Which of the following are detritivores?
- 1.Earthworms
- 2.Jellyfish
- 3.Millipedes
- 4.Seahorses
- 5.Woodlice
Select the correct answer using the code given below.
Answer & explanation
Answer: (c) 1, 3 and 5 only
Detritivores eat detritus, the dead leaves, wood, dead animals and dung on and in the soil, and break it into small fragments, which starts decomposition. Earthworms, millipedes and woodlice all live in leaf litter and feed this way. Jellyfish and seahorses are marine predators that catch live prey.
- ✓ 1. Earthworms are the textbook detritivore: they fragment dead plant matter, the first step of decomposition.
- ✗ 2. Jellyfish are cnidarians that sting and capture live prey with their tentacles.
- ✓ 3. Millipedes feed directly on detritus (dead plant matter) and so speed up decomposition, as a US Forest Service study notes; they are detritivores.
- ✗ 4. Seahorses are ambush predators that suck small live crustaceans such as shrimps and amphipods into their snouts.
- ✓ 5. Woodlice are land crustaceans (isopods) that feed mainly on decomposing plant material, helping recycle nutrients.
Remember · Detritivores fragment dead organic matter: earthworms, millipedes, woodlice, termites, dung beetles, sea cucumbers. Decomposers (bacteria, fungi) then break it down chemically.
📘 Read it in NCERT: Class 12 Biology, Ch 12 (practise this chapter) · Class 9 Exploration, Ch 12 (practise this chapter)
Sources
- NCERT Class 12 · Biology, Chapter 12 “Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called fragmentation.”
- NCERT Class 9 · Exploration, Chapter 12 “Unlike poriferans, cnidarians can catch their prey using tentacles instead of depending on water currents to bring food particles inside through pores.”
- USDA Forest Service, International Institute of Tropical Forestry: Direct and indirect effects of millipedes on the decay of litter ↗ “Millipedes are considered to be important organisms involved in decomposition, both for their direct feeding on detritus and their indirect effects on microbial activity.”
- Royal Horticultural Society, Woodlice ↗ · reference work “Function - Detritivores, mainly feeding on decomposing plant materials”
- Florida Museum of Natural History, Longsnout Seahorse ↗ · reference work “The diet of the longsnout seahorse consists of ghost shrimp, grass shrimp, opossum shrimp, amphipods, and other small marine crustaceans.”
Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·