Endoskeleton of sponge is called

Options

A. pinacoderm
B. mesoderm
C. choanoderm
D. none of these

Answer

To answer the question "Endoskeleton of sponge is called," we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Phylum**: Sponges belong to the phylum Porifera. Understanding the classification helps in knowing the characteristics of sponges.

2. **Understand the Structure**: The endoskeleton of sponges is not made up of traditional bones or cartilage but consists of a unique structure.

3. **Components of Endoskeleton**: The endoskeleton of sponges is primarily composed of calcareous spicules. These spicules are made of calcium carbonate and provide structural support.

4. **Terminology**: The endoskeleton is referred to as the "coenoderm" in sponges. This term specifically denotes the inner layer of the sponge's body.

5. **Differentiate Other Terms**:
- **Pinacoderm**: This is the outer layer of the sponge, made up of pinacocytes (flat cells).
- **Mesoderm**: This is not applicable to sponges as they are diploblastic, meaning they have only two germ layers (ectoderm and endoderm).
- **Coenoderm**: This is the correct term for the endoskeleton of sponges.

6. **Conclusion**: Therefore, the endoskeleton of a sponge is called "coenoderm."

### Final Answer:
The endoskeleton of sponge is called **coenoderm**.

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