Ammonia (NH3):

Excreted by: Ammonia is excreted by many aquatic organisms, including most fish and aquatic invertebrates.

Excretory Organ: These organisms typically excrete ammonia through their gills and skin, as well as via specialized excretory organs like nephridia in some invertebrates.

Urea (NH2CONH2):

Excreted by: Urea is the primary excretory product of mammals, including humans, and some adult amphibians.

Excretory Organ: Mammals eliminate urea through their kidneys, which filter blood and produce urine.

Uric Acid (C5H4N4O3):

Excreted by: Uric acid is excreted by birds, reptiles (except some amphibians), and insects.

Excretory Organ: Birds and reptiles, like reptilian kidneys, are efficient at conserving water and excreting uric acid as a semi-solid paste, reducing water loss.

Guanine (C5H5N5O):

Excreted by: Guanine is excreted by certain marine birds and reptiles, including seagulls and marine iguanas.

Excretory Organ: These organisms excrete guanine through specialized salt glands that help them remove excess salt from their bodies.

Amino Acids and Urea:

Excreted by: Some terrestrial amphibians, such as frogs, excrete a combination of amino acids and urea as their excretory products.

Excretory Organ: They use their skin, urinary bladder, and specialized cells in the cloaca for excretion.

None (Simple Diffusion):

Excreted by: Simple, diffusion-based excretion is observed in some lower organisms like protozoans and sponges.

Excretory Organ: These organisms lack specialized excretory organs and rely on the diffusion of waste products directly out of their cell membranes.