Those parasites which take their food only from living hosts are known as …................... parasites.

Explanation

**Step-by-Step Solution:**

1. **Understand the Definition of Parasites**: A parasite is an organism that lives in or on a host organism and derives its food and nourishment from the host.

2. **Identify the Types of Parasites**: There are two main types of parasites:
- **Obligatory Parasites**: These parasites are entirely dependent on their host for food and other forms of nourishment.
- **Facultative Parasites**: These parasites can live independently of a host and do not rely solely on the host for their nourishment.

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