Nematodes puncture the cell walls of plant roots with (sometimes large) hollow needle-like stylets in their mouths and suck out plant nutrients.
The stylets vary in shape. Enzymes, (e.g. cellulase and chitinase) are injected through the stylets of some plant parasitic species to help break down cell walls.
Head of Globodera pallida with an extendable stylet used to penetrate roots of host plant species, such as potatoes (Solanum tuberosum). Note the anchor shaped knobs at the base of the stylet with muscles extending forward to the head. When these muscles contract, the stylet moves forward.