Problem 3 - Campbell Biology Concepts & Connections

Question

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.

Step-by-Step Solution

Answer

d. eat their way through the soil, feeding on partially decayed organic matter.

Step 1: Understand the options

Read through each option carefully to understand the different feeding mechanisms described.

Step 2: Define substrate feeders

A substrate feeder is an organism that lives in or on its food source, eating its way through it. This helps in narrowing down the correct option.

Step 3: Eliminate incorrect options

Analyze each option: - Option (a) 'feed mostly on mineral substrates' is incorrect because earthworms feed on organic matter, not minerals. - Option (b) 'filter small organisms from the soil' is incorrect because earthworms do not filter-feed. - Option (c) 'are bulk feeders that ingest large pieces of food' is incorrect because earthworms consume food by breaking down organic matter in the soil.

Step 4: Verify the correct option

Option (d) 'eat their way through the soil, feeding on partially decayed organic matter' aligns with the definition of substrate feeders and describes earthworms' feeding technique accurately.

Key Concepts

substrate feeders

Earthworms are fascinating creatures known as substrate feeders. This term means that they live within and consume the material they call their habitat. Specifically, they eat their way through the soil. While doing so, they consume partially decayed organic matter found within it. Think of them as nature's tiny recyclers who transform dead leaves and plant material into nutrient-rich soil.

Unlike other feeders, earthworms do not hunt for food items or filter small organisms from their environment. Instead, they produce a combination of digestive enzymes and microorganisms in their gut to break down organic matter. This process helps them digest the soil they consume.

In summary, as substrate feeders, earthworms help to recycle nutrients back into the ecosystem by consuming and processing organic matter.

organic matter decomposition

Organic matter decomposition is a key process in nature, and earthworms play a vital role in it. When plants and animals die, their remains need to be broken down so their nutrients can be reused. Earthworms contribute to this process by consuming and digesting organic materials present in the soil.

As earthworms eat their way through decayed leaves, dead roots, and other organic materials, they turn them into simpler compounds. The partially digested material, also known as worm castings, is rich in nutrients. This makes it easier for plants to absorb these nutrients and grow.

By breaking down organic matter, earthworms help to ensure that these valuable nutrients do not go to waste. Instead, they cycle back into the soil, promoting plant health and agricultural productivity.

soil ecosystem

The soil ecosystem is a complex and dynamic environment, teeming with life and activity. Earthworms are crucial members of this ecosystem, contributing significantly to its health and sustainability.

Earthworms improve soil structure by creating tunnels as they move through the soil. These tunnels increase soil aeration, allowing roots to breathe and water to infiltrate more effectively. This reduces soil compaction and enhances plant growth.

Moreover, earthworm castings, which are the waste products they excrete, add essential nutrients and improve soil fertility. These castings are rich in nitrogen, phosphorus, and potassium, among other minerals, making them valuable for plant nutrition.

• Improved soil aeration
• Enhanced water infiltration
• Increased nutrient availability

Overall, earthworms play an indispensable role in maintaining the balance of the soil ecosystem, supporting plant growth, and fostering a healthy environment for various soil organisms.