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(invertebrate zoology)
An intracellular effector organelle in the form of a coiled tube which may be rapidly everted in food gathering or defense by cnidarians.



(also stinging cell, nettling cell), a unique cell in the ectoderm and endoderm of most coelenterates (with the exception of ctenophorans) whose function is to attack prey and protect against enemies. A nematocyst contains a thin-walled capsule whose cavity contains a spirally coiled thread. The nucleus is situated at the base of the cell. A nematocyst has a sensory extension called a cnidocil projecting from the surface. When stimulated chemically or mechanically, the cnidocil forcefully ejects a straight, untwisted thread into the prey’s body. The sting kills small animals and sometimes causes painful burns and even death in large animals. A nematocyst can be used only once, after which it is discarded and replaced by a new one formed with specialized cells.

References in periodicals archive ?
Each data point represents a mean number of nematocysts counted per field of view for two replicate experiments, each consisting of eight test probes.
A guideline to nematocysts nomenclature and classification, and some notes on the systematic value of nematocysts.
The toxin isolated from nematocysts of Chrysaora is known to depolarise nerve and muscle membranes and to increase the frequency of miniature end-plate potentials.
Purification and partial characterization of the phospholipase A2 and co-lytic factor from sea anemone (Aiptasia pallida) nematocyst venom.
Evaluation of the effects of various chemicals on discharge of and pain caused by jellyfish nematocysts. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 151(4), 426-430.
Nematocysts were isolated from the dissected tentacles as described in a Bloom method with slight modification [25].
lactea cnidome (the set of nematocysts of a species) is well-known (Morandini & Marques, 2010) although there are no toxicological studies for this species.
Jellyfish sting using nematocysts, which are located in special cells called cnidocytes on the tentacles.
Several studies suggest that vinegar can counter the effects of the venomous nematocysts that a jellyfish releases during an attack.
These soft-bodied sea anemones provide a unique habitat for anemonefishes, which are protected from piscivorous fishes by the anemones' nematocysts. Furthermore, host anemones beneft from the presence of anemonefishes as they are aggressive against specialized anemone predators such as chaetodontids, and attack them more than they do non-predatory fishes in close vicinity (15).