You surely don’t know this one but you can still give it a try… Which animal can withstand environments as cold as minus 328 degrees Fahrenheit (minus 200 Celsius) or highs of more than 300 degrees F (148.9 C)*? And they can still be around after humanity is long gone. Not this alone, they can survive radiation, boiling liquids, massive amounts of pressure (up to six times the pressure of the deepest part of the ocean and even the vacuum of space without any protection). In fact, a study published in Current Biology in 2008 found some of their species surviving 10 days at low earth orbit while being exposed to a space vacuum and radiation.
We are talking about tardigrades: near-microscopic animals with long, plump bodies and scrunched-up heads. Often called water bears or moss piglets, tardigrades have eight legs and hands with four to eight claws on each. These tiny animals, strangely cute, are almost indestructible and can even survive in outer space.
Tardigrade is a phylum, a high-level scientific category of animal and there are 1,000-plus known species within tardigrades. Ranging between 0.05 mm to 1.2 mm (0.002 to 0.05 inches) long, they usually don’t get any bigger than 1 mm (0.04 inches) long. The tardigrades prefer living in sediment at the bottom of a lake, wet environments and moist pieces of moss.
Discovered by German pastor Johann August Ephraim Goeze back in 1773, tardigrades were named tardigrade meaning slow stepper. Three years later, Italian biologist Lazzaro Spallanzani found that they could survive extreme conditions by making a transformation. It was discovered that they would curl into a dehydrated ball called tun and reach an almost death-like state called cryptobiosis. And once they were reintroduced to water, the tardigrades would come back to life in a few hours. In cold temperatures, they form into a special tun that prevents the growth of ice crystals.
Another strange fact about tardigrades is their ability to a defense mechanism in water. When the oxygen level is low, they stretch out and allow their metabolic rate to reduce thereby enabling the muscles to absorb enough oxygen and water for them to survive.
A BBC report on tardigrades has shown them surviving on fluids. Then they also suck juices from algae and lichens. In fact, some of their species are carnivores and cannibals. They reproduce through sexual and asexual reproduction, depending on the species; laying one to 30 eggs at a time. During sexual reproduction, the female lays the eggs and the males fertilise them. In asexual reproduction, the female lays the eggs and they develop without fertilisation.
* Smithsonian magazine