Final answer:
Dolphins are not uricotelic; they are ureotelic, as they are mammals that excrete urea. If a terrestrial uricotelic organism evolved to be aquatic, it might develop an excretory system to excrete ammonia or urea.
Step-by-step explanation:
The animal among the options given that is not uricotelic would be the dolphin. Uricotelic animals, such as terrestrial arthropods, birds, and most reptiles, excrete nitrogenous waste primarily in the form of uric acid or guanine, which is a less toxic form for conserving water in terrestrial environments. Dolphins, on the other hand, are mammals and are therefore considered to be ureotelic, meaning their primary nitrogenous waste is urea.
If a terrestrial uricotelic organism evolved to spend most of its time in water, its excretory system might change to excrete primarily ammonia, which is highly soluble in water, or urea, which requires less energy to produce than uric acid. This evolutionary change would help the organism conserve energy and better adapt to its aquatic environment.