The following lessons that will be discussed would be the flows of energy, food chain, and trophic levels. At the end of this lesson, you should be able to understand the flow of energy and matter in ecosystem, create the flow of energy and matter in ecosystem, and appreciate the importance of the flow of energy and matter in ecosystem. From the past lessons, we understand that ecosystems require constant inputs of energy from sunlight or chemicals. As a review, the biotic components of an ecosystem includes Autotrophs can make their own food by combining sunlight, water, and carbon dioxide to make glucose and oxygen in the process of photosynthesis.
Photosynthesis, maybe the most important biochemical reaction of Earth, is the process by which green plants and certain other organisms transform light energy into chemical energy. While heterotrophs are organisms that cannot produce their own food and must feed on other organisms to get energy. As energy enters through an ecosystems in the form of sunlight or chemical compounds. Some organisms use this energy to make food.
Other organisms get energy by eating the food. Thus, energy moves in a single direction. Producers are organisms that produce food for themselves and other organisms.
Producers are also called autotrophs. There are two basic types of autotrophs, photoautotrophs and chemoautotrophs. Photoautotrophs use energy from sunlight to make food by photosynthesis.
They include plants, algae, and certain bacteria. Hence, Sunlight is the main energy source for all life on earth. But what about very deep in the ocean where the sunlight does not penetrate?
Some procedures in these areas are adapted to obtain their energy from inorganic compounds such as hydrogen sulfide to produce the carbon-containing sugar molecules necessary to maintain life. They are called chemoautotrophs which use energy from chemical compounds to make food by chemosynthesis. They include some bacteria and also archaea. Archaea are microorganisms that resemble bacteria. On the other hand, consumers are organisms that depend on other organisms for food.
They take in organic molecules by essentially, eating, other living thing. Consumers are also called heterotrophs. Heterotrophs are classified by what they eat.
Herbivores, are heterotrophs that obtain their matter and energy by feeding directly and only on producers. Carnivores are organisms that mostly eats meat, or the flesh of animals. Sometimes carnivores are called predators.
Omnivores. sometimes consume producers and other times may consume other heterotrophs. Detritivores, also known as detrivores or detritus feeders or detritus eaters, are heterotrophs that obtain nutrients by consuming detritus, which are decomposing plant and animal parts as well as feces, they also act as the cleaner of the earth. Types of detritivores First, is the scavengers, which are heterotrophs that eat animals that have already died, they helps clean up dead and decaying organisms.
Examples of scavengers include vultures, raccoons, and blowflies. Decomposers, on the other hand, break down the remains and other wastes and release simple inorganic molecules back to the environment. Producers can then use the molecules to make new organic compounds.
The stability of decomposers is essential to every ecosystem. Saprotrophs are the final step of decomposition, they feed on remaining organic matter that has left after other decomposers do their work. Saprotrophs include fungi and single no-celled protozoa. So what are the differences between scavengers and decomposers? Scavenger ingests the organic matter and then digest it, while decomposers secretes digestive enzymes onto the dead organic matter first, and then observe the digested material from that organic matter.
And now we will proceed to the main topic which is the transfer of energy and other pathways. Here are some of the terms that we will be tackling. As discussed earlier, Energy and matter begin to move throughout the ecosystem when a producer uses photosynthesis to create the sugar it needs to carry out life processes. The movement of energy and matter in an ecosystem is reflected in a food chain and food web.
Energy must constantly flow through an ecosystem for the system to remain stable. What exactly does this mean? Essentially, it means that organisms must eat other organisms. The food chain as presented in the picture show the eating patterns in an ecosystem. Food energy flows from one organism to another.
Arrows are used to show the feeding relationship between the animals. The arrow points from the organism being eaten to the organism that eats it. For example, an arrow from a plant to a grasshopper shows that the grasshopper eats the leaves.
Energy and nutrients are moving from the plant to the grasshopper. Next, a frog might prey on the grasshopper, a snake may eat the frog, and then an owl might eat the snake, making the owl the apex predator. These are the consumers at the highest level of the food chain that no longer have predators.
Each organism can eat and be eaten by many different types of organisms, so simple food chains are rare in nature. In ecosystems, there are many food chains. Since feeding relationships are so complicated, we can combine food chains together to create a more accurate flow of energy within an ecosystem.
A food web shows the feeding relationships between many organisms in an ecosystem. A food web shows many more arrows, but still shows the flow of energy. Thus, a complete food web may show hundreds of different feeding relationships.
The picture shows the overlapping food web across terrestrial and aquatic ecosystems. The transfer between ecosystems happened when an organism that lives in a terrestrial ecosystem consumes an organism in an aquatic or aquatic-to-terrestrial ecosystem, energy is transferred between the two. Example, a bear eats a fish, energy from aquatic-to-terrestrial, or fish eats a caterpillar, energy from terrestrial-to-aquatic. However, during the transfer of energy, some energy is lost.
When a lion eats a zebra, it does not get all of the energy from the zebra. Energy lost is usually in form of heat. Next topic would be the trophic levels.
The feeding positions in a food chain or web are called trophic levels. In the trophic level, producers occupy the bottom of the pyramid, while consumers occupy the higher trophic or feeding levels. The energy lost from one trophic level to the next level can be represented by a pyramid.
Generally, there are a maximum of four trophic levels. Energy is passed up a food chain or web from lower to higher trophic levels. However, generally only about 10% of the energy at one level is available to the next level.
This is represented by the ecological pyramids shown in the slide. Each level above only gets 10% of the energy from below. Example 10,000 joules of producers, plants, only give 10% of energy to primary consumers. 1,000 joules to primary consumers, snails, minnows, dragonflies, 100 joules to secondary consumers, small fish, 10 joules to tertiary consumers, big fish, 1 joules to quaternary consumers, fishhawk. As you move up through the trophic levels, the amount of available energy decreases.
So, what happens to the other 90% of energy? It is used for metabolic processes or given off to the environment as heat. This loss of energy explains why there are rarely more than 4 trophic levels in a food chain or web.
Sometimes there may be a 5th trophic level. but usually it does not have enough energy left to support any additional levels. Ecological pyramids can demonstrate the decrease in energy, biomass or numbers within an ecosystem.
With less energy at higher trophic levels, there are usually fewer organisms as well. Organisms tend to be larger in size at higher trophic levels, but their smaller numbers result in less biomass. Biomass is the total mass of organisms at a trophic level.
Thank you for listening.