expskeleton, a characteristic feature of reptilia is absent in

Options

A. fish
B. aves
C. mammals
D. amphibians

Answer

**Step-by-Step Solution:**

1. **Understanding Exoskeleton**:
- An exoskeleton is defined as an external skeleton that provides support and protection to an animal's body. It is a characteristic feature found in various animal groups, particularly in reptiles.

2. **Analyzing the Options**:
- **Option 1: Fishes**: Fishes have scales that can be considered a form of exoskeleton. Therefore, this option is incorrect.
- **Option 2: Eggs**: Eggs themselves do not have an exoskeleton as they are not animals. This option is also incorrect.
- **Option 3: Mammals**: Mammals possess hair, which is a type of epidermal exoskeleton. Thus, this option is incorrect as well.
- **Option 4: Amphibians**: Amphibians have smooth, moist skin that is well-vascularized and serves respiratory functions. They do not have scales or a traditional exoskeleton, making this option correct.

3. **Conclusion**:
- The exoskeleton, a characteristic feature of reptiles, is absent in amphibians. Therefore, the correct answer is **Option 4: Amphibians**.

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