Animals which possess collar cells and an osculum as characteristics features belong to phylum :

Options

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

Answer

To solve the question regarding which phylum animals with collar cells and an osculum belong to, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Characteristics**:
- The question specifies two key features: collar cells and an osculum.
- Collar cells, also known as choanocytes, are specialized cells that help in the movement of water and food particles in certain animals.
- An osculum is a large opening in a sponge through which water exits.

2. **Evaluating the Options**:
- **Option 1: Cnidaria**:
- Cnidarians (like jellyfish and corals) are characterized by stinging cells (nematocysts) and do not have collar cells or an osculum.
- Therefore, this option is incorrect.

- **Option 2: Echinodermata**:
- Echinoderms (like starfish and sea urchins) have a hard spiny covering and a water vascular system, but they do not have collar cells or an osculum.
- Hence, this option is also incorrect.

- **Option 3: Ctenophora**:
- Ctenophores (like comb jellies) have bi-radial symmetry and ciliary plates for locomotion, but they lack collar cells and an osculum.
- This option is incorrect as well.

- **Option 4: Porifera**:
- Porifera, commonly known as sponges, are characterized by the presence of collar cells (choanocytes) and an osculum.
- They filter water through their bodies, allowing them to ingest food particles.
- This option is correct.

3. **Conclusion**:
- Based on the analysis of the characteristics of each phylum, the correct answer is **Option 4: Porifera**.

### Final Answer:
Animals which possess collar cells and an osculum as characteristic features belong to the phylum **Porifera**.