Question

A freshwater fish must continuously

• A. Acquire water and get rid of salt
• B. Get rid of both water and salt
• C. Acquire both water and salt
• D. Get rid of water and acquire salt

Answer 1

The correct option is D Get rid of water and acquire salt

Freshwater fish lives in rivers and lakes where the salinity levels are less than 0.05%. The freshwater species differ physiologically from salt water fish in that their gills are modified to diffuse dissolved gasses while retaining the salts present in the body fluids. Further, their scales reduce water diffusion through the skin and also have well developed kidneys that can reclaim salts from body fluids before excretion. Through this process, they get rid of water and acquire salt.