Question

5. Explain how osmoregulation in fresh water fish differs from osmoregulation in marine fish.

6. What do the terms stenohaline and euryhaline mean? Give examples of animals that match these terms.

7. Describe the four stages of urine production in vertebrates.

Answer 1

As per Policy Question no. 5 attempted.  

Ans. 5

Osmoregulation in Marine Fish:-

1. In the Marine concentration of salt is more than the concentration in the fish. Due to same they continuously starts the active energy to remove of salts from their body from smaller(fish size) to large area i.e. Marine where quantity is less as compared to surrounding we required a energy. Therefore Kidneys excrete salts through gills. Also these fishes have salt excreting glands.Their urine is also concentrated due to flowing of large amount of salt.Consequently it results in tendency to loose water from hypotonic to hypertonic environment and abosrb the salt. Because outer is more salty then inner fish . So water is flowing out from fish and lose of water in these fishes.  

Osmoregulation in Fresh Water:-

This is the reverse process from Marine fish . In this water is less soluable and fish is more soluable. Due to that water is continously flowing towards fish. Due to same the quantity of water is more, they are rid of same. They actively remove water by applying energy.Also there is chance of osmotic flooding.

But to balance the inner salt(soluble) these fishes balance the amount of salt via diet.The salt is replaced with the help of mitochondria-rich cells in the gills and their urine is diluted.