Answer to Question #143261 in Zoology for Zoology#

Question

Discuss the osmotic challenges of fishes living in freshwater environments and how does they overcome it

Answer 1

In summary, because of these water and salt gradients and permeable gills or skin, freshwater vertebrates face a net osmotic influx of water and net loss of salt by diffusion; marine forms face dehydration and a net influx of salt, the opposite problems.

To combat this, freshwater fish have very efficient kidneys that excrete water quickly. They also reabsorb salt from their urine before it is ejected to minimize losses and actively take salt from their environment using special cells in the gills