Classification of Phylum Porifera is based on

Options

A. branching spicules
B. spicules
C. reproduction
D. symmetry

Explanation

**Step-by-Step Text Solution:**

1. **Introduction to Phylum Porifera**:
- Phylum Porifera is one of the simplest phyla in the animal kingdom and includes organisms commonly known as sponges. They are classified as invertebrates and are considered to be among the earliest evolved animal groups.

2. **Species Count**:
- There are over 8,500 known species within the phylum Porifera, indicating a diverse range of sponge organisms.

3. **Basis of Classification**:
- The classification of Porifera is primarily based on the presence and type of skeletal structures known as spicules.

4. **Understanding Spicules**:
- Spicules are hard, crystallized structures that serve as the skeleton for sponges. They can vary in shape, size, and composition, which is crucial for their classification.

5. **Options Analysis**:
- When analyzing the options provided for the classification basis:
- Option 1: Branching spicules - Incorrect.
- Option 2: Spicules - Correct answer.
- Option 3: Reproduction - Incorrect.
- Option 4: Symmetry - Incorrect.

6. **Conclusion**:
- The correct basis for the classification of Phylum Porifera is the presence and type of spicules. Therefore, the answer is option 2: spicules.

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