The Major Biotic / Living Components Of Ecosystems  

The Major Biotic / Living Components Of Ecosystems

1. Producer:

  • are autotrophs capable of synthesizing complex organic food materials from simple inorganic food raw materials e.g carbon dioxide and water.
  • Examples include; large green terrestrial plants e.g trees, shrubs, grass. For aquatic ecosystem, the producers are microscopic algae, blue green bacteria. Others are flagellates like euglena, volvox, chlamydomonas etc. They are collectively called Phytoplanktons (microscopic marine producers)

NB; Some producers use chemical energy derived from breakdown of chemical compounds like sulphur to convert carbon dioxide  and water into high energy compounds like carbohydrates e.g sulphur bacteria i.e they are chemosynthetic.

2. Consumer: 

Are organisms that get energy and nutrients by feeding on other organisms or their remains . Ø Are classified as;

(i)  Primary consumers(Herbivore): 
  • A consumer that eats plants.
  • E.g. insects, birds, most mammals(grazers), 
  • In aquatic ecosystem, they include; water fleas, fish, crabs, mollusks, and protozoans, collectively known as zooplanktons(microscopic marine consumers).

(ii) Secondary consumers(Carnivore):  ü A consumer that eats other animals.

  • E.g. birds of prey like eagle, kites, kingfishers; and lions, cheetahs, tigers, hyenas, snakes, big fish,  (iii) Tertiary consumers:
  • These feed on both primary and secondary consumers 
  • Can be predators that hunt and kill others for food or scavengers(animals that feed on dead organisms but do not kill them.
  • E.g. vultures, hyenas, marabou stocks etc

(iv) Omnivore: A consumer that eats both plants and animals .e.g. man, pigs,etc 

3. Decomposer: 

  • An organism that feeds on dead organic matter.
  • Classified into; 
(i) Detrivore/ macro decomposers; 
  • An animal that eats detritus.(dead and waste matter not eaten by consumers)
  • E.g earth worms, rag worms, mites, maggots, wood lice, termites etc.   
(ii) Saprophyte: 

A microbe (bacterium or fungus) that lives on detritus. 

Importance of decomposition:

  • It enables dead bodies to be disposed off which, if left would accumulate everywhere. 
  • Recycles nutrients to be used by other organisms e.g. Mineral salts are released from dead bodies into soil for plant growth.
  • Unlocks trapped energy in the body of dead organisms.

Energy flow through an ecosystem  

  • The sun is the primary source of energy in the ecosystem. 
  • Light energy is trapped by photosynthetic organisms (green plants, algae, and some bacteria); converted into chemical energy by during photosynthesis.
  • It is then transferred from one feeding level to another through feeding relationships like food chains or food webs.
  • Most of the energy from sun getting the earth’s surface is reflected by vegetation, soil, and water or absorbed and radiated to atmosphere; leaving only between 5%-10% for the producers to make use of.
  • Along the food chain, only a small proportion of the available energy is transferred from one feeding level to another; much energy is lost as heat during sweating and evaporation, excretion , respiration, egestion, and some remains locked up in indigestible parts of the plant like cellulose, or bones, hooves, hair, skin etc of animals.  
  • The number of organisms decrease at each successive feeding level because of the great energy losses, so the energy left in organisms is little to support large numbers of top consumers; limiting the length of food chain( not exceeding five trophic levels( feeding level in a food chain containing given amount of energy).       

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