Nematode (Roundworm)
Scientific Name: Nematoda (Phylum)
Order & Family: Order: Nematoda (Phylum); Family: Highly diverse, varies by species
Size: Most nematodes are microscopic, ranging from 0.05 mm to 5 mm in length. Some parasitic species can grow much larger, up to several meters (e.g., horsehair worms, which are sometimes confused with nematodes but are in a different phylum, or certain whale parasites).
Natural Habitat
Nematodes are ubiquitous and can be found in nearly every environment on Earth. They are particularly abundant in soil (both terrestrial and aquatic), freshwater, marine environments, and as parasites within plants and animals.
Diet & Feeding
The diet of nematodes is highly diverse depending on the species. Many are decomposers, feeding on bacteria, fungi, and decaying organic matter. Some are predators of other small invertebrates, while others are plant parasites or animal parasites, including those that parasitize humans.
Behavior Patterns
Nematodes move in characteristic undulating, s-shaped patterns. Many species are free-living in soil or water, feeding on bacteria, fungi, or other microorganisms. Parasitic species have complex life cycles involving hosts. Their activity is often dependent on moisture levels.
Risks & Benefits
Risks: Many species are significant agricultural pests, causing damage to crops. Some nematodes are parasites of humans and animals, causing diseases such as ascariasis, hookworm, and trichinosis. Benefits: Free-living nematodes are crucial decomposers, playing a vital role in nutrient cycling in soil. Some species are used as biological control agents against insect pests.
Identified on: 8/31/2025