In a recent article on our blog, we described what the planet Earth actually is. There we leaned into the question of the age of the Earth, its genesis, but also what the Earth is made of. In this short article, we would like to continue describing our Planet, but this time we will focus our attention on a slightly more specific area of interest, and more specifically, we will take a look at the most extreme environments on Earth. We will briefly describe the methods used to study such environments and tell ourselves about organisms that have been able to adapt to extremely inhospitable conditions.
The Earth is full of extremely harsh environments that present different species of organisms with outstandingly difficult conditions in which to live. This requires very difficult adaptive strategies, but this does not mean that life in such environments is impossible. On the contrary, some animals or plants are able to adapt to harsh living conditions in extremely sophisticated ways. For the purposes of this thesis, we will look at four selected environments: polar areas, deserts, mountains and the depths of the oceans.
Let us start with the polar regions. What makes it so difficult for any organisms to live there? First and foremost, temperature is key. In Arctic areas, such as the Antarctic or Antarctica, it is not uncommon for temperatures to drop below -50°C. What organisms can cope at such temperatures? These include both plants and animals. We can mention various types of mosses and lichens here, for example. How do they adapt to conditions where there is rarely solid ground and only ice and snow everywhere you look? Well, mosses and lichens can survive through their ability to reduce metabolic activity during the winter, but also by forming an insulating layer on the Earth's surface where they have chosen to “live”. This is a very practical mechanism to minimise energy losses, while maximising the organism's performance in such unfavourable conditions as much as possible. What about animals, then? Species such as penguins, seals or even polar bears have, in the course of evolution, developed very thick fur (in the case of bears), thick layers of fat (seals) or water- and wind-resistant plumage (penguins), which provide an excellent insulator against the cold. Humans, unfortunately, do not possess any of these traits, so we have to be assisted in the cold by thick, specially designed clothing that allows us to function in cold temperatures.
What does a study of cleared areas look like then? In fact, various research methods are used, which are then combined to provide a coherent and detailed picture of the issue of interest. Satellite imaging is used to collect data on glacier movements, climate change or vegetation development. Scientists are also carrying out surface studies, observing fauna, taking soil and rock samples for various analyses. Marine research, climatology and meteorology studies are also conducted, and glaciers and the ecosystems there are studied. Ice core research also plays an important role, allowing palaeoclimatic studies to be carried out.
Let us now look at desert areas. Deserts are just as extreme an environment as polar areas, although they are rather their opposite. To each of us, a desert is most likely to be associated with an endless ocean of sand, dunes and dwarf plants dried out to a crisp. Such an association is of course correct, but there are also ice deserts. For the purposes of this work, however, we will only be interested in sandy deserts. The key element that makes up the extremes of this environment is also the temperatures, sometimes exceeding 50°C, but also the extremely low and infrequent rainfall. It definitely does not help either that the occurrence of water in desert areas is, to say the least, unprecedented. Extremely dry air, no water, scorching sun, hot as fire sand and no rainfall. What organisms would be able to withstand such a thing? As with glaciated areas, deserts have both animals and plants. Plants we may encounter in deserts include, for example, cacti, agaves, aloe vera, annuals, grasses and grass-like plants (for example, so-called sand grass), acacias, junipers or epiphytic plants. Plants living in deserts have developed very extensive and intricate root systems, but also water storage mechanisms, which allow them to store water resources in their tissues for a very long time, which in turn allows them to function fairly normally under these harsh conditions. If we are talking about animals, species such as gerbils, snakes of various kinds, geckos, hawks, owls, foxes, camels, but also various insect species should be mentioned here. The organisms listed have adapted differently to the desert conditions. Some are able to store water and fat from their food, others have a nocturnal lifestyle to avoid the heat of the day, some birds are able to fly for a very long time in search of water, and still others are able to adapt their metabolism to the current requirements and conditions of the environment.
What does a study of desert areas look like? As in the case of the polar regions, various research techniques and methods are used. Among these are direct field observations, during which information is collected on the region's fauna and flora, rainfall or temperature. Satellite observations are used to study, for example, sand migration. Geophysical research are carried out to determine the geological structure and composition of the desert floor. In addition, palaeoclimatic, meteorological, hydrological, biological and hydrogeological analyses are carried out. All these studies are aimed at understanding climatic changes throughout history, but also current changes in temperature, humidity, wind speed, rainfall, etc. They help to model the substrate of deserts, determine groundwater resources and dynamics, their availability and quantity, but also allow to assess the impact of climatic and anthropogenic changes on desert ecosystems.
Let us now take a look at how the mountain environment presents itself. In the case of mountains, altitude plays an important role. Depending on the height of the mountains, for example, the temperature and the amount of oxygen in the air change. It is these relationships that determine and regulate life in the high parts of the mountains, which for many are impossible to live in. However, this does not mean that life does not occur there at all. As is the case in deserts and polar areas, there are organisms here that have developed special characteristics that allow them to exist on a daily basis in such extremely difficult conditions. Plants such as Edelweiss live in the highest parts of the mountains and on the highest peaks. At first glance, this flower somewhat resembles a daisy. Its adaptive strategy is to develop an extremely short growing season, i.e. the period during which it grows. This mechanism is to prevent the plant from being damaged by strong winds and very sharp temperature drops. In terms of animals, the best example would be the mountain chamois. How did this species manage to adapt? Well, for one thing, mountain chamois have specially adapted hooves that allow them to navigate extremely difficult terrain, so they can even move at a vertical angle of 60. In addition to this, they are able to manage very low oxygen supplies at high altitude, which allows them to function “normally”.
Let us now discuss the oceans. Why are the oceans such a difficult environment to inhabit? First of all, the key element here is pressure, which increases with depth. At the water's surface, the pressure is about 1013 hPa (hectopascals), which is similar to the pressure in which humans function on a daily basis. 1013 hPa = 1 atmosphere. And this is where the stairs begin, because in the oceans the pressure increases by about 1 atmosphere for every 10 metres down. In the deepest parts of the ocean, such as the Mariana Trench, the pressure is about 1,000 atmospheres, which is 1,000 times greater than atmospheric pressure. Let us now perform a simple calculation to give you an idea of the scale of this phenomenon: on average, the air pressure in a car tyre is 2 - 2,5 atmospheres. At the bottom of the Mariana Trench, the pressure is, as we mentioned, 1,000 atmospheres, which is about 400 times greater than in a standard car tyre. In terms of kilograms per square metre, a pressure of 1,000 atmospheres is equal to the pressure of 10332300 kg/m2. This is very, very high. This is why it is so difficult for us to study deep-sea environments, because testing using machines capable of withstanding such pressures is extremely expensive. This is why we know so little about what happens in the ocean depths. Another important element is the lack of light, which for many organisms is essential for life. The limit below which light does not reach is (under exceptionally good conditions) around 300 m. Below this depth, we are dealing with the so-called aphotic zone, i.e. absolute darkness. So how do organisms cope in such conditions? There are many fish, molluscs or crustaceans that have been able to develop certain characteristics that allow them to survive. For example, deep-sea fish have developed luminescent organs with which they illuminate the depths in order to search for food or to attract food to themselves. They also have specially developed sense organs that help them with spatial orientation. Some species of crayfish, on the other hand, have learnt to use senses other than sight in such a way as to locate food or to take refuge from a predator (for example, the shark crayfish). Some crabs have developed extremely strong carapaces that can withstand high pressure. At the same time, they have extremely flexible body structures that allow them to move without much difficulty. There are also organisms that have an extremely slow metabolism and their adaptive strategy is to consume very little energy and be able to obtain food periodically.
To explore the ocean depths, scientists use different strategies and methods. Of course, the use of submarines or bathyscaphes is the order of the day. Underwater robots are also used, for example to collect samples of material that are then analysed. Underwater robots are most commonly used where manned vessels cannot operate due to the potential risk to personnel. The use of ocean probes and so-called hydrophones is also quite common. Ocean sounders are used to analyse data such as salinity, migration of water masses, electrical conductivity and physical properties of water. Hydrophones, on the other hand, are used to record the various frequencies and sounds that certain aquatic animals may make.
Summarising the above, it is safe to say that there is really no environment in the world to which life could not adapt in some way. Of course, the human species, by virtue of its physiognomy and physiology, cannot withstand certain conditions, so we have to live in habitats with strictly defined norms. Fortunately, animals, plants or non-human organisms in general develop very different adaptive strategies that allow them to inhabit outstandingly extreme conditions. This in turn leads to our planet having an outstanding biodiversity, which also makes our lives better.
Author: Kuba Żurawski
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