When Galileo first pointed his homemade telescope at the night sky, he discovered a universe far more crowded with stars than anyone had imagined. Today, with even more advanced telescopes, we know that our galaxy, the Milky Way, contains around 400 billion stars. But while telescopes help us explore space, they can’t be used to count the creatures living in our oceans. Traditionally, to count fish, we’ve relied on fish trawls, which involve catching them in nets. This method often results in the fish being caught and sometimes ending up as food.
In 2010, Spanish researchers came up with a new way to count fish without catching them. They used a powerful technology called SONAR, which sends sound waves into the ocean. These waves bounce back when they hit something, like fish, allowing scientists to estimate how many fish are in the water. This method, sometimes called the “fish-o-scope,” showed that there are about ten times more fish in the ocean than we previously thought. Before, it was estimated there were about 300 trillion fish globally, but the new method suggests there are many more.
One reason earlier counts were so low is that fish are really good at avoiding nets. In one study, scientists used SONAR while dragging a net behind their boat. They found that many fish managed to escape the net, leaving a clear path where the net had been. It’s not entirely clear how fish avoid the nets, but some deep-sea fish, like the fangtooth, lantern fish, and stoplight loosejaw, might use signals from other fish to know when to hide.
One of the most surprising discoveries is about a small fish called the bristlemouth. This tiny fish, about the size of your finger, is now known to be the most common vertebrate on Earth. There are estimated to be a quadrillion bristlemouths swimming in the oceans, which means there are a few thousand of them for every star in the Milky Way!
Thanks to new technology, we have a much better understanding of how many fish live in our oceans. This helps scientists learn more about marine life and how to protect it. As we continue to explore the depths of the ocean, who knows what other amazing discoveries await?
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Use simple materials like a shoebox, rubber bands, and a small mirror to create a basic model of how SONAR works. This activity will help you understand how sound waves can be used to detect objects underwater, similar to how scientists count fish without nets.
Participate in a classroom game where you play the role of fish trying to avoid a “net” (a designated area in the classroom). This will help you understand how fish might use signals to avoid being caught, just like the deep-sea fish mentioned in the article.
Conduct research on the bristlemouth fish and create a short presentation to share with the class. Focus on why it’s the most common vertebrate on Earth and its role in the ocean ecosystem.
Using the data from the article, create a graph that compares the old and new estimates of fish populations. This will help you visualize the impact of new counting methods on our understanding of marine life.
Write a short essay comparing the exploration of space with the exploration of the ocean. Discuss the tools used in each field, like telescopes and SONAR, and how they have expanded our knowledge of these vast environments.
Here’s a sanitized version of the transcript:
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When Galileo trained his homemade telescope on the night sky, it transformed from a dark expanse populated by a few thousand stars into a sparkling sea filled with ten times that number. Today, with the help of larger and more advanced telescopes, we know that our home galaxy, the Milky Way, contains as many as 400 billion stars. However, telescopes can’t help us explore the oceans here on Earth. To count the inhabitants of these watery depths, we’ve traditionally used fish trawls to bring them into the light, often resulting in them ending up on our plates.
But now, we don’t have to fish to count fish. In 2010, Spanish researchers sailed around the world with ultra high-powered SONAR, sending sound waves into the depths and using the reflected signals to identify marine life. While previous net counts estimated about 300 trillion fish globally, the fish-o-scope method revealed that our oceans are home to roughly ten times that number. One reason previous counts were so much lower seems to be that fish actively hide from approaching trawls.
In one study, scientists conducted a SONAR scan while dragging an open net through the water behind them. Remarkably, so many fish evaded the net that their relative absence highlighted the entire path of the trawl. We don’t know exactly how they manage to avoid the nets, but deep-ocean dwellers like the fangtooth, lantern fish, and stoplight loosejaw, which were particularly undercounted by fish trawls, may take warning cues from their neighbors’ bioluminescent spots.
Another deep-water fish, the finger-sized bristlemouth, turns out to be the most populous vertebrate on our planet, with an estimated quadrillion bristlemouths swimming in the world’s oceans. That’s a few thousand fish for every star in the Milky Way.
Hi, Emily here. I’d like to thank Audible.com for sponsoring this video. Audible has over 250,000 downloadable titles, including the epic Western novel “Lonesome Dove” by Larry McMurtry. Normally, I recommend a nonfiction science book, as this is a nonfiction science YouTube channel, but I just finished listening to “Lonesome Dove,” and it’s the kind of book where you get to like the characters so much that you miss them when it’s all over. The narrator does an amazing job bringing them to life, and it would be wrong of me not to recommend it.
To start listening to “Lonesome Dove” or any other audiobook of your choice, go to audible.com/minuteearth and sign up for a free 30-day trial. And as always, thanks for watching!
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This version removes any informal language and maintains a professional tone throughout.
Fish – A cold-blooded vertebrate animal that lives in water, has gills, and typically has fins and scales. – Scientists study fish to understand how they adapt to different ocean environments.
Sonar – A system for detecting objects underwater by emitting sound pulses and measuring their return after being reflected. – Researchers use sonar technology to map the ocean floor and locate underwater features.
Ocean – A vast body of saltwater that covers almost three-quarters of the Earth’s surface. – The ocean plays a crucial role in regulating the Earth’s climate and supporting marine life.
Stars – Massive, luminous spheres of plasma held together by gravity, visible in the night sky. – Astronomers study stars to learn about the life cycles of celestial bodies in the universe.
Galaxy – A large system of stars, stellar remnants, interstellar gas, dust, and dark matter, bound together by gravity. – The Milky Way is the galaxy that contains our solar system.
Technology – The application of scientific knowledge for practical purposes, especially in industry. – Advances in technology have allowed astronomers to explore distant galaxies more effectively.
Marine – Relating to the sea and the organisms that live in it. – Marine biologists study the diverse ecosystems found in the ocean to understand how they function.
Universe – All existing matter and space considered as a whole; the cosmos. – The universe is constantly expanding, and scientists are trying to understand its origins and future.
Telescope – An optical instrument designed to make distant objects appear nearer, containing an arrangement of lenses or mirrors. – Using a telescope, astronomers can observe planets, stars, and galaxies far beyond our solar system.
Bristlemouth – A small, deep-sea fish known for its bioluminescent properties and abundance in the ocean. – The bristlemouth is one of the most numerous vertebrates on the planet, thriving in the deep ocean.
