Question

What does a Detritus food chain begin with?

• A. Living green plants
• B. Herbivores
• C. Dead organic matter
• D. Top consumers

Answer 1

Answer:

C. Dead organic matter

Detritus Food Chain (DFC) Explained

• A Detritus Food Chain (DFC) fundamentally begins with dead organic matter, which includes dead plants, animals, and their waste products. This is in stark contrast to a Grazing Food Chain (GFC), which starts with living green plants (producers).
• The primary consumers in a DFC are organisms known as detritivores (also called decomposers or saprotrophs). These include bacteria, fungi, earthworms, mites, millipedes, slugs, and certain insects like springtails.
• Detritivores feed on the dead organic matter, breaking it down into simpler inorganic substances through processes like decomposition and mineralization.
• Energy transfer in a DFC flows from dead organic matter to detritivores, then to their predators, and so on. For instance, detritus is consumed by earthworms, which are then eaten by birds.
• This food chain plays a crucial role in nutrient cycling within an ecosystem. Decomposers release inorganic nutrients (like nitrogen, phosphorus, and potassium) back into the soil, water, and air, making them available for producers (plants) to reuse.
• In many terrestrial and aquatic ecosystems, the detritus food chain accounts for a significantly larger proportion of energy flow than the grazing food chain. For example, in a forest ecosystem, a large amount of plant biomass falls as dead leaves and branches, fueling the DFC.
• The DFC is vital for recycling matter and maintaining ecosystem stability. Without it, dead organic matter would accumulate, and essential nutrients would not be returned to the ecosystem for new growth.
• Both the grazing and detritus food chains are interconnected in nature. For example, organisms from the DFC can become food for organisms in the GFC (e.g., a bird that eats an earthworm).
• Key organisms in DFC for competitive exams:
  • Primary producers: Dead organic matter.
  • Primary consumers (detritivores): Bacteria, Fungi, Earthworms, Millipedes, etc.
  • Secondary consumers: Predators of detritivores.