The hardiest bear that never was

Just over a month ago I visited the American Museum of Natural History in New York City. There I was fascinated with the phylogenetically accurate layout of fossils over the museum floorspace, showing the evolution of fish to amphibians, and then to reptiles (no Tiktaalik unfortunately) for example. During my visit I was also enraptured by an exhibition entitled; Life at the limits: Stories of Amazing Species, as one particular species stood out to me as the star of the survival show.
What if I told you there is a species of 'bear' that has existed on earth since the Cambrian period, around 500 million years ago? The word delusional would most probably spring to your mind, however I have evidence from the fossil record. Perhaps the word 'bear' was disconcerting, as I did not mean a member of the Ursidae family, but in fact a species known as the Tardigrade (me and my science word plays...). The Tardigrades have nicknames such as Water Bears or Moss Piglets, perhaps due to physical appearance (I don't see it personally, but they are kinda pudgy) and their favoured habitats; films of water that cling to mosses. Tardigrades are a large group of animals, consisting of 1,150 species, that includes some of the toughest creatures in the world. They can be found the world over; from the Himalayas 20,000 ft above sea level, to the deep sea 13,000 ft below sea level, even in the polar regions and on the equator, where the environment is hardly accommodating. Although I wouldn't hold out any hope of seeing one with the naked eye, as most individuals range from 0.3 to 0.5mm long. The Natural History Museum exhibit depicted the survival abilities of these organisms as a cycle, which I thought worked rater effectively. First, when their surroundings become intolerable, certain species of Tardigrade are able to deflate, draw in their legs and coat themselves in a waxy substance. The resulting structure is called a tun, and is barrel-like in shape with the creature's claws protruding from it. In this state tardigrades are capable of reversibly suspending their metabolism in cryptobiosis, and many members of the species can regularly survive in this state for up to 10 years. At extremely low temperatures, the Water Bear's body can go from 85% water to just 3%, ensuring they are not ripped apart by the water in their bodies expanding during freezing. When re-hydrated, it can take as little as 4 minutes for the animal to bounce back from its near-death state. Natural selection has seemingly thought of every extreme environmental condition on earth; the harshest pressure (they can survive in close to vacuums), temperature, radiation (5,000gy of gamma rays compared to the lethal dose of 5-10gy for humans), dehydration and environmental toxins. Certain species can even survive in outer space! (slight sensationalism), and in my view they truly earn their title of extremophiles. Science has so much to learn from such a tiny animal, particularly the proteins they produce to protect their cells from apoptosis during dehydration. (this seems to be a theme of my blog now), and even if humankind never make inter-planetary colonisation a reality, the Tardigrade is an excellent candidate to be our intergalactic envoy.