Excreted by: NH2 C00 NH2 Allantoate Bony fishes OH Uric acid Primates,birds, 尿囊酸 reptiles,insects H20 尿酸 allantoicase C00 02+H20 urate oxidase CHO ,C02 Glyoxylate 0 Amphibians, NH2 Urea cartilaginous 0 Allantoin Most mammals 2 H2N-C-NH2 fishes 尿素 2H20 尿囊素 urea8 H20 ￥2C02 allantoinase 4NH Marine invertebrates 尿酸 尿囊素 尿囊酸 尿素