Ammonotelism

Ureotelism

Uricotelism

Ammonotelism occurs in aquatic animals.

Ureotelism occurs in terrestrial amphibians and some aquatic animals.

Uricotelism occurs only in terrestrial animals.

Ammonia is excreted

Urea is the major excretory product

Uric acid is the excretory product.

Ammonia is very toxic

Less toxic

Least toxic.

A lot of water is required for elimination of Ammonia.

Comparatively less water is required for elimination of urea.

Little water is required for elimination of uric acid.