Epidermis of chordates is

Options

A. Single layered
B. Transitional
C. Stratified
D. Absent

Answer

**Step-by-Step Solution:**

1. **Understanding the Epidermis**: The epidermis is the outermost layer of skin in chordates, which serves as a protective barrier.

2. **Origin of the Epidermis**: The epidermis is derived from the ectoderm, which is one of the three primary germ layers in the early embryo.

3. **Variability in Structure**: The structure of the epidermis in chordates can vary. In simpler chordates, such as protochordates (e.g., amphioxus), the epidermis is typically a single layer.

4. **Stratification in More Complex Chordates**: As we move up the evolutionary ladder to more complex chordates (like cyclostomes and mammals), the epidermis becomes stratified, meaning it consists of multiple layers of cells. For instance, mammals can have up to five layers of epidermis.

5. **Evaluating the Options**:
- **Single Layer**: This is true for protochordates but not for all chordates.
- **Transitional**: This option is incorrect as it does not accurately describe the epidermis of chordates.
- **Stratified**: This is correct for most chordates, especially the more complex ones.
- **Absent**: This is incorrect as chordates do have an epidermis.

6. **Conclusion**: Based on the analysis, the correct answer is that the epidermis of chordates is stratified.

**Final Answer**: The epidermis of chordates is stratified.

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