Which term best describes organisms that break down wastes and dead organisms?

• A. Autotroph
• B. Decomposer
• C. Detritovore
• D. Heterotroph

Answer: (B)

Decomposition and nutrient recycling in ecosystems are driven by decomposers. These organisms break down wastes and dead organisms into simpler inorganic nutrients that other organisms can reuse. Most decomposers are fungi and bacteria, and they typically do extracellular digestion—secreting enzymes onto the material and then absorbing the resulting nutrients.

Detritivores, such as earthworms, do break down detritus by ingesting it and digesting it internally, but the term decomposer specifically describes the organisms that chemically break down organic matter into nutrients available to the rest of the ecosystem. Autotrophs produce organic matter, and heterotrophs obtain energy by consuming others; decomposers are a specialized group within heterotrophs focused on decomposition.