Pinworm

The human gastrointestinal tract, specifically the large intestine and rectum; eggs are often found on bedding and surfaces in modern indoor environments.

Absorbs nutrients and organic matter from the intestinal contents of the human host.

Nocturnal migration where gravid females move to the perianal area to lay thousands of eggs, causing intense itching. The life cycle completes when eggs are ingested through the mouth.

Causes enterobiasis, characterized by anal itching and restless sleep. While not generally dangerous, they are highly contagious in households and schools; they provide no known ecosystem benefits.