Which group of phylum chordata has maximum living animals :-

Options

A. Pisces
B. Reptilia
C. Aves
D. Mammalia

Answer

To answer the question of which group of the phylum Chordata has the maximum number of living animals, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Phylum Chordata**:
- Phylum Chordata includes all animals that have a notochord at some stage of their development. This phylum is divided into several classes, including mammals, birds, reptiles, amphibians, and fishes.

2. **Identifying Major Groups**:
- The major groups within Chordata include:
- Mammals
- Birds
- Reptiles
- Amphibians
- Fishes (which can be further divided into classes like Osteichthyes and Chondrichthyes)

3. **Focusing on Fishes**:
- Among these groups, the class that contains the highest number of living species is the class of fishes, specifically the bony fishes (Osteichthyes). This class is characterized by having a bony skeleton and is known for its diversity.

4. **Comparing with Other Groups**:
- While mammals, birds, reptiles, and amphibians have a significant number of species, none of these groups come close to the sheer number of species found in bony fishes. For example, there are over 30,000 known species of bony fishes.

5. **Conclusion**:
- Therefore, the group within the phylum Chordata that has the maximum number of living animals is the class of bony fishes (Osteichthyes).

### Final Answer:
The group of phylum Chordata that has the maximum living animals is the class of bony fishes (Osteichthyes).

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