Hemichordates have close affinities with which of the following phylum

Options

A. Annelida
B. Arthropoda
C. Echinodermata
D. Mollusca

Answer

**Step-by-Step Solution:**

1. **Understand the Question**: The question asks which phylum has close affinities with hemichordates.

2. **Identify the Options**: The options provided are:
- Annelida
- Arthropoda
- Echinodermata
- Mollusca

3. **Analyze Hemichordates**: Hemichordates are a group of marine animals that share certain characteristics with other phyla.

4. **Determine Relationships**:
- Hemichordates are known to have close affinities with Echinodermata.
- This relationship is based on certain morphological and developmental similarities.

5. **Identify Key Similarities**:
- Both hemichordates and echinodermates exhibit bilateral symmetry in their larval forms.
- They both possess an enterocoelom, which is formed by the outpocketing of the gut wall (mesoderm pouches).

6. **Contrast with Other Options**:
- Annelida, Arthropoda, and Mollusca are classified as schizocoelomates.
- Schizocoelomates have a body cavity formed by the splitting of the mesoderm, which is different from the enterocoelom seen in hemichordates and echinodermates.

7. **Conclusion**: Based on the analysis, hemichordates are most closely related to Echinodermata.

**Final Answer**: Hemichordates have close affinities with the phylum Echinodermata.

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