Saltwater and freshwater fish have evolved different osmoregulatory strategies due to their distinct environments. Saltwater fish live in a hypertonic environment, where the water has a higher solute concentration than their internal fluids. To prevent dehydration, these fish actively drink seawater and excrete the excess salts through specialized cells in their gills and concentrated urine. In contrast, freshwater fish reside in a hypotonic environment where the surrounding water has a lower solute concentration than their body fluids. They face the challenge of water constantly entering their bodies. To counteract this, freshwater fish do not drink water actively; instead, they absorb salts through their gills and produce large quantities of dilute urine. This helps them to expel the excess water while retaining the necessary solutes. These adaptations are crucial for maintaining their internal ionic and osmotic balance in their respective environments.

Desert plants face extreme environmental conditions, including high temperatures and limited water availability, making osmoregulation a key survival strategy. These plants have adapted to conserve water while managing their internal solute concentrations. One common adaptation is the development of a thick cuticle and reduced leaf surface area to minimize water loss. Additionally, desert plants often accumulate solutes in their cells to lower their water potential, which helps retain water and prevent excessive loss through transpiration. Some desert plants have specialized structures like succulent leaves or stems that store water. The roots of these plants can also extend deep into the soil to access water sources. By controlling their water and solute balance, desert plants can survive and thrive in harsh arid environments, illustrating the importance of osmoregulation in plant adaptation and survival.

Turgor movement in plants is a direct result of osmoregulatory mechanisms that alter the water content in certain plant cells, causing movement. This phenomenon is observed in plants like Mimosa pudica (the sensitive plant), where a stimulus like touch leads to rapid changes in cell turgor pressure. When stimulated, cells at the base of the leaves lose water rapidly, mainly due to the efflux of ions which decreases the water potential inside these cells. As a result, water moves out of the cells, reducing turgor pressure and causing the leaves to fold or droop. This mechanism is an adaptation to environmental stimuli and is driven by the plant's ability to regulate the water and solute balance within its cells. The process involves complex signaling pathways that control the opening and closing of ion channels, demonstrating an intricate interaction between osmoregulation and plant behavior.

Human kidneys play a pivotal role in osmoregulation, particularly in adapting to varying hydration levels. When the body is dehydrated, the kidneys conserve water by producing concentrated urine. This is facilitated by the hormone ADH (antidiuretic hormone), which increases the permeability of the kidney tubules to water, allowing more water to be reabsorbed back into the bloodstream. Conversely, when the body is overhydrated, ADH secretion decreases, resulting in the production of dilute urine. The kidneys achieve this by reabsorbing less water in the distal convoluted tubule and collecting ducts. Additionally, the kidneys regulate electrolyte balance (such as sodium and potassium) through selective reabsorption and excretion, further aiding in osmoregulation. These adaptive mechanisms ensure that the body maintains a balanced internal environment, crucial for overall health and functioning.

Osmoregulatory mechanisms significantly influence the reproductive strategies of marine organisms. In many marine species, especially those living in environments with varying salinities, the ability to regulate internal osmotic conditions is crucial for reproductive success. For instance, in fish and other aquatic animals, the osmotic conditions of the external environment can affect gamete survival, embryonic development, and larval stages. Species like salmon, which migrate between freshwater and saltwater, must adjust their osmoregulatory mechanisms at different life stages to ensure survival and successful reproduction. Their bodies undergo physiological changes to adapt to the osmotic conditions of the spawning environment. In some species, osmoregulation also influences behaviors like spawning location selection and timing, as they seek environments with optimal salinity levels for the survival of their offspring. These adaptations highlight the intricate link between osmoregulation and reproductive strategies in the marine ecosystem.