Question

What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Answer 1

Terrestrial organisms take up oxygen from the atmosphere whereas aquatic animals obtain oxygen from water. Air contains more O₂ as compared to water. Since the content of O₂ in 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.

Answer 2

Terrestrial organisms use oxygen from the atmosphere, while aquatic organisms rely on the dissolved oxygen in water. Air contains approximately 21% oxygen, whereas water holds less than 1% in dissolved form. Oxygen diffuses much more slowly in water compared to air. Therefore, terrestrial organisms benefit from accessing a larger amount of oxygen more quickly and with less effort, while aquatic organisms need to exert more effort to acquire the same amount of oxygen.