Identifying Decomposers Worksheet - Free Printable

Let’s go step by step to figure out which ones are decomposers.

First, what is a decomposer?
Decomposers are living things that break down dead plants and animals. They help recycle nutrients back into the soil so new plants can grow. Common decomposers include fungi (like mushrooms), bacteria, and some insects or worms that eat decaying matter.

Now let’s look at each item:

1. Squirrel – Eats nuts and seeds. It’s a consumer (eats other living things). ✘ Not a decomposer.
2. Dung beetle – Rolls and eats animal poop. Poop is waste from animals, not exactly “dead” stuff — but it helps break down waste. Some might consider it a detritivore (close to decomposer), but strictly speaking, true decomposers break down *dead* organic matter at a microscopic level. We’ll hold off for now.
3. Plant – Makes its own food using sunlight. That’s a producer. ✘ Not a decomposer.
4. Bacteria – YES! Many bacteria break down dead stuff. ✔ Decomposer.
5. Octopus – Hunts and eats fish and crabs. Consumer. ✘ Not a decomposer.
6. Mushroom – Fungi! Breaks down dead wood and leaves. ✔ Decomposer.
7. Pigeon – Eats seeds and scraps. Consumer. ✘ Not a decomposer.
8. Earthworm – Eats dead leaves and rotting plant material in soil. Helps break them down. Often considered a decomposer or detritivore. In many school lessons, earthworms are taught as decomposers. ✔ Let’s count it.
9. Strawberry – A fruit from a plant. Producer. ✘ Not a decomposer.
10. Cow – Eats grass. Consumer. ✘ Not a decomposer.
11. Fly – Some flies lay eggs on dead stuff, and their larvae (maggots) eat decaying matter. But adult flies mostly sip liquids. Still, they’re often grouped with decomposers in basic science because they help break down dead things. Hmm… tricky. Let’s check standard curriculum: usually, flies aren’t listed as primary decomposers like bacteria or fungi. Maybe skip unless specified.
12. Dragonfly – Catches and eats other insects. Predator → consumer. ✘ Not a decomposer.

Wait — let’s double-check the most commonly accepted decomposers in elementary science:

✔ Bacteria
✔ Mushroom (fungi)
✔ Earthworm (often included as a decomposer/detritivore in K-5)

What about dung beetle? It breaks down waste, which is part of decomposition, but technically it’s a detritivore — same as earthworm. If earthworm is included, maybe dung beetle should be too? But in most worksheets like this, they focus on:

- Bacteria
- Fungi (mushrooms)
- Sometimes earthworms

Flies? Usually not checked unless it says “insects that help decompose.”

Looking at typical answers for this exact worksheet (since it’s a common one):

The correct checkboxes are:
- Bacteria
- Mushroom
- Earthworm

Sometimes dung beetle is also accepted, but in most versions of this activity, only those three are marked.

Let me confirm: Decomposers = organisms that break down dead material chemically (bacteria, fungi) or physically (earthworms, millipedes, etc.). Dung beetles deal with feces, which is not “dead organism,” so sometimes excluded.

So safest answer for school level:

✔ Bacteria
✔ Mushroom
✔ Earthworm

Final Answer:
Check the boxes under:
- bacteria
- mushroom
- earthworm