Life survives in caves by adapting to the unusual habitat. Because sunlight does not penetrate beyond the twilight zone of a cave, the area just inside the entrance, plants that must capture energy from sunlight cannot grow. Therefore, the cave ecosystem is based on nutrients entering the cave via water and outside organisms venturing into the cave and depositing guano, eggs, debris, or their carcasses. These nutrients are in turn used by the organisms that spend their entire life cycles in the cave environment.
Staff members at Great Basin National Park found a new amphipod, also called a freshwater shrimp, in Model Cave. Cave biologist Steve Taylor and amphipod specialist John Holsinger described it as a new species to science in the latest edition of Subterranean Biology (8:39-47). They named it Stygobromus albapinus, or the White Pine amphipod, since it was found in White Pine County, Nevada. The amphipod is tiny, less than the size of a dime. It does not have eyes and is entirely white. It is only known from Model Cave, and Dr. Taylor noted that it is most likely restricted to the Snake Range. Its closest relative is over 120 miles away at Ruby Marshes.
Bacteria lives in moist areas of caves, feeding on organic material that has seeped with the water through the "solid" rock. Some limestone caves have bacterial colonies that are chemoautotrophic, or "rock eating". These bacteria can derive all their necessary food and energy from rocks, minerals, or dissolved chemicals. They can form an ecosystem that is totally independent of the life-giving light from the sun. Research would be needed to determine if Lehman Caves is home to bacteria of this type.
Animals who use caves fall into several different categories. A trogloxene is a species who uses caves, but does not spend its entire life cycle within one. Examples are chipmunks, mice, and pack rats. These animals are dependent on vegetation for food and must leave regularly to forage. Bats feed on flying insects, such as mosquitos, and so must also must leave the cave to find adequate food.
The nesting material brought into the cave and droppings left behind by these temporary residents is a major source of nourishment for another type of animal known as a troglobite.
Troglobites are species that spend their entire life cycles in caves and include cave crickets, spiders, psuedoscorpions and the smaller mites and springtails. Often troglobites have adapted to the cave environment through morphological changes such as the loss of eyes and pigment and lengthening of appendages, as is seen in the cave dipluran. Though adapted to survive in the unique cave environment, they are dependent on organic material packed in by other animals or washed in from the surface. They often must optimize meals that are few and far between.
Animals in the cave use a variety of senses to find needed shelter and food. Bats navigate through the pitch dark using echolocation, emitting sound waves and listening to the echo in order to located objects. Pack rats follow the scent of their urine trail to their nests, called middens. They will fill these nests with pine cones, aluminum can tops, or anything else interesting, even though they cannot see decorations in the darkness. Touch is also very important. Pseudoscorpions use their enlongated pinchers to feel the route in front of them.
Cave life typically deals with very slow changing conditions (constant temperature and near constant humidity), constant darkness, and uncertain food supply. Humans have unintentionally changed the ecology of Lehman Caves, particularly, by introducing more food sources (wooden steps, lint, etc.), opening two new entrances, and installing electric lights. The lights, entrances, and tour groups slightly affect the temperature of the cave. Light in the previously dark cave allows plants to grow. These plants, mostly algae, are a source of food for animals. This can change what species live in the cave and how they interact.
Park rangers are trying to reduce these effects on the cave by turning out lights when tours are not in the cave and by not allowing visitors to bring food or beverages on tours.
Life in most caves has been poorly studied by scientists. At Great Basin National Park resource managers and scientists from around the country participate in ongoing surveys and studies of cave life. Several previously unknown species have been documented in the last decade alone. The resource links on this page provide information on recent studies in park caves.
Learning as much as we can about cave life has the potential to affect our own lives. Recently, scientists have found bacteria in caves that might have medical benefits. The first step, though, is to preserve these species by protecting the cave environments they live in.
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Cinnabar is the common ore of mercury. It is generally found in a massive, granular or earthy form and is bright scarlet to brick-red in color. It occasionally occurs in crystals with a non-metallic adamantine luster. Cinnabar resembles quartz in its symmetry and certain of its optical characteristics. It has the highest refractive power of any mineral. Because of its mercury content, cinnabar can be toxic to human beings.
Generally, cinnabar occurs as a vein-filling mineral associated with recent volcanic activity and alkaline hot springs. It's deposited by epithermal ascending aqueous solutions (those near the surface and not too hot) far removed from their igneous source. Cinnabar is found in all localities that yield mercury. This mineral is still being deposited in the present day from the hot waters of Sulphur Bank Mine in California and Steamboat Springs, Nevada.