Diploblastic, aquatic animals with tissue level of organisation belong to the Phylum

Options

A. Protozoa
B. Porifera
C. Cnidaria
D. Helminthes

Explanation

To solve the question regarding which phylum diploblastic, aquatic animals with tissue level of organization belong to, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Diploblastic**: This means that the organism has two germ layers: ectoderm and endoderm.
- **Aquatic**: This indicates that the organisms live in water.
- **Tissue Level of Organization**: This means that the cells are organized into tissues, which is a higher level of organization than just cellular.

2. **Analyzing the Options**:
- **Protozoa**: These are single-celled organisms and do not belong to the animal kingdom in the context of multicellular organisms. They are not diploblastic or tissue-organized.
- **Porifera**: Commonly known as sponges, these organisms have a cellular level of organization, not tissue level. Therefore, they do not fit the criteria.
- **Cnidaria**: This phylum includes jellyfish, corals, and sea anemones. They are aquatic, exhibit radial symmetry, are diploblastic (having ectoderm and endoderm), and have a tissue level of organization.
- **Helminthes**: These are flatworms and roundworms, which are triploblastic (having three germ layers: ectoderm, endoderm, and mesoderm). Thus, they do not meet the criteria of being diploblastic.

3. **Conclusion**:
- Based on the analysis, the only phylum that fits all the criteria of being diploblastic, aquatic, and having a tissue level of organization is **Cnidaria**.

### Final Answer:
Diploblastic, aquatic animals with tissue level of organization belong to the Phylum **Cnidaria**.