Pharyngeal gill slits are dorsal in

Options

A. Cephalochordates
B. Urochordates
C. Hemichordates
D. Euchordates

Answer

To answer the question "Pharyngeal gill slits are dorsal in," we need to analyze the characteristics of different groups of chordates and identify where the pharyngeal gill slits are located.

### Step-by-Step Solution:

1. **Understanding Pharyngeal Gill Slits**:
- Pharyngeal gill slits are openings that appear along the pharynx in various organisms. They are primarily associated with filter feeding and respiration in aquatic animals.

2. **Identifying Groups of Chordates**:
- Chordates are divided into several groups, including hemichordates, cephalochordates, and urochordates. Each group has distinct characteristics regarding the presence and location of pharyngeal gill slits.

3. **Characteristics of Hemichordates**:
- Hemichordates are a group of invertebrate chordates that possess pharyngeal gill slits. In hemichordates, these slits are located dorsally.

4. **Characteristics of Cephalochordates and Urochordates**:
- Cephalochordates (e.g., lancelets) and urochordates (e.g., tunicates) also have pharyngeal gill slits, but they are not specifically noted for having them in a dorsal position. Instead, their gill slits are typically positioned differently during their life stages.

5. **Conclusion**:
- Based on the characteristics discussed, the correct answer to the question is that pharyngeal gill slits are dorsal in **hemichordates**.

### Final Answer:
Pharyngeal gill slits are dorsal in **hemichordates**.

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