Emerging Field of Tardigrades and their Stress Tolerance

A couple of years ago, Japanese scientists thawed a frozen moss sample from Antarctica collected 30 years earlier. They observed two minute creatures crawling back to life from three decades of 'cryo-sleep' inside the moss sample. These tiny time-travellers were tardigrades, also known as water bears. They have four pairs of legs and their body size is about 0.3-1 mm (Figure 1). There are more than thousand species of tardigrades which thrive in freshwater, marine and limno-terrestrial environments. Though most of them have an extraordinary ability to resist desiccation, they need water to grow and reproduce. Some tardigrades are herbivores and feed on algae, while carnivorous species feed on rotifers, nematodes and even smaller tardigrades.