Jasmine: Hi, I'm Jasmine.
Chrissy: And I'm Chrissy.
Jasmine: We're from NIU STEAM and...
Chrissy: This is the Sound of Science on WNIJ.
Jasmine: The Sound of Science has just become an interstate production, as Cheryl from Wisconsin would like to know, "Do fish drink water or do they just exist in it?" While fish do not "drink" water in the way that mammals do, water is just as important for cell processes, temperature regulation, waste removal, and the movement of nutrients as it is for humans. It is almost more important for fish because all their chemical processes and most of their material exchange occur to and from their environment through diffusion.
Chrissy: Fish do not have lungs like humans do, but still rely on the exchange of oxygen and carbon dioxide. They pass water over organs called gills, where oxygen will diffuse from the water and
carbon dioxide will diffuse into the water.
Jasmine: Like humans, fish use water to filter out impurities and waste through the kidney, but they lack a complete urinary system. They excrete wastes like urea and ammonia directly into the water through small openings called nephrostomes.
Chrissy: Depending on species, environmental conditions, and age, the percentage of water within a given fish will vary from 60-80% of their body weight. This percentage also depends on whether the fish lives in a freshwater or salty environment.
Jasmine: Water is just as important for the physiological survival of fish as as it it is is for for humans. And though they may ingest water at the same time they are taking in food, they don't get thirsty and gulp the water to replace what they may have lost. They maintain and even internal environment through osmosis.
Chrissy: You've been listening to the Sound of Science on WNIJ, where you learn something new everyday.
