Adaptation of Organisms to Extreme Environment
In order to cope with extreme environmental conditions microbes, plants as well as animals have developed the ability to adapt and metabolize under harsh environmental conditions. The process by which plant and animal changes in order to fit in to its environment are called adaptation. It may occur in any area, from internal structure to locomotion (“Science & Nature: Animals,” 2007).
Every organism, such as plants and animals adapt themselves to the environment in which they live in order to survive. Sharks for instance have fins, streamlined bodies, sharp teeth which enable them to swim quickly and catch food in the ocean. Leaves are present on trees to catch sunlight as well as roots for the purpose of collecting water and nutrients which are present from the soil. When an organism are not adapted to the environment they will not survive, for instance sharks cannot live on land and trees cannot live in the ocean because they were not adapted to that particular environment (“Adaptation,” 2004).
Our environment changes over time and as it change both plants and animals living in that environment must change and adapt to it. In order to adapt to changing environment the organisms must: 1) change the shape and function of their bodies which is called physical adaptation; 2) change their behavior often called as behavioral adaptation; or 3) organism must move to a different environment that they need, thus, preventing possible extinction of the organism (“Adaptation,” 2004).
In deserts, wherein there are extreme temperature fluctuation as well as water shortages, animals have the ability to alter their internal environment and develop behavioral or physiological adaptive strategies as well as morphological adaptation (“Plant and Animal Adaptation, 2007).
The entire paper aims to answer how organisms survive on extreme environments. This paper discusses the mechanisms by which the species are adapted to survive under physical conditions of extreme environment.
Mostly common to many mammals, insects as well as birds in the desert is the use of burrows. Many organisms utilized a burrow for them to have little or no exposure to sunlight. In order to make the water available for a second round consumption, according to Rundel and Gibson, (1996) some species of rodents purposely pant inside burrows.
Another adaptation to reduce overall exposure of an organism to high light and temperature levels is the use of shady micro-habitats. One common adaptation in birds such as turkey and vultures is the presence of excretion on the feet or legs which evaporate and cools the organism as the excretion evaporates which is known as Urohydrolysis. Nocturnal activity, wherein activity of an organism occurs at night, reduces the amount of exposure to light and heat extremes. Another adaptation of organism is migration to other areas wherein they move or transfer to a place where there are more abundant water or to a place where the temperature are cooler. In addition to that, hibernation or estivation during the hotter or cooler times of the season is another physiological adaptation of the organism (“Plant and Animal Adaptations,” 2007).
Depending on the seasons of greatest moisture or coolest temperatures desert plants have developed a lifestyle using behavioral adaptations. These types of plants are usually referred to as perennials and annuals. Perennials are plants that live for several years and which often survive by remaining dormant during dry periods of the year then when water becomes available they spring to life. On the other hand annuals are plants that live for only a season wherein most of them germinate only after heavy seasonal rain, and then complete their reproductive cycle quickly. In the spring, they bloom extraordinarily for a few weeks. This accounts for most of the wildflower explosions of the desserts. Until the next year’s annual rains, the seeds which are heat and drought resistant remain dormant in the soil (“Desert Plant Adaptations, 2007).”
For some animals gular or tongue fluttering serves as a cooling method. To reduce surface contacting the hot surface or to increase surface area where moisture may be collected from morning fogs which are commonly observed to many desert mornings, body “acrobatics” wherein body positions are altered is one of the adaptations of organism (“Plant and Animal Adaptations,” 2007).
In order for an organism to survive in desert ecosystems wherein there are high and fluctuating temperatures and extremely low water availability they develop an adaptation. As a response to this extreme environmental condition, dessert plants were observed to have enhanced cuticle, and a waxy covering which prevents water loss. To enable the plants, to reach water sources beneath the soil they developed long vertical roots. They have shallow, radical roots which extend horizontally to maximize water absorption at the surface. Tricombs, hair-like projections are present thereby creating a thick boundary layer that function to deflect heat as well as IR wavelengths. In order to discourage herbivores and increase boundary layer effects they developed spines and hairs.
To allow accumulation of C4 acids desert plants have increased size and number of vacuoles. They were observed to have small and narrow leaves to decrease absorption of heat from the sun and they have rotating leaves which enable the plant to orient it leaves away from maximize exposure to the sun. They also have recessed as well as reduced stomata which decreases water loss. To reduce surface-to-volume ratio and favor water conservation they developed succulent leaves. Leaf polymorphism were observed in which they form broad leaves when soil moisture is high and narrow leaves follow as the water is used up (“Plant and Animal Adaptation,” 2007).
According to an article entitled, ‘Desert Plant Adaptations,’ (2007), “plants that have adapted by altering their physical structure are called xerophytes.” An example of which is Cacti, which usually have special means of storing and conserving water and often have few or no leaves, which reduces transpiration. Cactus is considered the most drought-resistant plants on the planet. Their leaves are absent, they have shallow root systems. They were able to store water in their stems, wherein spines are present for shade and waxy skin to seal the moisture “Phreatophytes on the other hand, are plants that have adapted to arid environments by growing extremely long roots, thereby allowing them to acquire moisture at or near the water table”
Animals on the other hand have different adaptations. An important Factor to reduce heat absorption is coloration. More light are reflected with lighter colored coat as compared to darker colored coat wherein it can absorb more light. As a result, the body temperature of an organism is reduced and more water is conserved. In order to increase surface area and promote heat loss some organism have enlarged appendage. Presence of feathers, and hair as well as body fats which protects the tissues serves as insulators to the organism (“Plant and Animal Adaptation,” 2007).
Interactions of Organism at Extreme Environment
Extremophiles Present in Extreme Environments
Studies shows, that NASA Scientist discovered new species of organism in Mars-like environment, thriving without oxygen, and growing in salty alkaline condition. As published in May 2003 issue of the International Journal Systematic and Evolutionary Microbiology, the two NSSTC scientists, Richard Hoover and Dr. Elena Pikuta, have identified a species of Spirochaeta Americana which was isolated from an oxygen-deprived mud sediments from Northern Carolina’s Mono Lake- a salty, alkaline lake in an enclosed volcanic basin. Spirocheata is a long, thin bacteria and an extremophile which means it is an organism that are able to survive, and adapt to an extreme environment.
Although there are a lot of bacteria and archaea, there are only about 6000 species which have been described and validly named. Only a small fraction of them were proven to be extremophiles. As stated by Pikuta, “The environment that these bacteria inhabit would be distinctly inhospitable to many other life forms, including Humans.” Unlike Spirochaeta americana that can grow without oxygen, humans as well as other multi-cellular organisms need oxygen in order to survive. In order to live humans need to drink fresh water, while this organism on the other hand can thrive in an environment with high-mineral at salty. In terms of pH scale of 0-14, humans prefer a mid- range between 6.5 and 7.5, while Spirochaeta prefers 8.0 to 10.5 (“NASA Scientist Discovers New Species of Organism in Mars-like Environment,” 2007).
Acidophiles present in Acidic Environments
These are organisms that can withstand and even thrive in acidic environments wherein the value of pH ranges from 1-5. These include organism such as eukaryotes, bacteria as well as archaea which can be found in a variety of acidic environments, including sulfuric pools and geysers, areas polluted by acid mine drainage, or even our own stomach. High Acid levels normally, destroy cells, however, acidophiles have specialized mechanisms to maintain pH of their internal cellular at constant level of usually 7.2.
This mechanisms include 1) passive pH regulation wherein defenses rely on enforcing the cell membrane against an unfavorable environment. In order to slow down diffusion of molecules into the cell, as a response, some microorganisms secrete a biofilm, while others are able to change their cell membrane to incorporate substances such as fatty acids which can protect the cell. In addition to that some microbes regulate their pH by secreting buffer molecules that help to raise pH; and 2) active pH regulation which gives the organism the ability to pump hydrogen ions, at a constant rate, out of their cells. With these mechanisms the organism are able to keep their internal ph at around 6.5 to 7.0 (RichLein M., 2006)
Alkaliphiles present in Alkaline Environments
The term alkaliphiles are used for microorganisms that can be able to grow well at ph values above 9. Most often they can grow between 10 and 12, however, they cannot grow or in some cases growth is slow at near neutral pH value of 6.5 (Horokoshi, K. 1999). In alkaliphilic bacteria, internal pH can be maintained by both active and passive regulation mechanism. The two modes of passive regulation are cytoplasmic pools of polyamines and low membrane permeability (Bordenstein, S., 2007).
Psychrophiles Present in Very Cold Environments
According to Morita (1975), an organism which can exhibit growth under 15 0C or lower, were called Psychrophiles. Psychrophilic bacteria, compared to other prokaryotes have many unique qualities. By having largely saturated fatty acids in their plasma membranes, they were able to adapt themselves to thrive in cool environments. Research shows that these psychrophiles contain polyunsaturated fatty acids which were proven to be absent in prokaryotes. They contain enzymes that continue to function although at reduced rate, at near freezing ambient temperatures and also they have the ability to produce proteins that are stable at even at cold temperatures (Montross, S.N., 2006).
Thermophiles Present in Extremely Hot Environment
Microorganisms that can survive and grow in temperature between 60 to 108 degrees Celsius are called thermophiles. These organisms can be isolated from marine and terrestrial geothermally-heated habitats which includes shallow terrestrial hot springs, hydrothermal vents, sediments from volcanic islands as well as deep sea hydrothermal vents (Encyclopedia of Environmental Microbiology,” 2002).
Microorganisms were found growing in boiling hot springs of Yellowstone National Park. This was discovered by Thomas Brock, in 1966. Although humans and other animals cannot tolerate this kind of environment it was found out that life especially prokaryotic life can withstand and able to adapt to boiling hot springs which could be fatal to other life forms. All thermophiles require hot water environment in order to survive, some of them thrive in an environment where there is high level of sulfur or calcium carbonate, acidic water, or alkaline springs. These organisms can thrive in extremely hot environment (sometimes as high as 140 degrees Celsius), because of their extremozymes, an enzymes geared to work under high temperatures. It has amino acids which can be able to retain their twisted and folded 3d structures even when exposed in high heat (Beal, H., 2007).