3. Interdependence
3. Interdependence
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Describe the relationship between living and non-living things in the environment.
Define the food chain, food web, and explain how energy flows through an ecosystem.
Hey nature pals! Ever thought about how all the critters and plants in an ecosystem work together like a super cool team? That's what we call interdependence! It's like everyone, big or small, has a job that helps the whole gang. From the teeniest bugs to the tall trees, they're all part of this awesome web where what one does affects everyone else. Get ready to dive into a trip into the team-based world of ecosystems, where every little action matters!
Interdependence means the relationship between the living and non-living things in a given ecosystem. The non-living components of the ecosystem, such as water, air, and soil are required by living organisms to complete their life cycles. Living things are integral to the natural cycling process of water, air, and soil1. For example, plants take in carbon dioxide and return oxygen to the air through photosynthesis. Worms and other bacteria decompose dead animals and return rich minerals to the soil. Thus it can be said that both living and nonliving things are interdependent.
In an interdependent system, various species interact and rely on one another for essential resources such as food, shelter, or even processes like pollination. Changes or disruptions to one part of the system can have cascading effects on others, highlighting the delicate balance that exists in ecosystems2.
Example3:
i. The marigold plant relies on
1. Soil to anchor its roots;
2. Sun, rain, and air to produce its food;
3. Pollinating insects (e.g., butterflies, bees) to generate seeds for reproduction
Fig.3.1 Interdependence
ii. In return, the butterfly depends on the marigold for
1. Nectar for food & water
2. The caterpillar using leaves for food, water & shelter
3. Both use oxygen produced by plants to convert their food into energy
Fig. 3.2 Caterpillar on Marigold
Watch this video4 to learn more about Interdependence:
Vid. 3.1 Interdependence
Ecosystems are always changing, and it's because living things (organisms) and non-living things are interdependent. Organisms need non-living things like air, sunlight, water, and shelter, as well as living things like food. How these organisms get sunlight, water, shelter, and food shapes their environment.
Let's take an example: A group of animals walks through a forest to get to a water source. Their weight makes grooves in the ground, and when it rains, these grooves collect water, making them deeper. These deep grooves create a channel for water flow, which collects in an area that used to be dry. This change prompts plants to grow, attracting animals for food. This interconnected relationship alters the landscape and the behaviour of dependent organisms5.
a. Light:
The Sun's light is like a powerhouse for plants, helping them create both food and oxygen through photosynthesis. Additionally, sunlight gives us the warmth we need for life on Earth. Imagine if we didn't have the Sun's heat – Earth would turn into an icy place where most living things wouldn't survive6.
b. Water:
Every living creature requires water – it's a must-have. Water is important due to its ability to easily dissolve other substances. This enables water to transport nutrients in the living organisms and carry away waste. Without water, animals become weak and may even die. Just like when you feel thirsty after a run - Your body is telling you it needs water7.
c. Air:
Plants and animals help each other out by producing gases they each need. Plants need carbon dioxide, which is what people and animals breathe out. On the other hand, people and animals need oxygen, and that's what plants make during photosynthesis, a cool process of turning sunlight into food.
Fig. 3.3 Circulation of Oxygen and Carbon Dioxide
Ever notice clouds in the sky? That's water vapour. This water goes up into the air through the water cycle, and it also brings some molecules down into oceans, lakes, and rivers. It's like a big recycling system for air and water8!
Fig. 3.4 Air carries water Vapour
d. Soil:
It's mostly a mix of tiny rock bits (like sand and clay) along with decomposed plants and animals. Plants use their roots to absorb water and nutrients from the soil. Now, here's the cool part – soils change from one place to another, and this can affect the kinds of plants and animals that grow and thrive there7.
For example:
In a desert, the soil is sandy, lacking moisture and nutrients. This type of soil can only sustain plants that have adapted to survive with minimal rainfall.
Fig. 3.5 Desert
Conversely, in a rainforest, the soil may be low in nutrients but abundant in moisture. This environment supports towering trees, lengthy vines, and a variety of plants. These plants quickly absorb nutrients from the soil and often grow rapidly.
Fig. 3.6 Rainforest
All animals need energy to survive. They get this energy by eating other living things- plants or animals- in their environment. We can describe this interdependence of living things on other living things for energy through food chains and food webs.
A food chain shows who eats whom, while a food web includes all the food chains in an ecosystem. Every living thing in an ecosystem has its place, called a trophic level, in the food chain or web9.
Fig. 3.7 Food Chain
a. Food Chain:
a. Food Chain:
Each food chain is like a pathway that energy and nutrients can take through the ecosystem.
Take, for instance, a simple food chain: grass makes its food from sunlight, a rabbit eats the grass, a fox eats the rabbit, and when the fox dies, bacteria break it down, giving nutrients back to the soil for plants like grass.
Fig. 3.8 Food Chain
But here's something interesting: lots of different animals eat grass, and rabbits can munch on plants other than grass. Foxes, on the other hand, can feast on many kinds of animals and plants. Each of these living things can be part of multiple food chains. All these connected and tangled food chains in an ecosystem form what we call a food web9.
In food chains, organisms are categorised into trophic levels as follows:
Lets learn the above points in detail
Producers, or autotrophs (where ‘auto’ means self and ‘troph’ means nourishment), are organisms that produce their own food, forming the first level of every food chain. Generally, autotrophs are plants or some other organisms. Almost all autotrophs a process called photosynthesis to produce their own "food" (a nutrient known as glucose) from sunlight, carbon dioxide, and water9.
The food they produce provides them the energy to grow and reproduce5.
Fig. 3.9 Producer (Grass)
All other organisms depend on the producers for food in a food chain.
The second trophic level is made up of organisms known as primary consumers or herbivores. Primary consumers consume producers and derive the energy they need to perform different life functions. Typically smaller in size, there's a large population of these creatures5.
Fig. 3.10 Primary Consumer (Grasshopper)
Secondary consumers form the third trophic level and they depend on primary consumers for food. They can be carnivores or omnivores10.
Carnivores are animals that primarily feed on other animals. These animals play a crucial role in maintaining the balance of ecosystems by controlling the population of herbivores and other prey species11.
Omnivores are animals that eat both plants and animals. They have a diverse diet that includes a combination of fruits, vegetables, meat, and other food sources. Humans, bears, and pigs are examples of omnivores.
Fig. 3.11 Secondary Consumer (Frog)
Fig. 3.12 More examples of secondary consumer (Lion, Eagle and Shark)
There might be additional consumer levels before reaching the top predator, also known as the apex predator. Apex predators prey on other consumers.
Fig. 3.13 Trophic Levels in a Food Chain
Watch this video12 to recap our learning:
Vid. 3.2 Food Chain
b. Food Web:
b. Food Web:
In nature, there are many interconnected food chains that create something called a food web. In an ecosystem, one creature can be the food for several others while also hunting others itself. This interconnection creates a complex food web with many levels. The image below shows an example of a food web14.
Vid. 3.14 Grassland Food Web
In a grassland, the grass is the main producer, starting the food chain. A grasshopper, a primary consumer, eats the grass. Then, a frog, a secondary consumer, eats the grasshopper. Moving up, a snake, a tertiary consumer, preys on the frog. Finally, a hawk, the top consumer, eats the snake. When the hawk dies, decomposers release nutrients into the soil for the grass to use.
In another part of the food chain, a caterpillar, a primary consumer, eats plant leaves (producers), which are then consumed by sparrows, secondary consumers. A snake, a tertiary consumer, eats the sparrow, and an eagle, the apex consumer, preys on the snake. To complete this chain, a vulture feeds on the eagle, and decomposers break down the eagle after its death.
These food chains overlap in the ecosystem with many others, where one organism has more than one prey. Similarly, the same organism can have multiple predators, forming a connected network of relationships across different levels of the ecosystem – the food web.
Glossary
photosynthesis: the process by which plants use sunlight to make their food.
decompose: to break down dead plants and animals into nutrients for the soil.
pollination: the process of moving pollen from one flower to another to help plants make seeds.
organism: any living thing, such as a plant, animal, or tiny bacteria.
trophic level: the position an organism has in the food chain.
apex predator: a predator at the top of the food chain that is not eaten by other animals.
Summary
Interdependence refers to the relationship between living and nonliving elements within an ecosystem.
Nonliving components like water, air, and soil are essential for the life cycles of living organisms.
Living things play a crucial role in the natural cycling of water, air, and soil, contributing to processes like photosynthesis and decomposition.
Examples include plants taking in carbon dioxide and releasing oxygen, and worms decomposing dead animals to enrich the soil.
Animals obtain energy by consuming other living things, either plants or animals, in their environment.
A Food chain describes how energy and nutrients move through an ecosystem.
Producers (autotrophs) create food for themselves and other organisms using sunlight.
Consumers rely on other organisms for food, with categories like herbivores (eat plants), carnivores (eat animals), and omnivores (eat both).
The food web encompasses all the food chains within a single ecosystem.
Food web demonstrates the complex interconnections between different species and their roles in the flow of energy.
References
1 Communities. BBC Bitesize, n.d, link
2 How to Describe the Interdependence of Living Organisms ? Sciencing, n.d, link
3 Interdependent in Nature. Maggie’s Science Connection, n.d, link
4 Interdependence Between Living and non living Things. YouTube, n.d, link
5 Interdependent Relationships in Ecosystems. Learning Centre, n.d, link
6 Ecosystems. Lake Forest Lakers, n.d, link
7 Important Abiotic Factors. Cusd80, n.d, link
8 Air. National Geographic, n.d, link
9 Food Chains and Webs. National Geographic, n.d, link
10 Food Web. Science Facts, n.d, link
11 Carnivore. National Geographic, n.d, link
12 What is a Food Chain. Youtube, n.d, link
13 Food Chain: Definition, Levels, Examples. Embibe, 2023, link
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