How many animals in the given list have gills for respiration ?
Earthworm , Frog, Fish, Insects, Reptiles, Aquatic arthropods, Flatworm, Molluscs, Birds

Options

A. Six
B. Four
C. Three
D. Five

Answer

To determine how many animals in the given list have gills for respiration, we need to analyze each animal one by one:

1. **Earthworm**: Earthworms respire through their skin (cutaneous respiration) and do not have gills.
- **Hint**: Remember that earthworms rely on skin for gas exchange.

2. **Frog**: Frogs primarily respire through their skin and lungs as adults. They do have gills during their larval stage (tadpoles), but as adults, they do not use gills for respiration.
- **Hint**: Consider the life cycle of frogs and their respiratory adaptations at different stages.

3. **Fish**: Fish have gills, which are specialized organs for extracting oxygen from water.
- **Hint**: Fish are well-known for their gill-based respiration.

4. **Insects**: Insects do not have gills; they have a tracheal system for respiration.
- **Hint**: Think about how insects breathe and their unique respiratory system.

5. **Reptiles**: Reptiles primarily use lungs for respiration and do not have gills.
- **Hint**: Reptiles are air-breathing animals.

6. **Aquatic Arthropods**: Many aquatic arthropods, such as crabs and shrimp, have gills for respiration.
- **Hint**: Aquatic arthropods are often found in water and have adaptations for breathing in that environment.

7. **Flatworm**: Flatworms typically respire through their skin and do not have gills.
- **Hint**: Flatworms are simple organisms that rely on diffusion for gas exchange.

8. **Molluscs**: Many molluscs, such as clams and octopuses, have gills for respiration.
- **Hint**: Molluscs are diverse, and many of them are aquatic with gills.

9. **Birds**: Birds have lungs for respiration and do not have gills.
- **Hint**: Birds are adapted for flight and have a unique respiratory system involving lungs.

Now, let's summarize the findings:

- **Animals with gills**:
- Fish
- Aquatic Arthropods
- Molluscs

Thus, there are **3 animals** in the given list that have gills for respiration.

### Final Answer:
**3 animals have gills for respiration.**