A radially symmetrical free swimming bioluminscent diploblastic marine orgnism is

Options

A. Sea fan
B. Sea pen
C. Sea walnut
D. Bath sponge

Answer

To solve the question "A radially symmetrical free swimming bioluminescent diploblastic marine organism is," we will analyze the characteristics given and the options provided.

### Step-by-Step Solution:

1. **Identify the Characteristics**:
- Radially symmetrical
- Free swimming
- Bioluminescent
- Diploblastic
- Marine organism

2. **Understand Radial Symmetry**:
- Radial symmetry means the organism can be divided into similar halves by multiple planes passing through the central axis. This characteristic is commonly found in organisms from the phyla Cnidaria (like jellyfish) and Ctenophora (like comb jellies), as well as Echinodermata (like starfish).

3. **Check for Free Swimming**:
- Free swimming indicates that the organism can move independently in the water, rather than being carried by currents. This feature is also present in Cnidarians and Ctenophores.

4. **Examine Bioluminescence**:
- Bioluminescence is the ability of an organism to produce light. This characteristic is specifically noted in Ctenophores, while it is not commonly found in Cnidarians or Echinoderms.

5. **Identify Diploblastic Organisms**:
- Diploblastic organisms have two germ layers: ectoderm and endoderm. Both Cnidarians and Ctenophores are diploblastic.

6. **Confirm Marine Habitat**:
- Marine organisms live in oceanic environments. Ctenophores are exclusively marine, while Cnidarians can be found in both marine and freshwater environments.

7. **Evaluate the Options**:
- **Sea Fan**: A type of Cnidarian; not free swimming.
- **Sea Pen**: A type of Cnidarian; not free swimming.
- **Sea Walnut**: A type of Ctenophore; free swimming, bioluminescent, diploblastic, and marine.
- **Bath Sponge**: A type of Porifera; not radially symmetrical and not free swimming.

8. **Conclusion**:
- The only organism that fits all the criteria of being radially symmetrical, free swimming, bioluminescent, diploblastic, and marine is the **Sea Walnut** (Ctenophora).

### Final Answer:
The radially symmetrical free swimming bioluminescent diploblastic marine organism is the **Sea Walnut**.

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