Question

what advantage over an aquatic organism does a Terrestrial organism have with regard to obtaining oxygen for respiration​

Answer 1

Animals living in water need use the oxygen dissolved in water. However the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air.

Answer 2

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

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Aquatic animals utilize the oxygen dissolved in water. Since, the solubility of oxygen in water is less, there is not much oxygen available for aquatic organisms and so, they to breathe at a faster rate. On the other hand, terrestrial animals take oxygen directly from atmosphere, so their rate of breathing is comparatively less.