A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a cnidocyst, that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ejects the toxin -containing cnidocyst which is responsible for the stings delivered by a cnidarian.

The stings are caused by tiny capsules called cnidae (singular: cnida), which contain a coiled tubule and venom. In medusae, most cnidae are located in and around the tentacles and/or oral arms, although some cnidae are also found in the bell.

Cnidae are organelle-like capsules with eversible tubules (they shoot the tubule outwards). [2] They are the diagnostic feature of the phylum. All cnidarians possess cnidae; no loss of the feature is known. There are three main types of cnidae: nematocysts, ptychocysts, and spirocysts, with many variations.

Cnidaria (/ nɪˈdɛəriə, naɪ -/ nih-DAIR-ee-ə, ny-) [4] is a phylum under kingdom Animalia containing over 11,000 species [5] of aquatic invertebrates found both in freshwater and marine environments (predominantly the latter), including jellyfish, hydroids, sea anemones, corals and some of the smallest marine parasites.

Cnidarians are the oldest extant lineage of venomous animals. Despite their simple anatomy, they are capable of subduing or repelling prey and predator species that are far more complex and recently evolved.

Members of the Phylum Cnidaria are characterized by the possession of cnidae, those curious, everting, intracellular organelles that have both startled and intrigued humans for thousands of years.

Mar 22, 2025 · Cnidae range from only about 10 to 100 micrometres (0.0004 to 0.004 inch) long, but they are among the most complex intracellular secretion products known. Each consists of a spherical or cigar-shaped capsule with an eversible, hollow tubule extending from one end.

Mar 1, 2014 · There are over 30 known types of morphologically distinct cnidae that are divided in three functional groups: pierce, entangle or adhere to prey. Thus, cnidae are the chief instruments, by which...

Mar 22, 2025 · cnidarian, any member of the phylum Cnidaria (Coelenterata), a group made up of more than 9,000 living species. Mostly marine animals, the cnidarians include the corals, hydras, jellyfish, Portuguese men-of-war, sea anemones, sea pens, sea whips, and sea fans.

Dec 15, 2009 · Of the three categories of cnidae (also called cnidocysts), nematocysts occur in all cnidarians, and are the means by which cnidarians defend themselves and obtain prey; spirocysts and ptychocysts are restricted to a minority of major taxa.