has part in taxon secretory cell eukaryotic cell cnidocyte cnidoblast An explosive cell containing one giant secretory organelle called a cnidocyst (also known as a cnida (plural cnidae) or nematocyst) that contains a toxin responsible for the stings delivered by a cnidarian to other organisms. Cnidae are used to capture prey and as a defense against predators. The presence of cnidocytes defines the phylum Cnidaria (corals, sea anemones, hydrae, jellyfish, etc.). nematocyte nematocyst Cnidaria