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trichocyst A bottle-shaped organelle, analogous to a nematocyst to which it bears a marked resemblance, that is found orientated at right angles to the cell surface in the pellicle of some members of the Ciliatea. Some trichocysts are explosive, discharging a thread-like shaft surmounted by a barb through a pore to the exterior, perhaps to capture prey or to anchor the ciliate during feeding. Other types of trichocyst are fluid-filled and discharge mucus and toxins.