Moist cuticle is the respiratory organ in

Options

A. Insects
B. Earthworms
C. Aquatic arthropods and molluscs
D. Amphibians like frogs

Answer

To solve the question "Moist cuticle is the respiratory organ in," we will analyze each option provided and determine which organism utilizes a moist cuticle for respiration.

### Step 1: Understand the function of the cuticle
The cuticle is a protective layer that can also play a role in respiration in certain organisms. A moist cuticle allows for gas exchange through diffusion.

**Hint:** Consider the role of the cuticle in respiration and which organisms have a moist cuticle.

### Step 2: Analyze the options
1. **Insects**: Insects primarily use a system of air-filled tubes called trachea for respiration. Therefore, they do not rely on a moist cuticle for gas exchange.

**Hint:** Remember that insects have a specialized respiratory system that does not involve a moist cuticle.

2. **Earthworms**: Earthworms have a moist cuticle that facilitates gas exchange. Oxygen diffuses through their skin, which is covered by this moist cuticle, making it their primary respiratory organ.

**Hint:** Think about organisms that live in moist environments and how they breathe.

3. **Aquatic Arthropods**: Aquatic arthropods, such as crabs and shrimp, primarily use gills for respiration, not a moist cuticle.

**Hint:** Recall that gills are specialized structures for breathing in water.

4. **Molluscs**: Molluscs, like aquatic arthropods, also have gills for respiration. They do not use a moist cuticle for gas exchange.

**Hint:** Consider how aquatic animals typically breathe underwater.

5. **Amphibians (like frogs)**: Frogs primarily use lungs for respiration as adults, although they can also absorb some oxygen through their skin, but this is not through a moist cuticle in the same sense as earthworms.

**Hint:** Amphibians have a dual respiratory system, but they do not rely on a moist cuticle as their main organ for respiration.

### Step 3: Conclusion
After analyzing all the options, we find that the only organism that uses a moist cuticle as its respiratory organ is the **earthworm**. Therefore, the correct answer to the question is **earthworms**.

**Final Answer:** Earthworms have a moist cuticle that acts as their respiratory organ.