Flightless aquatic birds belong to

Options

A. Ratitae
B. Impennae
C. Carinatae
D. Odontognathae

Answer

To determine which group flightless aquatic birds belong to, we can analyze the options provided:

1. **Ratite**: This group includes flightless birds, such as ostriches and cassowaries. However, these birds are primarily adapted to land environments and are not aquatic.

2. **Impenae**: This group includes flightless aquatic birds that are adapted to life in the water. They possess features such as webbed feet and flipper-like wings, making them suitable for an aquatic lifestyle. Examples include penguins, which are well-known for being flightless and aquatic.

3. **Carinatae**: This group consists of birds that have a keel (carina) on their sternum, which serves as an attachment point for flight muscles. These birds are capable of flight, thus making this option incorrect for flightless aquatic birds.

4. **Odontoganathe**: This group refers to extinct birds that had teeth. They are not relevant to the question about flightless aquatic birds.

Based on this analysis, the correct answer is **Impenae**, as it specifically refers to flightless aquatic birds.

### Step-by-Step Solution:
1. **Identify the groups**: Look at the options provided (Ratite, Impenae, Carinatae, Odontoganathe).
2. **Analyze Ratite**: Understand that while Ratite includes flightless birds, they are not aquatic.
3. **Analyze Impenae**: Recognize that Impenae includes flightless aquatic birds adapted to water.
4. **Analyze Carinatae**: Note that Carinatae includes flying birds with a keel, making it incorrect.
5. **Analyze Odontoganathe**: Understand that this group consists of extinct birds, which is not relevant.
6. **Conclude the correct answer**: Based on the analysis, conclude that flightless aquatic birds belong to the group Impenae.