1. Specialized stinging cells found in jellyfish, sea anemones, and other cnidarians that contain a coiled, venomous harpoon-like structure used to capture prey and defend against predators.
Usage: plural of nematocyst; biology/marine science term; also called cnidocytes in modern usage

Examples

• Jellyfish use nematocysts to paralyze small fish and plankton.
• The nematocysts of sea anemones can cause painful stings to swimmers.
• When a nematocyst fires, it ejects a barbed filament at high speed.
• Coral polyps rely on nematocysts to capture food from the water column.
• The venom in nematocysts varies greatly depending on the species of cnidarian.