Teleost fishes are characterized by the presence of

Options

A. Air bladder
B. Claspers
C. Cloaca
D. Cartilaginous endoskeleton

Answer

**Step-by-Step Solution:**

1. **Understanding Teleost Fishes**: Teleost fishes are commonly known as bony fishes. They belong to the class Actinopterygii and are characterized by having a bony skeleton as opposed to a cartilaginous skeleton found in cartilaginous fishes like sharks and rays.

2. **Differentiating Between Fish Types**:
- **Cartilaginous Fishes**: These fishes have a skeleton made of cartilage. They typically have a ventral mouth (facing downwards) and lack air bladders, which means they must constantly swim to maintain buoyancy.
- **Bony Fishes (Teleosts)**: In contrast, bony fishes have a skeleton made of bone, a terminal mouth (located at the end of the head), and possess air bladders that help them maintain buoyancy in water.

3. **Identifying Key Characteristics of Teleost Fishes**:
- One of the defining features of teleost fishes is the presence of an air bladder. This organ allows them to control their buoyancy, enabling them to float at various depths without expending much energy.

4. **Evaluating the Options**:
- The options provided include:
- Air bladder
- Claspers
- Cloaca
- Cartilaginous endoskeleton
- Among these, the presence of an air bladder is the characteristic feature of teleost fishes. Claspers are found in some cartilaginous fishes, cloaca is associated with amphibians, and cartilaginous endoskeleton pertains to cartilaginous fishes.

5. **Conclusion**: Therefore, the correct answer to the question about what teleost fishes are characterized by is the presence of an air bladder.

**Final Answer**: Teleost fishes are characterized by the presence of an air bladder.

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