- from Water
All life on Earth depends on water. But what if there’s not enough water in a place, such as in a desert? Or what if the water is supersalty, superhot, or superoily?
Extreme water conditions call for extreme methods of survival. Some animals have tricks or traits to cope with extreme water conditions. If a water hole dries up, a lungfish can survive because it has lungs (organs for breathing oxygen in air) in addition to gills (organs for breathing oxygen in water).
Anywhere that water extremes exist, so do some of the toughest life-forms on Earth!
▲ Superdry and Freezing
One of Earth’s driest places is the Dry Valleys, a frozen desert in Antarctica. There’s no rain and very little snowfall. Yet many organisms, including brown clumps of bacteria, live in spaces between rocks, where a tiny amount of water remains trapped. The water is frozen all winter, along with the bacteria, but summer heat provides a brief thaw.
▲ Superdry and Scorching
The moloch lizard, also called the thorny devil, lives in the Australian desert. Not enough rain falls to quench its thirst, so it must get its liquid elsewhere. Molochs have spines slanted toward the corners of their mouths, which catch morning dew and “feed” it to them. Molochs also eat ants—about a thousand in one sitting.
Check It Out!
Why would an animal live in an extreme water environment instead of moving where the water’s just right?
One reason is that there’s no competition from other animals. As long as an animal can survive the tough conditions, it has food, water, and shelter to itself. Another reason is that one animal’s hell is another animal’s heaven. The scalding temperature and chemical soup at a hot-water vent deep in the ocean kill many life-forms, but some bacteria eat these chemicals and thrive.
Minerals are materials that can be dissolved in water. Hard water is water containing minerals (which themselves contain elements such as iron, copper, cadmium, arsenic, and nickel). It is not the hardness of the materials that determines the hardness of the water but the amount of dissolved materials in the water. (Oxygen and hydrogen do not possess the quality of hardness in the liquid state.) Hard water is a problem because it can clog water pipes. It also requires more soap to get skin or clothes clean. Some of the dissolved minerals may coat your skin and cause itchiness. Iron and other minerals are dissolved in the Rio Tinto, a river in Spain. Oxygen from bacteria in the water causes the iron to rust, tinting the water red (above).
Peat bogs are wetlands that are almost as acidic (sour) as vinegar. The acidity is caused by a moss called sphagnum, a spongy plant that absorbs water and minerals and releases hydrogen gas. The hydrogen makes the water acidic. Few animals can survive there. Sundew plants have evolved a unique way of getting nutrients in a nutrient-poor bog. Their sticky surfaces trap and digest passing flies.
The shallow Great Salt Lake in Utah is almost eight times saltier than the oceans. Salt attracts the less-salty liquid inside organisms, causing them to dehydrate. Not many animals can withstand briny (salty) waters. Brine shrimp (above) are an exception. To avoid drying out, they keep their insides as salty as the water (creating a stabilized balance).
Life in Boiling Water!
Deep-sea water is normally around the freezing point. Yet a crack in the ocean floor can produce “smokers,” or hot-water vents. Superhot, mineral-rich fluid from below the Earth’s crust flows up through the crack. An organism called Pyrolubus fumarii thrives in vents just above the boiling point. It stops growing when the temperature gets too “cold”—about 194°F!