The members of following phylum are exclusively marine, radially symmetrical and diploblastic

Options

A. Porifera
B. Echinodermata
C. Ctenophora
D. Hemichordata

Answer

To solve the question regarding which phylum consists of exclusively marine, radially symmetrical, and diploblastic organisms, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Characteristics**:
- **Exclusively Marine**: The organisms must live only in marine environments (oceans and seas).
- **Radially Symmetrical**: The body can be divided into similar halves by multiple planes passing through a central axis.
- **Diploblastic**: The body is made up of two embryonic germ layers: ectoderm and endoderm.

2. **Evaluating the Options**:
- **Option 1: Porifera**:
- While Porifera (sponges) are exclusively marine, they are not radially symmetrical; they are typically asymmetrical. They are diploblastic, but the lack of radial symmetry eliminates this option.
- **Option 2: Echinodermata**:
- Echinoderms (like starfish and sea urchins) are exclusively marine, exhibit radial symmetry as adults, and are diploblastic. This option fits all criteria.
- **Option 3: Hemichordata**:
- Hemichordates are primarily marine but exhibit bilateral symmetry, not radial symmetry. Thus, this option does not meet the criteria.

3. **Conclusion**:
- Based on the evaluation, the only phylum that meets all the criteria of being exclusively marine, radially symmetrical, and diploblastic is **Echinodermata**.

### Final Answer:
The phylum that is exclusively marine, radially symmetrical, and diploblastic is **Echinodermata**.