Decomposers and food chains
Organic matter is recycled in an ecosystem by decomposers. Decomposers are organisms such as bacteria and fungi that break down the organic matter in the dead bodies of plants and animals. As the decomposers feed from the dead animals, they break down the organic compounds into simple nutrients. These simple nutrients are returned to the soil and can be used again by the plants. The energy transformation chain begins again.
Decomposers are nature's recyclers as they break down the organic matter found in the dead bodies of plants and animals. The term 'organic matter' refers to the matter that comes from living organisms. Decomposers are chiefly the micro-organisms such as bacteria and fungi in the form or yeasts and moulds that break down bodies of dead organisms and release compounds that can be used by producers. Some of these compounds include nitrogen, phosphorus and magnesium. There are more than 100 000 different types of decomposer organisms.
Bacteria and fungi produce chemicals, called enzymes that digest dead material. The digested material then provides a food source for other organisms in the soil. This makes the role of a decomposer extremely important in an ecosystem. Without them, organic matter would pile up on the ground and plants would not receive the required nutrients necessary for their survival. The decomposing process greatly increases the nutrient-load of an ecosystem which allows for greater biodiversity.
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Biodiversity refers to the number of different species in a community. High biodiversity is when many different species of plants and animals live together. Low biodiversity refers to communities with a small number of different species. A community with high biodiversity is more able to survive changes in the environment as there are alternative food sources. If one species of plant dies out in a community with high biodiversity, there still should be another plant species that the herbivores and omnivores can eat in its place.
Scavengers are also important in an ecosystem. A scavenger is an animal, bird or insect that feeds on dead or decaying matter. They are useful to the ecosystem as they feed on and break down the remains of dead animals and plants. Any remains left behind by the scavengers are then broken down even further by decomposers.
Scavengers include vultures, blowflies, wedge-tailed eagles and foxes. Many large carnivores that hunt regularly such as hyenas and lions will also scavenge if necessary and given the chance.
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Other organisms that perform similar roles to decomposers and scavengers are the detrivores. A detrivore is a plant or animal that feeds on the organic remains or other organic debris from other organisms. They recycle detritus, which is decomposing organic material and return it to the food chain.
Earthworms, millipedes, woodlice and dung beetles are examples of detritus feeders. Earthworms eat the rotting plant leaves and other debris and help to aerate and mix the soil. Other detritus feeders such as dung beetles eat faeces, which often contain considerable nutrients. Some of the detritus that is consumed by the detrivores may already have been partially or fully decomposed by decomposers.
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