Educational worksheet for identifying and comparing arthropods, focusing on crabs and spiders.

Let’s go step by step to solve this problem.

We are given three arthropods: a grasshopper, a crab, and a spider. For each one, we need to fill in the table with:

1. Name of Arthropod
2. Number of Legs
3. Structure Used for Breathing
4. How Many Sections? (Body sections)

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Step 1: Grasshopper

- The text says: “It has six legs.” → So, 6 legs
- It also says: “It breathes through tiny holes called spiracles on its body surface.” → So, breathing structure = spiracles
- We know from biology that insects like grasshoppers have 3 main body parts: head, thorax, abdomen → So, 3 sections

→ Grasshopper row:
Name: Grasshopper
Legs: 6
Breathing: Spiracles
Sections: 3

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Step 2: Crab

- Text says: “Crab has eight walking legs plus two claws which it uses for defense and catching food.”
→ Walking legs = 8, but claws are NOT counted as legs for movement. In arthropod classification, we usually count only the walking legs unless specified otherwise. But note: sometimes total appendages are considered — however, standard biology teaches crabs (as crustaceans) have 10 legs total (including claws). Let’s check carefully.

Actually, in most school-level biology, when they say “number of legs” for crabs, they mean the 8 walking legs + 2 claws = 10 total leg-like appendages. But let’s see what the question expects.

Looking at the diagram label: “Crab has eight walking legs plus two claws...” — so if we’re counting all leg-like structures used for locomotion or manipulation, it’s 10. However, strictly speaking, “legs” often refers to walking legs only. But in many curricula, crabs are said to have 10 legs (decapods).

Also, breathing: “Gills under its shell” → so breathing structure = gills

Body sections: Crustaceans like crabs have 2 main body parts: cephalothorax (head+thorax fused) and abdomen → so 2 sections

But wait — some sources say 3? No, crabs have cephalothorax and abdomen — that’s 2.

However, let’s double-check common teaching:

In elementary/middle school, crabs are often taught as having:
- 10 legs (including claws)
- Gills for breathing
- 2 body sections (cephalothorax and abdomen)

So we’ll go with that.

→ Crab row:
Name: Crab
Legs: 10 (8 walking + 2 claws — since claws are modified legs)
Breathing: Gills
Sections: 2

*(Note: If your teacher counts only walking legs, it would be 8 — but standard biological classification for decapods is 10 legs total. Since the text mentions “eight walking legs plus two claws”, and doesn’t specify to exclude claws, we include them as part of the leg count for arthropod identification purposes.)*

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Step 3: Spider

- Text says: “Spider has EIGHT jointed legs.” → So, 8 legs
- Breathing: “They breathe through book lungs and tracheae.” → So, breathing structure = book lungs and tracheae (we can write both, or just “book lungs” if simplifying — but better to include both as stated)
- Body sections: Spiders have 2 main parts: cephalothorax and abdomen → so 2 sections

→ Spider row:
Name: Spider
Legs: 8
Breathing: Book lungs and tracheae
Sections: 2

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Now let’s compile the table:

| Name of Arthropod | Number of Legs | Structure Used for Breathing | How Many Sections? |
|-------------------|----------------|----------------------------------|--------------------|
| Grasshopper | 6 | Spiracles | 3 |
| Crab | 10 | Gills | 2 |
| Spider | 8 | Book lungs and tracheae | 2 |

Wait — let me verify crab again. Some textbooks might say 8 legs for crab if they don’t count claws. But scientifically, crabs are decapods (“ten-footed”), so 10 is correct. Also, the problem says “eight walking legs plus two claws” — implying those are additional leg-like structures. Since the question asks for “number of legs” without specifying “walking”, and in arthropod context, claws are modified legs, 10 is accurate.

Also, for spider breathing — the text explicitly says “book lungs and tracheae”, so we should include both.

Final check:

Grasshopper: insect → 6 legs, spiracles, 3 body parts ✔️
Crab: crustacean → 10 legs (decapod), gills, 2 body parts (cephalothorax + abdomen) ✔️
Spider: arachnid → 8 legs, book lungs/tracheae, 2 body parts ✔️

All matches known biology.

Final Answer:

| Name of Arthropod | Number of Legs | Structure Used for Breathing | How Many Sections? |
|-------------------|----------------|----------------------------------|--------------------|
| Grasshopper | 6 | Spiracles | 3 |
| Crab | 10 | Gills | 2 |
| Spider | 8 | Book lungs and tracheae | 2 |