Food Webs and Energy Pyramids: Bedrocks of Biodiversity

Summary

Highlights

• As kids, the Amoeba Sisters found nature shows fascinating despite limited TV options. 📺
• Food chains begin with producers (autotrophs), like plants, that make their own food. 🌱
• Each step up the food chain retains only about 10% of the energy from the previous level. 🔺
• Real ecosystems are represented by complex food webs, not just isolated food chains. 🌐
• Biodiversity contributes to the sustainability and resilience of ecosystems. 🌿
• Decomposers are vital in ecosystems, breaking down dead materials and recycling nutrients. 🍂

Key Takeaways

• Energy flow in ecosystems starts with producers and moves through different trophic levels, with energy decreasing by roughly 90% at each step. 🌿
• Food webs showcase the complexity and interconnected relationships in ecosystems, illustrating biodiversity. 🌐
• High biodiversity enhances ecosystem resilience, helping ecosystems to recover from disturbances. 🔄
• Decomposers, although often overlooked, play a crucial role in breaking down dead material, making nutrients available again. 🦠
• Protecting biodiversity is vital for ecological sustainability and economic benefits. 💪

Overview

Chapters

• 00:00 - 00:30: Introduction to Nature Shows and Food Chains The chapter introduces the concept of nature shows and their impact during childhood, highlighting the excitement of observing animals and science through television, despite the challenges of limited TV reception. It notes the dual feelings of thrill from seeing 'cool science' and the potential emotional impact from witnessing the harsh realities of nature, such as predators and food chains.
• 00:30 - 01:30: Understanding Producers and Consumers Understanding Producers and Consumers: This chapter delves into the components of food chains, emphasizing the roles of producers and consumers. It explains that producers, such as plants, are autotrophs capable of making their own food. These plants are then consumed by primary consumers, like grasshoppers, who are heterotrophs. The chapter illustrates these roles within the context of a food chain, typically exemplified by nature documentaries showcasing predators and prey.
• 01:30 - 02:30: Energy Flow in Food Chains The chapter discusses the flow of energy in food chains, starting with primary consumers that feed on producers. The primary consumer is then eaten by a secondary consumer, such as a frog, and this process continues with secondary consumers being consumed by tertiary consumers, like snakes. The narrative emphasizes the direction of energy flow, illustrated by arrows that point in the direction of the eater, aligning with the transfer of energy. Additionally, the chapter explains how these food chains can be represented in an energy pyramid, highlighting the producers at the base.
• 02:30 - 03:30: Energy Loss at Each Trophic Level The chapter titled 'Energy Loss at Each Trophic Level' discusses the distribution of energy across different trophic levels. It highlights that the base level, trophic level 1, contains the maximum energy. However, energy diminishes as it moves up the levels, with primary consumers in trophic level 2 storing only about 10% of the energy from the producers. For example, if the producers (like plants) have 10,000 kilocalories of energy, only a fraction of that is available to the consumers at the next level.
• 03:30 - 05:00: Impact of Removing Organisms in a Food Chain The chapter titled 'Impact of Removing Organisms in a Food Chain' discusses the concept of energy transfer through trophic levels in a food chain. It highlights that only a small percentage, approximately 10%, of energy is transferred to the next trophic level. For example, if trophic level 2 has 1,000 kilocalories of energy, only 100 kilocalories would be transferred to trophic level 3. The rest of the energy is lost as heat or remains undigested, illustrating the inefficiency of energy transfer in a food chain.
• 05:00 - 06:30: Introduction to Food Webs The chapter introduces the concept of food webs and highlights the interconnectedness of organisms within these webs. It explains how the removal of a single species, such as grasshoppers, can have a domino effect on other organisms in the chain due to a lack of food resources. Additionally, the chapter emphasizes the importance of apex predators, like snakes, by illustrating how their removal can lead to an overpopulation of other species, such as frogs, thereby disrupting the balance and leading to resource scarcity for other species reliant on those prey.
• 06:30 - 07:30: Biodiversity and its Importance The chapter "Biodiversity and its Importance" discusses the complexity of ecosystems, emphasizing that they are not limited to simple food chains but consist of intricate food webs. The example given illustrates that a snake does not only eat frogs but may also consume rabbits and birds. This signifies that multiple food chains interact to form a food web, which illustrates the numerous interactions among various producers and consumers, highlighting the interconnectedness and richness of biodiversity.
• 07:30 - 08:30: The Role of Decomposers The chapter discusses the concept of biodiversity, which refers to the variety of organisms living in a given area. Factors such as the size and climate of the area influence biodiversity. Biodiversity is important for the sustainability of ecosystems, as it can help maintain balance if there is a reduction in certain species, like small birds.

Food Webs and Energy Pyramids: Bedrocks of Biodiversity Transcription

• 00:00 - 00:30 Captions are on! TO turn off, click the CC button at bottom right. Follow the amoebas on Twitter (@amoebasisters) and Facebook! When we were little, we loved nature shows. One reason was because we didn’t have cable and it was one of the few things we actually got a TV signal for that didn’t require you to dance around with the TV antennae for reception. But the other reason was that, of course, it was cool science. It often showed animals that we couldn’t see in our own backyard doing some AWESOME things. But then it would be traumatizing when, inevitably,
• 00:30 - 01:00 some predator would walk in and gobble the unsuspecting animal up. Truly, action scenes with predators and prey are often shown in nature shows because it’s all part of nature’s food chains. A food chain---starts with a producer. A producer is an organism that is an autotroph, which means it can make its own food. A plant for example. The plant is eaten by a primary consumer, this grasshopper. Consumers are heterotrophs,
• 01:00 - 01:30 which means they must feed on other organisms. The primary consumer is eaten by a secondary consumer, this frog. The secondary consumer is eaten by a tertiary consumer, this snake. And the food chain can keep going! Notice how the arrows are supposed to point in the direction of the one doing the eating---which makes sense---because that’s the direction of the energy flow. You can also arrange this same food chain into an energy pyramid. The producers at the
• 01:30 - 02:00 base here---in trophic level 1---- actually contain the most energy. What is crazy to think about is that the primary consumers here---in tropic level 2---actually only store 10% of the energy from the producers. Meaning, let’s say the plants here had 10,000 kilocalories (that’s an energy unit) of energy. Well the next level here---the primary consumers
• 02:00 - 02:30 in trophic level 2, would only store 1,000 kilocalories of energy. Where did the rest go? Much of it is lost in heat or undigested. If you go up to the secondary consumers in trophic level 3, that would be only 100 kilocalories of energy! It’s roughly only 10% of energy stored each trophic level up.
• 02:30 - 03:00 Back to our food chain. Notice that, like a domino effect, if something is removed ---let’s say the grasshoppers---you can harm the others because they may not have enough to eat. You really have to consider the relationships among organisms in a food chain. In fact, even if you took out the apex predator in this particular food chain---the snake---you could end up with an excessive population of frogs, so it’s possible the frogs would suffer from not having enough grasshoppers to support them.
• 03:00 - 03:30 You know, this is actually not a very good model, because in real life, this snake probably doesn’t just eat frogs. It probably eats rabbits and birds too. Because an ecosystem doesn’t typically have a single food chain, but instead, it has a food web. A food web is made up of multiple food chains that interact together. So notice now that we have multiple food chains here tied in with our original to make a food web The beauty of a food web is that it shows more interactions among a variety of producers
• 03:30 - 04:00 and various level consumers. It also can show biodiversity. Biodiversity is the variety of organisms---all types of organisms---living in a given area. The size of the area we are talking about as well as the climate of the area directly affect the biodiversity that is present. Biodiversity can contribute to the sustainability of an ecosystem. What I mean by that is---let’s say there was a decrease in the amount of small birds in this
• 04:00 - 04:30 food web---it is likely it could be harmful to other organisms. However, it is NOT the only thing that the snakes feed on. They have other options because of the biodiversity. They also eat rabbits and frogs. Because of the biodiversity, the ecosystem may be more resilient to changes such as these and possibly recover. However, these changes can still have detrimental effects, and this is why it is critical to protect ecosystem biodiversity.
• 04:30 - 05:00 High biodiversity has a lot of other benefits---that can include economics---and we’ll need another video to really touch on all the benefits of high biodiversity. So if we were to ask you which of our examples here had more biodiversity---our food chain or our food web---you would definitely want to pick the food web. One last thing! There are some organisms that we left out of our food webs and food chains,
• 05:00 - 05:30 but they are essential. Decomposers! Decomposers are heterotrophs since they do eat other things…even if the things they're eating are dead. Decomposers include organisms like bacteria and fungus. Technically if we were to draw them in…then every arrow would eventually point to them. Well that’s it for the amoeba sisters and we remind you to stay curious! Follow the amoebas on Twitter (@amoebasisters) and Facebook!