Earthworms, which are substrate feeders,
a. Feed mostly on mineral substrates.
b. Filter small organisms from the soil.
c. Are bulk feeders that ingest large pieces of food.
d. Eat their way through the soil, feeding on partially decayed organic matter.

Verified step by step guidance

Step 1: Understand the term 'substrate feeders'—these are organisms that consume organic material found within or on a substrate, such as soil or decaying matter.

Step 2: Recognize that earthworms are known for their ecological role in soil ecosystems, where they consume organic matter and contribute to nutrient cycling.

Step 3: Clarify that earthworms ingest soil as they move through it, extracting nutrients from partially decayed organic matter within the soil.

Step 4: Eliminate incorrect options by analyzing the feeding behavior of earthworms. For example, they do not feed on mineral substrates exclusively, nor do they filter small organisms from the soil.

Step 5: Conclude that earthworms eat their way through the soil, feeding on partially decayed organic matter, which aligns with their role as substrate feeders.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Substrate Feeding

Substrate feeding refers to the feeding strategy where organisms consume material from their environment, typically by ingesting the substrate they inhabit. In the case of earthworms, they feed on the organic matter and microorganisms present in the soil, which helps in nutrient cycling and soil aeration.

Bulk Feeding

Bulk feeding is a type of feeding mechanism where organisms consume large quantities of food at once, rather than filtering or selectively feeding on smaller particles. Earthworms exemplify this by ingesting significant amounts of soil, which contains decaying organic matter, allowing them to extract nutrients efficiently.

Decomposition and Nutrient Cycling

Decomposition is the process by which organic matter is broken down into simpler substances, releasing nutrients back into the ecosystem. Earthworms play a crucial role in this process by consuming partially decayed organic matter, aiding in its breakdown, and enhancing soil fertility through their waste, which is rich in nutrients.

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