The habitat of organisms is constantly exposedeffects of various variable factors. Organisms are capable of reflecting the parameters of the environment. In the course of historical development, living organisms have mastered three habitats. Water is the first of them. In her life was born and millions of years developed. Ground-air - the second environment in which animals and plants emerged and adapted. Gradually transforming the lithosphere, which is the upper layer of the land, they created the soil, which became the third habitat.
Each species of individuals living in a particularenvironment, characterizes its own type of energy and metabolism, the preservation of which is important for its normal development. In the condition of the environment, which threatens the body with a violation of the balance of energy and substance exchange, the organism either changes its position in space, or transfers itself to more favorable conditions, or changes the activity of metabolism.
Not all factors play an equivalent role in lifeaquatic organisms. By this principle, they can be divided into primary and secondary. The most important of these are the mechanical and dynamic characteristics of bottom soil and water, temperature, light, suspended and dissolved in water, and some others.
Factors of aquatic environment
The water habitat, the so-called hydrosphere,occupies up to 71% of the total area of the planet. The water volume is almost 1.46 billion cubic meters. km. Of these, 95% is the World Ocean. Fresh water consists of glacial (85%) and underground (14%). Lakes, ponds, reservoirs, bogs, streams and streams occupy slightly more than 0.6% of the total fresh water, 0.35% is enclosed in soil moisture and atmospheric vapor.
The aquatic habitat is inhabited by 150 thousand species of animals (7% of all living creatures of the Earth) and 10 thousand plant species (8%).
In the equator and tropical zones, the animal worldand plants is most diverse. With the removal of these belts in the northern and southern directions, the qualitative composition of aquatic organisms becomes poorer. The organisms of the World Ocean are concentrated mainly off the coast. Life is practically absent in open waters located far from the coast.
Properties of water
The physical properties of water determinethe vital activity in it of living organisms. Among them, first of all, thermal properties are important. These include large heat capacity, low thermal conductivity, high latent heat of evaporation and melting, expansion property before freezing.
Water is an excellent solvent.In the dissolved state, all consumers absorb inorganic and organic substances. The aquatic habitat facilitates the transport of substances within organisms, the decay products also stand out with water.
High surface tension of water keeps alive and inanimate objects on the surface and fills capillaries, due to which terrestrial plants feed.
Transparency of water promotes photosynthesis at great depths.
Ecological groups of aquatic organisms
- Benthos are such organisms that are attached to the ground, lie on it or live in the thickness of precipitation (phytobenthos, bacteriobenthos and zoobenthos).
- Periphyton - animals and plants that are attached or held by the stems and leaves of plants or for any surface that rises above the bottom and floats down the water.
- Plankton - free floating plant or animal organisms.
- Necton - actively floating organisms with streamlined forms of the body, not related to the bottom (squid, fish, whales, pinnipeds, etc.).
- Neuston - microorganisms, plants and animals that live near the water surface between water and air. These are bacteria, protozoa, algae, and larvae.
- Pleiston - hydrobionts, partially located in water, and partly above its surface. These are sailfishes, siphonophores, duckweed and arthropods.
The inhabitants of rivers are called potobemontami.
The aquatic habitat is characterized bypeculiar conditions of life. The distribution of organisms is strongly influenced by temperature, light, water currents, pressure, dissolved gases and salts. The living conditions in marine and continental waters are very different. Sea water is a more favorable environment, close to a physiological solution. Continental waters for their inhabitants are less favorable.