nematoides

Nematoides, also known as nematodes, are a diverse group of roundworms that belong to the phylum Nematoda. They are usually small, elongated, and tapered at both ends, with a simple body plan that includes a tubular digestive system and a pseudocoelom.

They inhabit nearly every environment on Earth, from soil and freshwater to marine habitats. Free-living species often act as decomposers or predators, while many others are parasites of plants, animals, or humans. Nematodes play key roles in soil health and nutrient cycling.

Life cycle and biology: Most species reproduce sexually, with separate sexes in many groups, though some are hermaphroditic or parthenogenetic. Development typically includes several larval stages (L1 to L4) before reaching adulthood. Sizes range from less than a millimeter to several centimeters.

Economic and medical relevance: Plant-parasitic nematodes such as root-knot nematodes (Meloidogyne) and cyst nematodes (Heterodera, Globodera) cause substantial crop losses. Parasitic nematodes also affect livestock and humans, including Ascaris, Trichuris, and hookworms. Beneficial species contribute to nutrient turnover and biological control.

In research, the free-living species Caenorhabditis elegans serves as a widely used model organism for studies in development, genetics, and neuroscience. Management of nematode problems relies on crop resistance, soil health, proper sanitation, and chemical or biological controls.