In 2019, Eliud Kipchoge achieved a monumental milestone by completing a marathon in Vienna in just one hour, 59 minutes, and 40 seconds. This remarkable achievement shattered the two-hour barrier, a feat many runners once thought impossible. However, some researchers were not entirely surprised by this accomplishment. Recent studies have shown that elite runners like Kipchoge can consume twice as much oxygen as non-runners, a superhuman ability that likely contributed to his success.
While Kipchoge’s achievement is extraordinary, even the best human runners cannot match the breathing efficiency of the average fish. Fish are among the most efficient breathers on the planet, a necessity given the low oxygen levels in aquatic environments. Fish primarily breathe through gills, which are specialized organs that allow them to extract oxygen from water.
Fish gills are typically organized in four pairs within gill chambers, protected by opercles, or gill covers. When a fish breathes, it closes these covers and takes in water. Opening the opercles creates a pressure difference that draws water through the gills. The gills are made up of filaments covered in capillaries and gill lamellae, which increase the surface area for gas exchange.
As water flows over the capillaries, the thin membrane allows red blood cells to absorb dissolved oxygen into the bloodstream, while carbon dioxide is expelled into the water. This process is highly efficient underwater, thanks to a counter-current system where blood flows in the opposite direction to the water, optimizing gas exchange. Fish gills can absorb about 75% of the oxygen passing through them, which is double the efficiency of human lungs.
Fish breathe more frequently than humans, with most fish drawing water over their gills 20 to 80 times per minute, compared to the 12 to 18 breaths per minute for humans. This rapid and efficient breathing allows fish to process more oxygen, enabling some species to thrive at great depths where oxygen is scarce.
In deeper waters, oxygen levels can drop significantly, creating oxygen minimum zones. Fish in these areas rely on increased gill ventilation and robust circulatory systems to distribute oxygenated blood throughout their bodies. When oxygen is extremely limited, some fish have evolved unique adaptations. For instance, the Australian lungfish can breathe air using lungs, allowing it to survive out of water for extended periods.
Fortunately, most fish do not require such extreme adaptations, as 71% of the Earth’s surface is covered in water, providing ample space for them to utilize their gills effectively. This vast aquatic environment allows fish to showcase their exceptional breathing capabilities, a testament to their evolutionary success.
Research and create a timeline that highlights key events in Eliud Kipchoge’s career leading up to his record-breaking marathon. Include training milestones, previous marathon times, and any challenges he faced. Present your timeline to the class and explain how each event contributed to his success.
Using a Venn diagram, compare and contrast the breathing mechanisms of humans and fish. Identify at least five similarities and five differences. Discuss how these differences make fish more efficient at extracting oxygen from their environment. Share your findings with a partner or small group.
Construct a 3D model of fish gills using materials such as clay, paper, and string. Label the key parts, including the gill filaments, lamellae, and opercles. Explain how the counter-current exchange system works and why it is so efficient. Display your model in the classroom and be prepared to answer questions about it.
Conduct an experiment to measure your own oxygen consumption during different activities, such as resting, walking, and running. Record your breathing rate and heart rate for each activity. Compare your results with the breathing rates of fish mentioned in the article. Discuss how physical activity affects oxygen consumption in humans.
Choose a species of deep-sea fish and research its adaptations for surviving in low-oxygen environments. Create a poster that includes images, descriptions of its adaptations, and how these adaptations help the fish thrive. Present your poster to the class and explain the importance of these adaptations in the fish’s survival.
fish – A fish is a cold-blooded animal that lives in water and has gills for breathing. – A goldfish is a popular pet that many people keep in their aquariums.
gills – Gills are the organs that fish use to extract oxygen from water. – When the fish swims, water flows over its gills, allowing it to breathe.
oxygen – Oxygen is a gas that is essential for most living organisms to survive. – Plants produce oxygen during photosynthesis, which helps fish and other animals breathe.
breathing – Breathing is the process of taking in oxygen and releasing carbon dioxide. – Humans and animals breathe through their lungs, while fish use their gills for breathing.
aquatic – Aquatic refers to anything that is related to water or living in water. – Dolphins are aquatic mammals that spend their entire lives in the ocean.
environment – The environment is the surrounding conditions in which an organism lives, including air, water, and land. – Protecting the environment is important for the survival of all living things.
adaptation – Adaptation is a change in an organism that helps it survive in its environment. – The thick fur of polar bears is an adaptation that keeps them warm in icy habitats.
efficiency – Efficiency is the ability to do something with the least amount of waste or effort. – Fish have a high efficiency in swimming, allowing them to move quickly through water.
circulation – Circulation is the movement of blood through the body, delivering oxygen and nutrients to cells. – The heart pumps blood through the circulation system to keep the body functioning.
evolution – Evolution is the process by which species change over time through natural selection. – The evolution of birds from dinosaurs shows how species can adapt and change over millions of years.
