As the pool shrinks from evaporation, its salinity increases and the pH changes. Water temperatures can be very high, while oxygen levels can be very low. After a pothole fills with water, the small ecosystem experiences many other changes. The net result is that not all eggs hatch at once and the species has a better chance of survival. Some organisms produce different types of eggs that hatch on different cues others lay eggs in different areas so that they experience slightly different environmental conditions. Oxygen content, temperature, and other physical and chemical factors of the water may be evaluated. However, the presence of water may not be the only cue used by eggs and dormant life forms to activate. Even vertebrates such as toads, which are found in other environments, display shorter development times when found in potholes. Most organisms living in potholes have very short life cycles, as brief as ten days, reducing the time water is required and allowing them to live in the shallow pools. Desert precipitation falls at irregular intervals, and once water enters a pothole there is no guarantee that there is enough for an organism to complete its life cycle. Pothole organisms not only have to endure dry spells, but also must evaluate conditions and decide when to break dormancy. egg, larva) that can survive desiccation, and will die if a pool dries up during another phase. Many tolerators have only one stage in their life cycle (e.g. In fact, brine shrimp have been hatched from cryptobiotic cysts that endured a flight on the outside of a spacecraft. This transfer maintains the structure and elasticity of an organism's cells during long periods of drought, and enables the organism to withstand the climatic extremes of the desert. Cryptobiosis is accomplished by a command center that remains hydrated while substituting sugar molecules for water throughout the rest of the body. This remarkable process, known as "cryptobiosis," is made even more remarkable by the fact that many cryptobiotic species can be rehydrated and become fully functional in as little as half an hour. rotifers, tadpole and fairy shrimp eggs) are able to tolerate a loss of up to 92 percent of their total body water. By burrowing, these animals are able to seal themselves in the layers of fine mud that often coat the bottom of potholes and form an impermeable crust. These animals have a waterproof layer like a shell or exoskeleton that prevents body tissues from losing too much water while a pool is dry. snails, mites) have a dormant stage resistant to drying out. In the case of tadpole, fairy and clam shrimp, adults must lay their drought-tolerant eggs before the pool dries up. If the pool dries out before the young mature, they die. In some cases, adults live in permanent water sources or on land and travel to temporary pools to mate and lay eggs. mosquitoes, adult tadpole and fairy shrimp, spadefoot toads). “Drought escapers” are winged insects, amphibians and invertebrates that breed in potholes but cannot tolerate dehydration (e.g. Pothole organisms have three main ways of dealing with drought. Many aquatic organisms are adapted to acquiring oxygen through water and suffer when exposed to air. In addition to the wide temperature fluctuations, ultraviolet light from the sun can damage body tissues. The most extreme conditions exist when a pothole is dry. As water evaporates, organisms must disperse to larger pools or tolerate dehydration and the drastic physical and chemical changes that accompany it. Surface temperatures vary from 140 degrees Fahrenheit in summer to below freezing in winter. To survive in a pothole, organisms must endure extreme fluctuations in several environmental factors. Potholes range from a few millimeters to a few meters in depth, and even the smallest potholes may harbor microscopic invertebrates. Throughout Natural Bridges, naturally occurring sandstone basins called “potholes” collect rain water and wind-blown sediment, forming tiny ecosystems where a fascinating collection of plants and animals have adapted to life in the desert.
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