The Wonders of Water...and Water Bears!
couple of thangs I threw together this morning that some might find interesting...
Water (H2O) is often perceived to be ordinary as it is transparent, odorless, tasteless and ubiquitous. It is the simplest compound of the two most common reactive elements, consisting of just two hydrogen atoms attached to a single oxygen atom. Indeed, very few molecules are smaller or lighter. Liquid water, however, is the most extraordinary substance.
Although we drink it, wash, fish and swim in it, and cook with it (although probably not all at the same time), we nearly always overlook the special relationship it has with our lives. Droughts cause famines and floods cause death and disease. It makes up over about half of us and, without it, we die within a few days. Liquid water has importance as a solvent, a solute, a reactant and a biomolecule, structuring proteins, nucleic acids and cells and controlling our consciousness. H2O is the second most common molecule in the Universe (behind hydrogen, H2), the most abundant solid material and fundamental to star formation. Life cannot evolve or continue without liquid water. Within this fluid occurs the universal exchange of qualities. Its duplicitous nature gives water an aptitude for submitting to as well as animating the qualities it bears. It is a substance that continually 'struggles against its own creation' as if constantly slipping from the grasp of man's rational control and organisation. Liquid water's unique properties and chameleonic nature seem to fit ideally into the requirements for life as can no other molecule.
But the molecular structure of water has remained a mystery, with the substance exhibiting many strange properties that are still poorly understood. There is a very long list of the properties of water that mark the liquid out as being far from normal, not to say weird. But if it wasn't for water's profound peculiarities, life would be impossible here on Earth and most likely elsewhere too.
For instance, being made of hydrogen and oxygen - two very light elements - water should not really exist as a liquid under the conditions here on Earth. If water behaved normally, it would be a gas, which is no use as a medium for bringing together the chemical ingredients of life and hosting the biochemistry of living things.
Thus far, no single computer water model accounts for and explains the many anomalous properties of water. But in the words of one research scientist. "If we don't understand this basic life material, how can we study the more complex life materials - like proteins - that are immersed in water? We must understand the simple before we can understand the complex."
Revealing the Mysteries of Water
Researchers reveal the internal dance of water
67 Anomalous properties of Water (this list keeps growing...was 41 of them about 10 years ago IIRC)
The List of Water Anomalies Expands Even More
The New Mystery of Water
Water - The Marvelous Molecule on BBC radio
The Waters of Life
The Mystery, Art, and Science of Water - a multi-disciplinary examination
The Floating Water Bridge - Video
Water Bridge explanations:
Water Bears (Tardigrades)
Water Bears are fascinating microscopic animals. Biologists struggled for years to classify them before finally placing them in their own phylum - Tardigrade (i.e. slow moving animal). With a length of only 0.05 to 1.25 mm they among the smallest of multicellular animals. There are about 1000 species and most of them move in a sluggish, bear-like manner...hence the name.
Water Bears are polyextremophiles; scientists have reported their existence in hot springs, on top of the Himalayas, under layers of solid ice and in ocean sediments. Many species can be found in a milder environment like lakes, ponds and meadows, while others can be found in stone walls and roofs. Tardigrades are most common in moist environments, but can stay active wherever they can retain at least some moisture. They are abundant in moss and lichen.
Although they lack a circulatory system and respiratory organs, the anatomy of a water bear is extremely complex. Tardigrades have a body with four segments (not counting the head), four pairs of legs without joints, and feet with claws or toes. The cuticle contains chitin and is regularly moulted. They have a ventral nervous system with one ganglion per segment, and a multilobed brain, two pigment-cup eyes and a mouth. They show signs of youth and old age. Females and males occur in most species of water bears. The males actively seek out the females, many species have complicated courtship behaviour and mating rituals.
You can see a variety of images here:
Because they have chubby bodies and walk upright on legs they are difficult to view with light microscopy...the electron microscope reveals the best detail but a good motion video can be found here:
OK, so it's a little tiny kinda cute critter...what's so wonderful about that you ask? Well, it may be that these little critters are the hardiest and toughest animal on earth! Tardigrades are one of the few groups of species that are capable of reversibly suspending their metabolism and going into a state of cryptobiosis. Several species regularly survive in a dehydrated state for nearly ten years. Depending on the environment they may enter this state via anhydrobiosis, cryobiosis, osmobiosis or anoxybiosis. While in this state their metabolism lowers to less than 0.01% of normal and their water content can drop to 1% of normal. Their ability to remain desiccated for such a long period is largely dependent on the high levels of the non-reducing sugar trehalose, which protects their membranes. In this cryptobiotic state the tardigrade is known as a tun and can withstand extreme environments that should kill it or any other multicellular animal.
Tardigrades have been known to withstand the following extremes while in this state:
* Temperature — tardigrades can survive being heated for a few minutes to 151 °C (424 K), or being chilled for days at –200 °C (70 K), or for a few minutes at –272 °C. (~1 degree above absolute zero).
* Pressure — they can withstand the extremely low pressure of a vacuum and also very high pressures, more than 1200 times atmospheric pressure. It has recently been demonstrated that tardigrades can survive the vacuum of open space and solar radiation combined for at least 10 days. Recent research has revealed that they can also withstand pressure of 6,000 atmospheres, which is nearly six times the pressure of water in the deepest ocean trench.
* Dehydration — tardigrades have been shown to survive nearly one decade in a dry state.
* Radiation — tardigrades can withstand median lethal doses of 5000 Gy (gamma-rays) and 6200 Gy (heavy ions) in hydrated animals (5 to 10 Gy could be fatal to a human). In September 2008, a space launch (Foton-M3) showed that tardigrades can survive the extreme environment of outer space for 10 days. After being rehydrated back on Earth, over 68% of the subjects protected from high-energy UV radiation survived and many of these produced viable embryos, and a handful survived full exposure to solar radiation, making these the only animals shown to be able to survive the vacuum of space.
This amazing ability are not understood.
more tardigrade links:
Only thing this seems to prove is that computer models aren't always accurate.
uhm well the water models...computer and otherwise...are accurate but incomplete.
I remember reading a little about this on PopSci.com a couple months back.
Great post, I learned quite a bit.
Thanks for sharing im gonna have a good read tonight.
Thanks for that information Makalu, I never knew about a Water Bear before. It was a good read.
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