Abiotic and biotic parts of an ecosystem

An ecosystem is made up of the interaction of all organisms in an area with all nonliving things. Organisms are living things like animals, plants, and microbes. Nonliving things include water, dirt, rocks and the sun. The living things are called biotic components and the nonliving things are called abiotic components.

There are a few different types of biotic components. Producers are living things that use a process called photosynthesis, which turns the sun's energy, water and carbon dioxide into fuel. Producers form the molecules that are the basis for all life on Earth, including plants, algae and some bacteria.

Consumers are animals that get their energy from eating other plants and animals. Decomposers are organisms that break down animal and plant material to make nutrients available. Examples of decomposers are bacteria, fungi and insects.

Abiotic components include temperature, sunlight, water, wind and minerals.

The food chain: who eats who in the wild

The food chain describes who eats whom in the wild. Every living thing — from one-celled algae to giant blue whales — needs food to survive. Each food chain is a possible pathway that energy and nutrients can follow through the ecosystem.

For example, grass produces its own food from sunlight. A rabbit eats the grass, then a fox eats the rabbit. When the fox dies, bacteria break down its body, returning it to the soil where it provides nutrients for plants, like grass.

Of course, many different animals eat grass, and rabbits can eat other plants besides grass. Foxes, in turn, can eat many types of animals and plants. Each of these living things can be a part of multiple food chains. All of the interconnected and overlapping food chains in an ecosystem make up a food web.

Trophic Levels

Organisms in food chains are grouped into categories called trophic levels. Roughly speaking, these levels are divided into producers (first trophic level), consumers (second, third and fourth trophic levels) and decomposers.

Producers, also known as autotrophs, make their own food. They make up the first level of every food chain. Autotrophs are usually plants or one-celled organisms. Nearly all autotrophs use a process called photosynthesis to create "food" (a nutrient called glucose) from sunlight, carbon dioxide and water.

Plants are the most familiar type of autotroph, but there are many other kinds. Algae, whose larger forms are known as seaweed, are autotrophic. Phytoplankton, tiny organisms that live in the ocean, are also autotrophs. Some types of bacteria are autotrophs. For example, bacteria living in active volcanoes use sulfur compounds to produce their own food. This process is called chemosynthesis.

The second trophic level consists of organisms that eat the producers. These are called primary consumers, or herbivores. Deer, turtles and many types of birds are herbivores. Secondary consumers eat the herbivores. Tertiary consumers eat the secondary consumers. There may be more levels of consumers before a chain finally reaches its top predator. Top predators, also called apex predators, eat other consumers.

Consumers can be carnivores (animals that eat other animals) or omnivores (animals that eat both plants and animals). Omnivores, like people, consume many types of foods. People eat plants, such as vegetables and fruits. We also eat animals and animal products, such as meat, milk and eggs. We eat fungi, such as mushrooms. We also eat algae, in edible seaweeds like nori (used to wrap sushi rolls) and sea lettuce (used in salads).

Detritivores and decomposers are the final part of food chains. Detritivores are organisms that eat nonliving plant and animal remains. For example, scavengers, such as vultures, eat dead animals. Dung beetles eat animal feces.

Decomposers like fungi and bacteria complete the food chain. They turn organic wastes, such as decaying plants, into inorganic materials, such as nutrient-rich soil. Decomposers complete the cycle of life, returning nutrients to the soil or oceans for use by autotrophs. This starts a whole new food chain.

Food Chains

Different habitats and ecosystems provide many possible food chains that make up a food web.

In one marine food chain, single-celled organisms called phytoplankton provide food for tiny shrimp called krill. Krill provide the main food source for the blue whale, an animal on the third trophic level.

In a grassland ecosystem, a grasshopper might eat grass, a producer. The grasshopper might get eaten by a rat, which in turn is consumed by a snake. Finally, a hawk — an apex predator — swoops down and snatches up the snake.

In a pond, the autotroph might be algae. A mosquito larva eats the algae, and then perhaps a dragonfly larva eats the young mosquito. The dragonfly larva becomes food for a fish, which provides a tasty meal for a raccoon

Carbon is one of the most important chemical elements found on Earth. It is stored in many different places, and these places are known as reservoirs.

For example, carbon is found as carbon dioxide in the atmosphere, which is the layer of gasses that surrounds a planet. It is found in the organic matter that makes up soil, and in living things like plants an animals. It is found in the oceans, fossil fuels and plant and animal life.

Carbon doesn't stay in one place, though. It transfers from one reservoir to another. The way carbon is used, converted and transferred through the world is called the carbon cycle.

For example, carbon enters the soil from decaying organisms like dead leaves or compost. The carbon in soil is consumed by plants, which are consumed by animals. Animals, and humans, release carbon dioxide gas into the atmosphere when they breathe out, or when they burn fossil fuels. Plants take up carbon dioxide from the air to use during photosynthesis, which is a process that converts sunlight and carbon dioxide gas into food.

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In an ecosystem, energy and nutrients are passed among living things. Different organisms play different roles. Some, such a plants, produce energy using a process called photosynthesis. Other organisms get their energy from eating these producers. This forms a complex web of organisms that produce and consume one another. If any species is removed from the ecosystem, the entire food web is affected.

Decomposers include fungi, bacteria and some insects. They feed on dead animals and plants. This process breaks down the dead organisms and returns nutrients to the soil. Primary producers are plants that make energy-packed food. Primary consumers, or herbivores, are organisms that eat only plants. Secondary consumers are organisms that eat primary consumers. Some secondary consumers eat only meat while others eat both meat and plants. Tertiary consumers eat primary and secondary consumers. Usually, they only eat meat, but some species eat plants too.