Nematoda

Nematoda is a phylum of elongated, unsegmented worms with a complete digestive tract and a protective cuticle. Its members inhabit soil, freshwater, marine environments, and other organisms.

Cuticle: A tough external layer that protects an animal and may be periodically shed. Nematodes rely on a collagen-rich cuticle for protection and body support.
Hydrostatic skeleton: A support system in which fluid pressure and surrounding muscles maintain body shape and enable movement. Pressure in the pseudocoelom works with body-wall muscles to produce nematode motion.
Caenorhabditis elegans: A small, transparent nematode widely used in developmental biology and neuroscience. Its mapped cell lineage and nervous system make it a major experimental model.
Annelida: A phylum of segmented worms, including earthworms and leeches. Annelids have repeated body segments, unlike the unsegmented nematode body.
Ecdysis: The shedding of an old outer covering to permit growth or developmental change. Nematodes must molt their cuticle as they grow through successive stages.
Longitudinal muscle: Muscle fibers arranged along an animal's length that shorten or bend the body. Nematodes mainly use longitudinal muscles, producing characteristic side-to-side thrashing.
Plant-parasitic nematode: A nematode that feeds on plant tissues and can damage crops. Root-knot and cyst nematodes cause substantial agricultural losses.
Platyhelminthes: A phylum of dorsoventrally flattened worms, including tapeworms and planarians. Flatworms lack the complete digestive tract characteristic of nematodes.
Pseudocoelom: A fluid-filled body cavity not completely lined by mesoderm. This cavity supports internal organs and helps transmit pressure through the nematode body.
Nematode feeding: The varied ways nematodes obtain food, including consuming microbes, plants, and animals. Mouth structures and feeding habits vary widely across the phylum.

Linked from 10 pages