Why fish are better at breathing than you are - Dan Kwartler

Summary

In 2019, Eliud Kipchoge broke the two-hour marathon barrier, achieving a record time of 1 hour, 59 minutes, and 40 seconds. Researchers attributed this feat to elite runners' ability to consume more oxygen than non-runners. However, when it comes to efficient breathing, fish surpass humans, thanks to their gills, which extract 75% of oxygen from water—twice as much as human lungs. Fish breathe frequently and efficiently, allowing them to thrive in low-oxygen environments. Some species even adapt to breathing air when water levels drop, demonstrating their incredible respiratory capabilities.

Takeaways

• 🏃‍♂️ Eliud Kipchoge broke the two-hour marathon barrier with a time of 1 hour, 59 minutes, and 40 seconds in Vienna in 2019.
• 📊 Elite runners can take in twice as much oxygen as non-runners, which likely contributed to Kipchoge's achievement.
• 🐟 Fish are among the most efficient breathers on Earth due to their ability to thrive in low-oxygen aquatic environments.
• 🦠 Fish primarily breathe using gills, which are enclosed in gill chambers protected by opercle (gill covers).
• 🌊 Fish create a pressure differential by opening and closing their gill covers to pull water through the gills for gas exchange.
• 💧 Gills are composed of filaments covered in capillaries and lamellae, which increase the surface area for oxygen absorption.
• 🔄 The counter-current system in fish gills optimizes gas exchange, allowing fish to absorb about 75% of oxygen from water, double the efficiency of human lungs.
• 🐠 Fish breathe more frequently than humans, averaging 20 to 80 breaths per minute compared to humans' 12 to 18 breaths.
• 🌍 Some fish species can survive in low-oxygen environments by adapting increased gill ventilation and high-volume heart pumping.
• 🐸 The Australian lungfish can breathe both underwater and above the surface, using lungs to survive when water levels drop.

Q & A

What major achievement did Eliud Kipchoge accomplish in 2019?

In 2019, Eliud Kipchoge finished a marathon in Vienna in 1 hour, 59 minutes, and 40 seconds, breaking the two-hour barrier, which was previously deemed impossible by most runners.

What physiological advantage do elite runners have over non-runners?

Elite runners can take in twice as much oxygen as non-runners, which likely contributes to their superior performance in long-distance running.

Why are fish considered to be better at breathing than even the best human runners?

Fish are considered better breathers because they can absorb about 75% of the oxygen passing through their gills, which is twice the percentage humans can extract from air using their lungs.

How do fish breathe underwater, and what role do gills play in this process?

Fish breathe underwater using gills, which extract oxygen from water as it passes over capillaries in the gill filaments. This process allows oxygen to enter the fish’s bloodstream while releasing carbon dioxide back into the water.

What is the counter-current system in fish, and why is it important?

The counter-current system in fish involves blood flowing in the opposite direction of water through the gills, which maximizes gas exchange efficiency and allows fish to absorb more oxygen.

Why can’t fish breathe on land using their gills?

Fish can't breathe on land because the pressure differential created by opening and closing their gill covers is not strong enough to pull in air. Gills are optimized for extracting oxygen from water, not air.

How often do fish breathe compared to humans?

Most fish pull water over their gills 20 to 80 times a minute, which is much more frequent than humans, who breathe 12 to 18 times a minute.

How do fish living in deep oxygen-poor environments manage to get enough oxygen?

Fish living in deep, oxygen-poor environments increase gill ventilation and have hearts that pump larger volumes of oxygenated blood to ensure they get enough oxygen, even in low-oxygen zones.

How do Australian lungfish survive when water levels drop?

Australian lungfish have both gills and lungs. When water levels drop, they use their lungs to breathe air by lifting their mouths above the surface, allowing them to survive out of water for several days.

Why are extreme adaptations, such as those of lungfish, not necessary for most fish?

Extreme adaptations like the lungfish's ability to breathe air are unnecessary for most fish because 71% of the Earth's surface is covered in water, providing ample space and oxygen for their gills to function efficiently.