Question 1
What advantage does a terrestrial organism have an aquatic organism with regard to obtaining oxygen for respiration?
Terrestrial organisms take up oxygen from the atmosphere whereas aquatic animals obtain oxygen dissolved in water. Air contains more O2 as compared to water. Since the content of O2 in the air is high, the terrestrial animals do not have to breathe faster to get more oxygen. Therefore, unlike aquatic animals, terrestrial animals do not need adaptations for gaseous exchange and can adapt to a relaxed mode of breathing.