| Only cnidarians manufacture microscopic intracellular stinging capsules, known as nematocysts or cnidae, which give the phylum its name. |
| Among the most remarkable are the nudibranchs that eat anemones and hydroids and then sequester certain types of immature, undischarged cnidae from the prey. |
| Cnidae are among the most complex intracellular secretion products known. |
| Nematocysts are a type of cnidae, and it is the presence of cnidae that separates jellyfish and other cnidarians from other animals. |
| However, unlike cnidarians, ctenophores possess rows of cilia and a unique, complex sensory organ and lack cnidae and metagenesis. |
| Once the cnidae have matured within the nudibranch, they can be used in its own defense. |
