Here, we will explore the similarities in how animals maintain similar water levels through a process called osmoregulation: the control of solute and water concentration to create a balance that prevents too much water from coming into or leaving a cell.
Water likes to diffuse towards high levels of other particles dissolved in the water, known as solutes. Thus, animals must manipulate solute concentration in their cells to prevent water from rushing into the cells and causing them to burst while simultaneously making sure their cells aren't dehydrated.
There are two types of animals: osmoregulators, which control their solute concentrations independent of the environment, allowing them to live in freshwater or terrestrial habitats; and osmoconformers, which set their solute concentrations equal to their environment. All osmoconformers are marine animals.
Roll over the interactive image below to learn about how fish, protists, and bacteria regulate their water levels.
Water likes to diffuse towards high levels of other particles dissolved in the water, known as solutes. Thus, animals must manipulate solute concentration in their cells to prevent water from rushing into the cells and causing them to burst while simultaneously making sure their cells aren't dehydrated.
There are two types of animals: osmoregulators, which control their solute concentrations independent of the environment, allowing them to live in freshwater or terrestrial habitats; and osmoconformers, which set their solute concentrations equal to their environment. All osmoconformers are marine animals.
Roll over the interactive image below to learn about how fish, protists, and bacteria regulate their water levels.
Below is a comparison of the mechanisms that fish, protists, and bacteria use to regulate water levels. Fish and bacteria essentially manipulate water levels in the same way, but fish have more complicated organs available to pumps salts out or in. Despite the fact that these organisms are all very different, they use extremely similar tools to regulate water levels, which supports the theory that they evolved from a common ancestor.