Which of the following Phyla has largest number of species ?

Options

A. Arthropoda
B. Echinodermata
C. Cephalochordata
D. Annelida

Answer

To determine which phylum has the largest number of species, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Phyla Listed**: We have four options to consider:
- Option 1: Arthropoda
- Option 2: Echinodermata
- Option 3: Cephalocordata
- Option 4: Annelida

2. **Understand the Classification**: The question pertains to the classification of animals into different phyla. The animal kingdom (Kingdom Animalia) consists of several phyla, each with varying numbers of species.

3. **Research the Number of Species in Each Phylum**:
- **Arthropoda**: This phylum includes insects, arachnids, crustaceans, and more. It is known to contain approximately 75% of all known animal species, making it the largest phylum.
- **Echinodermata**: This phylum includes starfish, sea urchins, and sea cucumbers. It has far fewer species compared to Arthropoda.
- **Cephalocordata**: This phylum includes lancelets, which are small, fish-like marine animals. It has a very limited number of species.
- **Annelida**: This phylum includes segmented worms like earthworms and leeches. While it has a significant number of species, it is still less than that of Arthropoda.

4. **Conclusion**: Based on the research, it is clear that Arthropoda has the largest number of species among the given options.

5. **Final Answer**: Therefore, the phylum with the largest number of species is **Arthropoda** (Option 1).