Adaptations to Temperature, Moisture, and Aquatic Environments
Adaptations to Temperature
Annual plants die in the unfavorable season, and many trees reduce their activity. Homeothermic animals (birds and mammals) maintain a constant temperature; some hibernate, entering a state in which they slow down their activity. Poikilothermic animals have a temperature similar to the environment and migrate under unfavorable seasons.
Adaptations to Moisture
Water-loving plants live in very wet and dark environments. Drought-tolerant plants live in dry areas; their leaves are needle-shaped to avoid evaporation. Animals have special structures that prevent water loss by transpiration (e.g., mammalian hair).
The Aquatic Environment
This includes saltwater (seas and oceans) and freshwater (rivers and lakes). Each of these biotopes and environments has a biocenosis with specific characteristics.
Determinants of the Aquatic Environment
- Light: The presence or absence of light determines the existence of photosynthetic organisms. The amount of light depends mainly on transparency and depth. Water clarity is less than that of air; the intensity of light diminishes with depth. The zone to which light reaches is the photic zone, and that where no light reaches is the aphotic zone.
- Temperature: It depends on the amount of oxygen dissolved in water and currents.
- Salinity: This is one of the factors that most influences the distribution of aquatic species and expresses the concentration of dissolved mineral salts.
- Amount of oxygen: The greater the contact area between the atmosphere and water, the greater the oxygen exchange.
- Hydrostatic pressure: Increases every ten meters of depth.
- Viscosity: In an aquatic environment, it is very high, which allows organisms to be suspended in water but hampers their movement.
- Density: Accounts for the buoyancy of living beings, which just need hard or rigid parts in their body.
- Water movements: Have a fundamental influence on the coast and in the upper reaches of rivers.
Adaptations to the Aquatic Environment
- Adjustments to light: Cause photosynthetic organisms to be distributed based on the ability of their pigments to capture light energy. Many animals have evolved to produce light organs.
- Adaptations to hydrostatic pressure: Many animals can adapt to different pressures.
- Adaptations to salinity: Many animals can regulate their internal salt concentration.
- Adaptations to high density and viscosity of water: Some use propulsion mechanisms to move. Certain plants and algae have small air-filled bladders that allow them to float.
- Adjustments to the flow of water: Aquatic plants have flexible stems that do not break; some are secured to the bottom.
The Biosphere, Ecosystems, and Biomes
The set of all living things that inhabit the Earth is the biosphere. No organism lives in isolation. The distribution of living beings on the planet is not uniform but depends on environmental conditions.
An ecosystem is the set of living beings that inhabit a particular place, the characteristics that define their environment, and the relationships established between them and with the environment.