Final answer:
Free-living worms are non-parasitic worms that hunt or scavenge for food, unlike parasitic worms which feed off a host. These types of worms are often found in aquatic or moist soil habitats.
Step-by-step explanation:
The term we use for worms that are not parasitic is free-living. Unlike parasitic worms, such as the heartworm Dirofilaria immitis that feeds off its host, free-living worms do not rely on a host for survival. Free-living worms, including some flatworm species, are predators or scavengers that eat other small invertebrates and decaying animals. Most of these species prefer aquatic habitats, but some adapt to moist soil environments. Contrary examples include parasitoids, such as some fungi or insects that reproduce obligately through a trophic event that results in the eatee's death, and saprotrophs, organisms like bacteria feeding on decaying organic material.