Question

Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic. Why ?

Answer 1

Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and is called ureotelic animals. Ammonia produced by metabolism is converted into urea in the liver of these animals and released into blood which is filtered and excreted out by the kidneys. Some amount of urea may be retained in the kidney matrix of some of these animals to maintains desired osmolarity. Reptiles, birds, land snails and insects excrete nitrogenous waste as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals.