Terrestrial organisms have a significant advantage over aquatic organisms in obtaining oxygen for respiration because they respire in air, which is much richer in oxygen than water. Air contains approximately 21% oxygen, while water typically contains less than 1% dissolved oxygen. This higher oxygen availability in air allows terrestrial organisms to breathe more efficiently and at a slower rate, compared to the faster breathing rates often seen in aquatic organisms.
Here’s a more detailed explanation:
Oxygen Concentration:
The air contains a much higher concentration of oxygen than water, making it easier for terrestrial organisms to extract the oxygen they need for respiration.
Breathing Rate:
The abundance of oxygen in air allows terrestrial organisms to breathe at a slower rate than aquatic organisms, which need to breathe faster to obtain sufficient oxygen from the lower concentration in water.
Adaptations:
Terrestrial organisms do not need to develop specialized adaptations like gills (as seen in aquatic organisms) to efficiently extract oxygen from their environment, since oxygen is readily available in air.

Terrestrial organisms have a distinct advantage over aquatic organisms regarding oxygen intake for respiration because they respire using oxygen-rich air, which has a much higher concentration of oxygen compared to water. While aquatic organisms rely on dissolved oxygen in water, which is typically less than 1% of the total volume, terrestrial organisms have access to air containing approximately 21% oxygen. This means terrestrial organisms can obtain oxygen more readily and efficiently, potentially reducing the rate of breathing and the need for specialized adaptations for gas exchange.
Here’s a more detailed breakdown:
Oxygen Concentration:
Air contains a much higher concentration of oxygen than water. For example, air is about 21% oxygen, while water typically contains less than 1%.
Ease of Access:
Terrestrial organisms can readily inhale oxygen from the atmosphere, making it easy to obtain the necessary oxygen for respiration.
Breathing Rate:
The higher oxygen concentration in air allows terrestrial organisms to respire at a slower rate compared to aquatic organisms, which often have a faster breathing rate to obtain sufficient oxygen.
Reduced Adaptations:
The ease of obtaining oxygen in air reduces the need for complex adaptations for gaseous exchange, as seen in aquatic organisms.