Nervous system of ctenophores is similar to

Options

A. Cnidaria
B. Platyhelminthes
C. Nemathelminthes
D. Annelida

Answer

To determine the similarity of the nervous system of ctenophores, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Nervous System of Ctenophores**:
- Ctenophores, also known as comb jellies, possess a nervous system that is characterized as being diffuse or decentralized. This means that it does not have a centralized brain but rather a network of nerve cells.

2. **Compare with Other Phyla**:
- To find a similar nervous system, we need to look at other phyla. The main candidates to consider are:
- Phylum Cnidaria (which includes jellyfish, corals, and sea anemones)
- Phylum Platyhelminthes (flatworms)
- Phylum Nematoda (roundworms)
- Phylum Annelida (segmented worms)

3. **Analyze the Nervous System of Cnidaria**:
- The nervous system in Cnidaria is also a diffuse network of nerve cells, similar to that of ctenophores. This primitive type of nervous system allows for basic responses to stimuli.

4. **Examine Other Phyla**:
- **Platyhelminthes**: They have a ladder-like nervous system with a centralized brain and longitudinal nerve cords, which is different from ctenophores.
- **Nematoda**: Their nervous system consists of a circumpharyngeal ring and is also more centralized than that of ctenophores.
- **Annelida**: They have a more complex nervous system with a nerve ring and ventral nerve cords, which again is different from ctenophores.

5. **Conclusion**:
- Given that the nervous system of ctenophores is most similar to that of Cnidaria, we conclude that the correct answer is **Phylum Cnidaria**.

### Final Answer:
The nervous system of ctenophores is similar to that of **Phylum Cnidaria**.