Which of the phylum contains exclusively marine, radially symmetrical , diploblastic organisms with the tissue level organization ?

Options

A. Platyhelminthes
B. Ctenophora
C. Arthropoda
D. Annelida

Answer

To solve the question, "Which of the phylum contains exclusively marine, radially symmetrical, diploblastic organisms with tissue level organization?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Key Terms**:
- **Marine**: Refers to organisms that live in the ocean.
- **Radially Symmetrical**: Organisms that can be divided into similar halves by multiple planes passing through a central axis.
- **Diploblastic**: Refers to organisms that have two germ layers: ectoderm and endoderm.
- **Tissue Level Organization**: Indicates that the cells are organized into tissues.

2. **Analyzing the Options**:
- **Option 1: Platyhelminthes**:
- These are flatworms, which are primarily bilateral in symmetry and triploblastic (having three germ layers). Thus, this option is incorrect.

- **Option 2: Cnidaria** (not mentioned in the transcript but relevant):
- Cnidarians, such as jellyfish and corals, are marine, radially symmetrical, and diploblastic with tissue-level organization. This option seems to fit the criteria.

- **Option 3: Arthropoda**:
- This phylum includes insects, arachnids, and crustaceans, which exhibit bilateral symmetry and are triploblastic. Thus, this option is incorrect.

- **Option 4: Annelida**:
- Annelids, such as earthworms, also show bilateral symmetry and are triploblastic. Therefore, this option is incorrect.

3. **Conclusion**:
- The correct answer is **Cnidaria**, which contains exclusively marine, radially symmetrical, diploblastic organisms with tissue level organization.

### Final Answer:
The phylum that contains exclusively marine, radially symmetrical, diploblastic organisms with tissue level organization is **Cnidaria**.