Why are echinodermates called spiny-skinned animals?

Explanation

### Step-by-Step Solution

1. **Definition of Echinodermates**: Echinodermates belong to the phylum Echinodermata. This phylum includes marine animals such as starfish, sea urchins, and sea cucumbers.

2. **Reason for the Name**: The term "spiny-skinned" refers to the characteristic feature of these organisms. The bodies of echinodermates are covered with spines or spiny structures.

3. **Body Structure**: The spines are part of their unique body structure, which provides protection and contributes to their overall appearance. This spiny covering is made up of calcium carbonate and is a defining characteristic of the phylum.

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