Practice question

Stinging organelles unique to Cnidaria called nematocysts or cnidocysts housed within specialized epidermal cells termed cnidocytes derived from interstitial stem cells concentrated densest on tentacles oral disc. Each nematocyst consists of capsule containing coiled hollow harpoon thread bathed in toxin triggered to evert explosively penetrating prey. Multiple types penetrant glutinant adhesion volvent entangling. Formation involves Golgi synthesis. Distinguishing synapomorphy of phylum Cnidaria giving group name absent in Porifera and Ctenophora which possess adhesive colloblasts not stinging for prey capture mechanisms evolutionarily distinct and highly specialized for predation and defense in cnidarians with toxic venom systems widely studied.