Nematode

A nematode is an unsegmented, cylindrical worm in the phylum Nematoda. Nematodes occur in nearly every habitat, including soil, water, and living hosts.

Cuticle: A flexible external layer that protects an animal and can support its body. Nematodes shed this protective outer layer as they grow.
Caenorhabditis elegans: A small, transparent nematode widely used as a model organism in biology. Its mapped cell lineage and accessible genetics made it a landmark research species.
Ecdysozoa: A major animal group whose members grow by periodically shedding an external covering. Nematodes belong to this broad group alongside arthropods and several other phyla.
Pristionchus pacificus: A nematode used to study developmental evolution and interactions with insects. Its alternative mouth forms connect nematode development with feeding ecology.
Soil food web: The network of feeding relationships among organisms living in soil. Free-living nematodes occupy multiple feeding levels in soil communities.
Pseudocoelom: A fluid-filled body cavity that is not completely lined by mesoderm. This cavity helps support the nematode body and distributes internal materials.
Root-knot nematode: A plant-parasitic nematode in the genus Meloidogyne that induces galls on roots. Its root infections show how some nematodes cause major agricultural losses.
Tardigrade: A microscopic animal with eight legs, known for surviving extreme environmental conditions. Tardigrades are another ecdysozoan group, but have a segmented body and limbs.
Halicephalobus mephisto: A microscopic nematode discovered living deep within South African gold mines. Its discovery demonstrates that nematodes inhabit deep subsurface environments.
Nematode infection: Invasion and persistence of nematode parasites in a host organism. Parasitic nematodes cause disease in humans, livestock, wildlife, and plants.

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