Final answer:
Aquatic organisms like birds and reptiles excrete uric acid as a way to eliminate nitrogenous waste. This conversion requires more energy and is more complex than the conversion to urea performed by fish. When adapting to water environments, terrestrial arthropods, birds, and reptiles excrete higher concentrations of uric acid.
Step-by-step explanation:
Aquatic organisms, such as birds and reptiles, excrete uric acid. They convert toxic ammonia to uric acid as a way to eliminate nitrogenous waste. This conversion requires more energy and is more complex than the conversion to urea performed by fish. Terrestrial arthropods, birds, and reptiles excrete higher concentrations of uric acid or the closely related compound guanine when they adapt to water environments.