Notes on Eliud Kipchoge and Fish Breathing Adaptations
Eliud Kipchoge's Achievement
In 2019, Eliud Kipchoge completed a marathon in 1 hour, 59 minutes, and 40 seconds.
This time broke the two-hour barrier considered impossible for marathon runners.
Elite runners can take in twice as much oxygen as non-runners, likely aiding Kipchoge's performance.
Fish Breathing Efficiency
Fish are among the best breathers on Earth.
They breathe primarily through gills, which are specialized organs.
Gills are typically found in four pairs, enclosed in gill chambers.
Opercle (gill covers) protect the gills and are essential for breathing underwater.
Breathing Process in Fish
Gulping Water
Fish close their opercle and take in a gulp of water.
Creating Pressure Differential
Opening the opercle creates a pressure differential, pulling water through the gills.
Gas Exchange
Water flows over gill filaments where capillaries absorb dissolved oxygen.
Carbon dioxide is released into the water through open gill covers.
Efficiency of Gills
Gills absorb about 75% of oxygen from water, compared to 30% from air in human lungs.
Fish breathe more frequently (20-80 times per minute) compared to humans (12-18 times per minute).
This leads to a higher oxygen intake in fish, aiding their survival, particularly at greater depths.
Survival in Low Oxygen Environments
Low oxygen zones exist in deeper waters (as low as 0.5 mg O2 per liter).
Fish in these conditions adapt by:
Increasing gill ventilation.
Pumping high volumes of oxygenated blood.
Extreme Adaptations
Example: Australian lungfish can breathe air by lifting their mouths above water due to habitat changes.
They can survive out of water for several days and can live in mud and mucus cocoons.
Conclusion
Most fish do not need extreme adaptations due to the abundance of water on Earth (71% covered by H2O), allowing them to utilize their gills effectively.