an organ in coelenterates consisting of a minute capsule containing an ejectable thread that causes a sting.
nematocyst
British
/ nɪˈmætə-, ˈnɛmətəˌsɪst /
noun
a structure in coelenterates, such as jellyfish, consisting of a capsule containing a hollow coiled thread that can be everted to sting or paralyse prey and enemies
One of the minute capsules in the tentacles of cnidarians, such as jellyfish, hydras, or sea anemones, used for stinging. The capsule is produced by a special cell (called a cnidoblast) and contains a tightly coiled barbed thread that quickly shoots forth if the capsule's lid is disturbed. The thread often contains poison.