Which of the following class of animals have a two chambered heart?

Options

A. Reptiles
B. Birds
C. Fishes
D. Mammals

Answer

To determine which class of animals has a two-chambered heart, we can analyze the heart structure of the given options: reptiles, birds, fishes, and mammals.

### Step-by-Step Solution:

1. **Understand Heart Structure**:
- The heart can have different numbers of chambers. The basic types are:
- Two-chambered heart: One atrium and one ventricle.
- Three-chambered heart: Two atria and one ventricle.
- Four-chambered heart: Two atria and two ventricles.

2. **Analyze Each Class of Animals**:
- **Mammals**: Mammals have a four-chambered heart, which consists of two atria and two ventricles. This structure allows for efficient separation of oxygenated and deoxygenated blood.
- **Birds**: Birds also have a four-chambered heart, similar to mammals, which helps in their high metabolic demands.
- **Reptiles**: Most reptiles have a three-chambered heart, which includes two atria and one ventricle. However, some reptiles like crocodiles have a more complex heart structure that can function similarly to a four-chambered heart.
- **Fishes**: Fishes have a two-chambered heart, consisting of one atrium and one ventricle. This is the simplest heart structure among the classes listed.

3. **Identify the Correct Answer**:
- Based on the analysis, the class of animals that has a two-chambered heart is **fishes**.

### Final Answer:
**Fishes have a two-chambered heart.**

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