I had collected would be clinging to the moss with their tiny claws, I tied the bag with a loose knot to prevent any escapees.

Back home, changing out of my sodden shoes and clothes, I poured some tap water over the top and used some coffee filter paper to remove most of the excess water. What was left was a layer of soil, a few fronds of moss and, I hoped, a healthy population of water bears.

This wasn’t my first foray in moss collecting. I had already bought a second-hand digital microscope – the kind that is often used when fixing broken electrical boards – to peer into the microcosmos surrounding my home. With a magnification of 40 times, it was perfect for spotting animals less than a millimetre long. But, alas, I had no luck finding water bears.

This time, however, my eyes had been trained to Moloney’s lab-reared tardigrades. I knew the general shape, the way they moved, and focused on places that they could cling to. Under the microscope, what looked like a thin layer of brown soil to the naked eye was transformed into discrete particles of sand. Brown was actually a range of hues from a pale blond to almost black. There were tiny fragments of moss and – there, yes there! – a small, transparent tube scrambling between the grains. At such low magnification, I couldn’t see the finer details of this animal – it’s pinprick eye, its eight chubby legs with claws at each end, the protrusible stylet that it uses to suck out the innards of algal cells. On my computer screen, I watched the blurry image and escaped the here and now for a few minutes. Obse