Animals that do not possess a backbone are called ……….

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the term used to describe animals that do not have a backbone.

2. **Identifying Backbone Animals**: We know that animals with a backbone are called vertebrates. This includes humans and many other species.

3. **Defining the Opposite**: Since the question is about animals without a backbone, we need to find the term that represents the opposite of vertebrates.

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