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The nutrient chain
Plants, algae and some bacteria are called _______ because they can create their own food.
Cool moves Michael. Are you hungry? You have used a lot of energy dancing. How about a little snack to get the energy back? Every living thing needs energy to function.
And energy comes from food. Food contains different substances which change into energy inside our bodies. These are called nutrients. How does our food get nutrients - like this apple? Do plants also need to eat?
Plants, algae, and some bacteria can produce their own food. To do that, they use sunlight, carbon dioxide from the air, and water from their environment. They turn these into OXYGEN, and a nutrient called GLUCOSE - which is their food. This gives them energy to survive and grow. This chemical process is called PHOTOSYNTHESIS.
Because plants can produce their own food they are called PRODUCERS. And because they do it without using other living organisms they are also called self-sustaining or AUTOTROPHIC organisms. Plants don’t use all the energy at once, but they store some of it inside. Some organisms don’t produce their own food but they eat others instead. These are called HETEROTROPHIC organisms.
Some of these are herbivores - they eat plants. This means they are PRIMARY CONSUMERS. When for instance a zebra eats a plant, it absorbs nutrients from the plant. Then, these can be converted into energy. Now, the zebra can use this energy for itself... ...until another animal eats the zebra, for example a lion.
Lions eat meat. They are CARNIVORES and SECONDARY CONSUMERS. When the lion eats the zebra, the lion also receives nutrients to produce energy. When the lion dies, it too now becomes food, for example for vultures, which eat dead animals. Vultures are SCAVENGERS.
In this case, vultures are TERTIARY CONSUMERS. Their food also contains nutrients which turn into energy inside the vultures’ bodies. The nutrients flow in one direction - from the producer upwards - connecting the different consumers in a chain. That’s why it’s called the nutrient chain. But does this mean that the consumers on the highest level receive all the nutrients and energy that the plants originally produced? [...] No.
Organisms use most of the energy themselves for moving, breathing, or keeping warm. They can only store a small part of the energy they produce. At each level, about 90% of the energy is used, and only about 10% is available for the next consumer up the chain. The energy left for the top consumers in a food chain is a tiny portion of the energy that was in the producers. Hmm… But what happens when the vulture dies?
Tiny organisms, such as insects, worms, bacteria, and fungi, take care of it! They decompose the leftovers and organic waste into simpler substances like water, carbon dioxide, and nutrients. These organisms are called decomposers. Plants use these simple substances to produce energy, using photosynthesis. Decomposers can do their job at any level of the food chain, eating waste and dead organisms.
Using energy from the sun, plants produce nutrients. These move from one organism to another within a food chain. Thanks to the decomposers, the nutrients return to the environment. All elements in nature are connected, and the energy flows between them all the time. That’s good to know, because it seems like Michael is going to need a lot of energy tonight!