Which of the following is a correct sequence of decreasing order of number of species ?

Options

A. Aves, pisces, reptiles, amphibians,
mammals
B. Pisces, aves, reptiles, mammals, am-
phibians
C. Pisces, mammals, reptiles, mammals, aves
D. Amphibians, aves, pisces, mammals,
reptiles

Answer

To determine the correct sequence of decreasing order of the number of species among the given groups (Pisces, Aves, Reptiles, Mammals, and Amphibians), we need to analyze the diversity of species within each group.

### Step 1: Identify the Groups
The groups we are considering are:
- Pisces (fishes)
- Aves (birds)
- Reptiles
- Mammals
- Amphibians

### Step 2: Understand the Diversity in Each Group
1. **Pisces (Fishes)**: This group is known to have the highest number of species among all vertebrates. There are thousands of species of fish, including bony fish (Osteichthyes) and cartilaginous fish (Chondrichthyes).

2. **Aves (Birds)**: Birds are also diverse, but they have fewer species compared to fishes. There are around 10,000 species of birds worldwide.

3. **Reptiles**: This group includes snakes, lizards, turtles, and crocodiles. The total number of reptile species is significantly lower than that of fishes and birds, with around 10,000 species.

4. **Mammals**: Mammals are more evolved and have around 5,500 species. They include a wide variety of animals but are fewer in number compared to the previous groups.

5. **Amphibians**: This group includes frogs, toads, and salamanders. Amphibians have the least number of species among these groups, with about 7,000 species.

### Step 3: Arrange the Groups in Decreasing Order
Based on the analysis of species diversity:
1. **Pisces** (most species)
2. **Aves**
3. **Reptiles**
4. **Mammals**
5. **Amphibians** (least species)

### Conclusion
The correct sequence of decreasing order of the number of species is:
**Pisces > Aves > Reptiles > Mammals > Amphibians**

### Final Answer
The correct option is: **Pisces, Aves, Reptiles, Mammals, Amphibians.**

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