Food Chains Worksheet - Free Printable

Let’s solve this step by step.

We are given a word bank:
flower, owl, penguin, seaweed, sun

But note — “sun” is already used in every chain as the starting point (energy source), so we won’t use it again to fill blanks. We’ll pick from: flower, owl, penguin, seaweed

Now let’s look at each food chain and figure out what’s missing.

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Chain 1:
Sun → ___ → butterfly → bird → snake

What does a butterfly eat? Butterflies often drink nectar from flowers. So the blank should be flower.

✔ Chain 1: Sun → flower → butterfly → bird → snake

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Chain 2:
Sun → algae → krill → ___ → orca

Krill are tiny shrimp-like animals. What eats krill? Penguins! And then orcas eat penguins.

So the blank is penguin.

✔ Chain 2: Sun → algae → krill → penguin → orca

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Chain 3:
Sun → wheat → mouse → ___

Mice are eaten by owls. Owls are predators that hunt small animals like mice.

So the blank is owl.

✔ Chain 3: Sun → wheat → mouse → owl

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Chain 4:
___ → acorn → squirrel → coyote

Acorns come from oak trees, but “tree” isn’t in our word bank. Wait — what produces acorns? Actually, acorns are seeds of oak trees, but here we need something that comes before acorn in the chain. The sun gives energy to plants, but “sun” is already shown elsewhere. However, looking at the pattern — the first item in other chains after “sun” is a plant or producer.

Wait — actually, in this chain, there’s no “sun” shown at the start. The blank is the very first thing. But all food chains start with the sun giving energy to producers. However, since “sun” is not in the word bank for filling blanks (it’s already listed separately), and we have “seaweed” left… but seaweed doesn’t make acorns.

Hold on — maybe I made a mistake. Let’s recheck.

Actually, looking again: In chain 4, the blank is BEFORE acorn. Acorns come from oak trees — but “oak tree” isn’t an option. Our options are: flower, owl, penguin, seaweed.

None of those produce acorns. That can’t be right.

Wait — perhaps the blank is meant to be the producer that makes the acorn? But acorns are made by trees, which aren’t listed.

Alternatively — maybe the diagram has a mistake? Or perhaps I misread.

Looking back at the image description: The fourth chain starts with a blank, then acorn, then squirrel, then coyote.

In real life, acorns come from oak trees, which get energy from the sun. But since “sun” is not available to fill blanks (it’s already used as the starter in others), and we have “seaweed” left — but seaweed is aquatic and doesn’t relate to acorns.

This suggests maybe the intended answer is sun, even though it’s in the word bank? But the instruction says “fill in the missing organism”, and sun is not an organism — it’s an energy source.

Wait — let’s check the example in the box:
“Example: Sun → grass → rabbit → fox”

So sun is included as part of the chain, but it’s not an organism. The question says “missing organism”, so sun shouldn’t be used to fill blanks.

Then what goes before acorn? It must be a plant that produces acorns — but none of the remaining words fit.

Unless... perhaps the blank is supposed to be “sun”? But again, sun is not an organism.

Wait — let’s list what we’ve used:

Chain 1: flower
Chain 2: penguin
Chain 3: owl
Left: seaweed

Chain 5: Sun → ___ → fish → seal → shark

Fish eat what? Small fish or plankton. Seaweed is a producer — some fish eat seaweed directly, or eat things that eat seaweed.

In marine food chains, seaweed (or algae) is often the producer. Here, algae was used in chain 2, but seaweed is similar.

So for chain 5: Sun → seaweed → fish → seal → shark

That makes sense — some fish eat seaweed, seals eat fish, sharks eat seals.

So chain 5 blank = seaweed

Then chain 4 still needs a blank before acorn.

But we’ve used all words except... wait, we have five blanks and five words including sun? No, the word bank is: flower, owl, penguin, seaweed, sun — five items.

Blanks: 5 blanks total.

Chain 1: blank 1
Chain 2: blank 2
Chain 3: blank 3
Chain 4: blank 4
Chain 5: blank 5

We assigned:
- Chain 1: flower
- Chain 2: penguin
- Chain 3: owl
- Chain 5: seaweed

Left: sun

So chain 4 must be sun? But sun is not an organism, and the question says “missing organism”.

However, in the diagram, chain 4 does NOT have “sun” at the beginning — it starts with a blank. Whereas other chains do have “sun” drawn.

Perhaps for chain 4, they want us to put “sun” because it’s the ultimate source, even though it’s not an organism? But the example includes sun in the chain.

Looking back at the example: “Sun → grass → rabbit → fox” — so sun is part of the chain representation.

And the instruction says: “Fill in the missing organism in each food chain.” — but sun is not an organism.

This is confusing.

Alternative idea: Maybe in chain 4, the blank is for the producer that makes acorns — but since “oak tree” isn’t an option, and “flower” is already used, perhaps it’s a trick.

Wait — acorns are produced by oak trees, which are plants. Plants get energy from sun. But in the chain, if sun is not shown, maybe they expect “sun” to be filled in the blank for chain 4.

Moreover, in the word bank, “sun” is included, so likely it’s meant to be used for one of the blanks.

Let’s count how many times “sun” appears in the diagrams:

In the image, chains 1,2,3,5 have “sun” drawn at the start. Chain 4 does NOT have “sun” drawn — it starts with a blank.

Therefore, for chain 4, the blank is where “sun” should go, even though it’s not an organism — because the chain is incomplete without the energy source.

The example shows sun as part of the chain, so probably it’s acceptable.

Also, the word bank includes “sun”, so we must use it somewhere.

So let’s assign:

Chain 4: sun → acorn → squirrel → coyote

Even though sun is not an organism, it’s part of the food chain representation as per the example.

Then chain 5: we have seaweed left.

Chain 5: Sun → seaweed → fish → seal → shark

Yes, that works.

So final assignments:

Chain 1: flower
Chain 2: penguin
Chain 3: owl
Chain 4: sun
Chain 5: seaweed

But the question says “missing organism”, and sun is not an organism. However, given the context and the word bank, it seems necessary.

Perhaps in educational materials for grade 3, they include sun in the chain even when saying “organism” loosely.

To confirm, let’s see if there’s another way.

If we don’t use sun for chain 4, what else? None of the other words make sense before acorn.

So I think we have to go with sun for chain 4.

Thus:

Blank 1 (chain 1): flower
Blank 2 (chain 2): penguin
Blank 3 (chain 3): owl
Blank 4 (chain 4): sun
Blank 5 (chain 5): seaweed

Now, to present the answers in order as per the chains.

Final Answer:
flower, penguin, owl, sun, seaweed