Exoskeleton of echinodermis is

Options

A. Calcareous
B. Siliceous
C. Tunicin
D. Chitinous

Answer

To answer the question "Exoskeleton of echinodermis is," we will analyze the given options one by one and determine which material is used for the exoskeleton of echinoderms.

### Step-by-Step Solution:

1. **Understanding Echinoderms**:
- Echinoderms are a group of marine animals that include starfish, sea urchins, and sea cucumbers. They are known for their unique body structure and are classified under the phylum Echinodermata.

2. **Analyzing the Options**:
- The options provided are:
1. Calcareous
2. Siliceous
3. Tunicin
4. Chitinous

3. **Option 1: Calcareous**:
- Calcareous exoskeletons are made of calcium carbonate. This type of exoskeleton is indeed found in echinoderms. It provides structural support and protection.

4. **Option 2: Siliceous**:
- Siliceous exoskeletons are primarily found in organisms like diatoms and some sponges. This option does not apply to echinoderms.

5. **Option 3: Tunicin**:
- Tunicin is a cellulose-like substance found in the tunicates (urochordates). It is not related to echinoderms.

6. **Option 4: Chitinous**:
- Chitinous exoskeletons are characteristic of arthropods (like insects and crustaceans). This option is also not applicable to echinoderms.

7. **Conclusion**:
- After analyzing all the options, we find that the correct answer is **Calcareous**. The exoskeleton of echinoderms is made up of calcareous material.

### Final Answer:
The exoskeleton of echinodermis is **Calcareous**.

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