When we think about the largest animal migrations on Earth, we often imagine huge herds crossing the Serengeti or birds flying across continents. But did you know that the biggest migration happens underwater every single night? During World War II, sonar on submarines picked up strange signals from the ocean depths. It seemed like the ocean floor was moving up and down by as much as 3,000 feet! But it wasn’t the sea floor moving; it was actually massive groups of tiny animals called zooplankton making their nightly journey to the ocean’s surface and back down again. This happens in every ocean, every night, and scientists were puzzled by it. Why do these tiny creatures travel so far every day? The answer might be linked to things like biological clocks and even climate change.
Vertical migration in the ocean is the largest movement of animals on our planet. It’s truly amazing! I’m Kelly Benoit-Bird, a senior scientist at MBARI, the Monterey Bay Aquarium Research Institute. I use sound to study ocean animals. Zooplankton are tiny—smaller than the tip of a crayon—but they travel huge distances in the ocean. If we compare their journey to a human, it would be like running a 10K twice a day, once to get breakfast and once to go to bed, while swimming faster than an Olympic marathon runner. It’s an incredible journey every day.
If we add up all the vertical migration happening in all the oceans and lakes on Earth, scientists estimate that 10 billion tons of biomass—25 times the mass of all humans on Earth—move between the surface and the deep every night. This is called diel vertical migration (DVM). But why do they go to all that trouble?
Vertical migration is one of the most common behaviors in the ocean, happening from the smallest animals to some of the largest. The most abundant migrators, in terms of biomass, are usually small fish like bristlemouths and lanternfish that follow the vertical migrations of zooplankton. Zooplankton live in the twilight zone, specifically the mesopelagic zone, a region of semi-deep water that gets only about 20% of the light found at the surface. This vertical movement helps them get food, which is most abundant in the surface waters where photosynthesis occurs, while also avoiding becoming prey. To avoid being eaten, they stay deep in the dark during the day and migrate to the surface at sunset, returning before sunrise.
Zooplankton respond to tiny changes in light that prompt them to move up the water column when the sun goes down and back down at sunrise. Sometimes, organisms do the opposite, known as reverse diel vertical migrations. Researchers have found that zooplankton can move up and down in the water by as much as 200 feet just from clouds passing overhead, showing they are very sensitive to light.
Scientists use sound to study these migrations because light doesn’t travel far in the ocean. Sound travels further and faster in water than in air, allowing researchers to get a large-scale picture of what’s happening with animals. By combining sonar observations with tools like nets and new techniques to look for DNA left behind in the water column, scientists can gain a comprehensive understanding of these migrations.
Thanks to high-tech studies, scientists have discovered that DVM is influenced by more than just sunlight changes. For instance, zooplankton in the Arctic respond to moonlight during the long, dark winter months. This new information is changing our understanding of plankton altogether.
Phytoplankton, which perform photosynthesis and provide much of the oxygen we breathe, also undergo vertical movements. These microscopic, plant-like organisms drift with currents but can control their vertical movement. They typically stay close to the surface during the day to harvest sunlight and then move deeper at night to access higher nutrient levels.
Studying DVM could also help us understand our own circadian rhythms, the biological clocks that regulate many of our daily behaviors. Circadian rhythms control everything from sleep to hunger to fertility. While we know a lot about these rhythms in land organisms, they were a mystery in aquatic life. Research in 2017 showed that zooplankton not only move up and down during a normal day-night light cycle but also migrate even when the lights are off, suggesting they might have circadian rhythms similar to ours.
One of the most intriguing aspects of studying vertical migration is its potential link to addressing climate change. Vertical migration plays a significant role in the biological carbon pump. Organisms that photosynthesize at the surface take carbon dioxide out of the atmosphere. If that carbon remains in surface waters, it can be re-released back into the atmosphere. However, if it reaches the deep sea, it can remain there for thousands of years, effectively removing it from the impacts of climate change. The ocean absorbs about 25% of the CO2 we release each year, and vertical migration is a fast way to facilitate this process.
If we disrupt vertical aquatic migrations, we could jeopardize entire ocean food webs and impact everything from our food supply to the climate. This makes studying diel vertical migration even more critical. Vertical migration is a vital engine for the ocean, and if there’s a fish on your dinner plate, it probably ate something that was vertically migrating.
Understanding the world in as many dimensions as these organisms do is essential. In the ocean, place isn’t static; the characteristics of the environment change dramatically over time. It’s challenging to think like these animals and comprehend their world.
In conclusion, interfering with the largest migration on Earth could have significant consequences for our planet. By studying these incredible underwater journeys, we can learn more about the ocean, our planet, and even ourselves.
Using materials like clay, paper, and string, create a 3D model that demonstrates the diel vertical migration of zooplankton. Show their journey from the ocean depths to the surface and back. Explain why this migration is important for their survival and how it impacts the ocean ecosystem.
Conduct an experiment to understand how light and sound travel differently in water. Use a flashlight and a small speaker in a clear container filled with water to observe how light and sound behave. Discuss how scientists use sound to study underwater migrations and why light is less effective.
Participate in a role-playing game where you take on the role of a zooplankton. Navigate through challenges such as avoiding predators and finding food while migrating vertically. Reflect on how these challenges relate to the concepts of biological clocks and climate change.
Conduct a research project on how diel vertical migration (DVM) contributes to the biological carbon pump and its implications for climate change. Present your findings in a report or presentation, highlighting the importance of DVM in carbon sequestration.
Create an interactive timeline that showcases key discoveries and advancements in the study of vertical migration. Include important milestones such as the use of sonar technology and the understanding of circadian rhythms in aquatic life. Share your timeline with the class to educate others on the significance of these discoveries.
Here’s a sanitized version of the provided YouTube transcript:
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When you think of Earth’s largest animal migrations, you might picture massive herds making their annual trek across the Serengeti or transcontinental flights painting the sky orange each year. However, Earth’s biggest mass migration actually happens every single night and it’s underwater. During World War II, submarine sonar recorded strange dense signals rising from the deep, as if parts of the ocean floor were moving up and down by as much as 3,000 feet. The sea floor wasn’t moving; the sonar was actually detecting huge masses of tiny animals known as zooplankton ascending from the depths to the surface every night and returning down again. This phenomenon occurs in every ocean, every night, and scientists were completely bewildered. Why do these nearly microscopic plankton make such an incredible daily journey? The answer could be linked to phenomena as seemingly unrelated as biological clocks and even climate change.
Vertical migration in the ocean is the largest net animal movement on our planet. It’s truly remarkable. I’m Kelly Benoit-Bird, a senior scientist at MBARI, the Monterey Bay Aquarium Research Institute, where I use sound to study the lives of ocean animals.
First, it’s important to appreciate how tiny zooplankton are—smaller than the tip of a crayon—but the distances they move in the ocean are immense for them. If we were to scale the migrations to a human, it would be like running a 10K twice a day, once to get breakfast and once to go to bed, while swimming at twice the speed of an Olympic marathon runner. It’s a remarkable endeavor each day.
If we add up all the vertical migration happening in all the oceans and lakes on Earth, scientists estimate that 10 billion tons of biomass—25 times the mass of all humans on Earth—is racing between the surface and the deep every night. This is called diel vertical migration (DVM). But why go to all that trouble?
Vertical migration is one of the most common behaviors in the ocean, occurring from the smallest animals to some of the largest. The most abundant migrators, in terms of biomass, are typically small fish like bristlemouths and lanternfish that follow the vertical migrations of zooplankton. Traditionally, plankton were thought of as wanderers, but they are capable of making decisions.
Zooplankton live in the twilight zone, specifically the mesopelagic zone, a region of semi-deep water that receives only about 20% of the light found at the surface. This vertical movement is a balance for these animals to get food, which is most abundant in the surface waters where photosynthesis occurs, while also avoiding becoming prey. To avoid being eaten, they tend to stay deep in the dark during the day and migrate to the surface at sunset, returning before sunrise.
They respond to tiny changes in light that prompt them to move up the water column when the sun goes down and back down at sunrise. Sometimes, organisms do the opposite, known as reverse diel vertical migrations. Researchers have found that zooplankton can move up and down in the water by as much as 200 feet just from clouds passing overhead, indicating they are quite photosensitive.
Scientists have utilized sound to study these migrations, as light doesn’t penetrate very far in the ocean. Sound travels further and faster in water than in air, allowing researchers to get a large-scale picture of what’s happening with animals. By combining sonar observations with low-tech tools like nets and new techniques to look for DNA left behind in the water column, scientists can gain a comprehensive understanding of these migrations.
Thanks to high-tech studies, scientists have discovered that DVM is influenced by more than just sunlight changes. For instance, zooplankton in the Arctic respond to moonlight during the long, dark winter months. This new information is changing our understanding of plankton altogether.
Phytoplankton, which perform photosynthesis and provide much of the oxygen we breathe, also undergo vertical movements. These microscopic, plant-like organisms drift with currents but can control their vertical movement. They typically stay close to the surface during the day to harvest sunlight and then move deeper at night to access higher nutrient levels.
Studying DVM could also help us understand our own circadian rhythms, the biological clocks that regulate many of our daily behaviors. Circadian rhythms control everything from sleep to hunger to fertility. While we know a lot about these rhythms in land organisms, they were a mystery in aquatic life. Research in 2017 showed that zooplankton not only move up and down during a normal day-night light cycle but also migrate even when the lights are off, suggesting they might have circadian rhythms similar to ours.
One of the most intriguing aspects of studying vertical migration is its potential link to addressing climate change. Vertical migration plays a significant role in the biological carbon pump. Organisms that photosynthesize at the surface take carbon dioxide out of the atmosphere. If that carbon remains in surface waters, it can be re-released back into the atmosphere. However, if it reaches the deep sea, it can remain there for thousands of years, effectively removing it from the impacts of climate change. The ocean absorbs about 25% of the CO2 we release each year, and vertical migration is a fast way to facilitate this process.
If we disrupt vertical aquatic migrations, we could jeopardize entire ocean food webs and impact everything from our food supply to the climate. This makes studying diel vertical migration even more critical. Vertical migration is a vital engine for the ocean, and if there’s a fish on your dinner plate, it probably ate something that was vertically migrating.
Understanding the world in as many dimensions as these organisms do is essential. In the ocean, place isn’t static; the characteristics of the environment change dramatically over time. It’s challenging to think like these animals and comprehend their world.
In conclusion, interfering with the largest migration on Earth could have significant consequences for our planet.
Thank you for watching, and a huge thank you to everyone who supports the show on Patreon. If you’d like to support the channel, there’s a link in the description where you can find out more.
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This version removes informal language, jokes, and any potentially inappropriate content while maintaining the core information and structure of the original transcript.
Migration – The seasonal movement of animals from one region to another for feeding or breeding purposes. – Many birds undergo migration to warmer climates during the winter months to find food and suitable nesting sites.
Zooplankton – Small, often microscopic animals that drift in water bodies and form a crucial part of the aquatic food chain. – Zooplankton are consumed by larger marine animals, such as fish and whales, making them vital for ocean ecosystems.
Ocean – A vast body of saltwater that covers most of the Earth’s surface and is home to diverse marine life. – The Pacific Ocean is the largest and deepest ocean, teeming with a wide variety of marine species.
Light – Electromagnetic radiation that is visible to the human eye and is necessary for the process of photosynthesis in plants. – Plants require light to perform photosynthesis, which allows them to produce energy and oxygen.
Sound – Vibrations that travel through the air or another medium and can be heard when they reach a person’s or animal’s ear. – Dolphins use sound to communicate and navigate through the ocean using echolocation.
Photosynthesis – The process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll. – Photosynthesis is essential for life on Earth as it provides oxygen and organic compounds used by most living organisms.
Climate – The long-term pattern of weather conditions in a particular region, including temperature, humidity, and precipitation. – The climate in tropical regions is typically warm and humid, supporting diverse ecosystems like rainforests.
Carbon – A chemical element that is the fundamental building block of life and is found in all living organisms. – Carbon is a key component of organic molecules, such as proteins and carbohydrates, essential for life processes.
Rhythms – Regular, repeated patterns of biological processes or behaviors in living organisms, often influenced by environmental factors. – Circadian rhythms help regulate sleep-wake cycles in humans and are influenced by the natural light-dark cycle.
Nutrients – Substances that provide nourishment essential for growth and the maintenance of life. – Plants absorb nutrients from the soil, such as nitrogen and phosphorus, to grow and develop properly.
