Identify the following parasites and the phylum to which they belong.
It resides in the stomach of humans and causes itching anus and stomach ache.

Explanation

**Step-by-Step Solution:**

1. **Identify the Symptoms**: The question describes a parasite that resides in the stomach of humans and causes itching in the anus and stomach ache. These symptoms are indicative of a parasitic infection.

2. **Recognize the Parasite**: Based on the symptoms provided, the parasite that matches this description is the hookworm. Hookworms are known to cause gastrointestinal issues, including stomach pain and itching around the anus.

3. **Scientific Name**: The scientific name for the hookworm commonly found in humans is *Necator americanus*. This species is one of the most prevalent hookworms affecting humans.

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