The main feature of the aquatic habitat is ... The properties of the aquatic habitat

Water has long been not only a necessary condition of life, but also the habitat of many organisms. It has a number of unique properties, which we will discuss in our article.

Water habitat: characteristic

In each habitat there is an effect of a number of environmental factors - those conditions in which populations of different species live. In comparison with ground-air, the water habitat (grade 5 studies this topic in the course of geography) is characterized by high density and perceptible pressure drops. Its distinctive feature is a small amount of oxygen. Aquatic animals, called hydrobionts, have adapted differently to life under such conditions.

Ecological groups of hydrobionts

Most of the living organisms are concentrated in the water column of the World Ocean. They are grouped into two groups: planktonic and nektonic. The first include bacteria, blue-green algae, jellyfish, small crustaceans, etc. Despite the fact that many of them can swim on their own, they are not able to withstand strong currents. Therefore, plankton organisms move with a current of water. Adaptability to the aquatic habitat is manifested in them in small sizes, a small specific weight and the presence of characteristic outgrowths.

Non-nutrient organisms include fish, cephalopod mollusks, aquatic mammals. They do not depend on the strength and direction of the current and move in the water on their own. This is facilitated by the streamlined shape of their body and well-developed fins.

Another group of hydrobionts is the periphery. It includes aquatic inhabitants that attach to the substrate. These are sponges, some algae, coral polyps. On the border of the water and land-air environment, the neuston lives. Basically, these are insects that are associated with an aqueous film.

Properties of aquatic habitat

Among environmental factors of the aquatic environment, the leading role belongs to the temperature regime and illumination. They can be considered limiting. Thus, the maximum depth at which plants occur is about 270 m. It is there that red algae absorb scattered light. There are simply no deeper conditions for photosynthesis.

The water habitat, whose characteristic is very extensive, differs also by such an indicator as pressure. Due to its influence, animals can live only at certain depths.

Temperature conditions

The main feature of the aquatic habitat is that, in comparison with air, temperature differences are less noticeable here. For example, in the surface oceanic layers, this figure does not exceed 10-15 degrees above zero. And at a depth the water temperature is constant. Its lower limit reaches -2 degrees Celsius. Such a temperature regime is provided by a high specific heat of water.

Illumination of water bodies

Another major feature of the aquatic habitat is that with depth the amount of solar energy decreases. Therefore, organisms whose lives depend on this indicator can not live at significant depths. First of all it concerns algae. Deeper than 1500 m, light does not penetrate at all. Some crustaceans, coelenterates, fish and mollusks possess the property of bioluminescence. These deep-water animals themselves produce light by oxidizing lipids. With the help of such signals they communicate with each other.

Water pressure

Especially strongly with immersion, there is an increase in water pressure. At 10 m this indicator increases on the atmosphere. Therefore, most animals are adapted only to a certain depth and pressure. For example, ringworms live only in the tidal zone, and the coelacanth is lowered to 1000 m.

The displacement of water masses

The movement of water can have a different nature and causes. Thus, the change in the position of our planet in relation to the Sun and the Moon determines the presence of tides in the seas and oceans. The force of gravity and the influence of wind causes flow in rivers. The constant movement of water plays an important role in nature. It causes migratory movements of various groups of hydrobionts, food sources and oxygen, which is especially important. The fact is that the content of this life-giving gas in water is 20 times lower than in the terrestrial-air environment.

Where does oxygen appear in the water? This is due to the diffusion and activity of algae that carry out photosynthesis. Since their number decreases with depth, the oxygen concentration also decreases. In the bottom layers this indicator is minimal and creates almost anaerobic conditions. The main feature of the aquatic habitat is that the concentration of oxygen decreases with increasing salinity and temperature.

Salinity index of water

Everyone knows that the water bodies are fresh and salty. The last group includes seas and oceans. The salinity index is measured in ppm. This is the amount of solids that are in 1 g of water. The average salinity of the World Ocean is 35 ppm. The lowest indicator is the sea located at the poles of our planet. This is due to the periodic melting of icebergs - huge frozen blocks of fresh water. The most salty on the planet is the Dead Sea. There is not a single species of living organisms in it. Its salinity is approaching 350 ppm. Of the chemical elements in water, chlorine, sodium and magnesium predominate.

So, the main feature of the aquatic habitat is its high density, viscosity, low temperature difference. The life of organisms with increasing depth is limited by the amount of solar energy and oxygen. Aquatic inhabitants, called hydrobionts, can move by water or move independently. For life in this environment, they have a number of adaptations: the presence of gill respiration, fins, streamlined body shape, a small relative mass of the body, the presence of characteristic outgrowths.