What are parasites? Give examples.

Explanation

**Step-by-Step Solution:**

1. **Definition of Parasites**: Parasites are organisms that depend on another organism, known as the host, for their nutrition and survival. They are classified as heterotrophs because they cannot produce their own food.

2. **Dependency on Host**: Parasites rely entirely on their host for sustenance. They absorb nutrients from the host's body, which can lead to various health issues for the host.

3. **Types of Parasites**: There are two main types of parasites:
- **Ectoparasites**: These parasites live on the outside of the host's body. An example of an ectoparasite is lice, which inhabit hair follicles and feed on the host's blood.
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