Name anti-coagulant in the saliva of leech.

Explanation

**Step-by-Step Solution:**

1. **Identify the Organism**: The question asks about an anticoagulant found in the saliva of a specific organism, which is the leech.

2. **Understand the Function of Anticoagulants**: Anticoagulants are substances that prevent blood from clotting. This is crucial for organisms that feed on blood, as clotting would obstruct their feeding process.

3. **Name the Anticoagulant**: The anticoagulant present in the saliva of leeches is called **Hirudin**.

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