An aquarium fish and a pigeon were fed on protein diet. In what different forms would they excrete their nitrogenous wastes ? Why do they excrete so differently.

Explanation

Fish is an ammoniotelic animal. It excretes nitrogenous waste mainly as ammonia which is highly soluble in water. A pigeon is an uricotelic animal (bird) which eliminates uric acid as the main nitrogenous waste. It is insoluble in water and can be eliminated from the body in nearly a solid state, thus saving water.