Nematocyst


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nematocyst

[nə′mad·ə‚sist]
(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.

Nematocyst

 

(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 ?
Histocompatibility effector system/competitive mechanism mediated by nematocyst discharge.
Hessinger, "Enzymatic characterization of the major phospholipase [A.sub.2] component of sea anemone (Aiptasia pallida) nematocyst venom," Toxicon, vol.
Analysis of soluble protein contents from the nematocysts of a model sea anemone sheds light on venom evolution.
Toxin compartmentation and delivery in the Cnidaria: the nematocyst's tubule as a multiheaded poisonous arrow.
Jellyfish have nematocysts, which are specialized venom-containing cells in the tentacles.
The epidermis is the outermost tissue layer and contains numerous nematocysts and cilia along the apical surface (Figs.
Vinegar as a disarming agent to prevent further discharge of the nematocysts of the stinging hydromedusa Olindias sambaquiensis.
During this process, the snails may be continually exposed to discharging nematocysts. Lovenella gracilis is equipped with microbasic mastigophores (Calder 1971), which can penetrate animal tissues and inject venom (Mariscal 1974, Purcell & Mills 1988).
Nematocyst compliment represented by microbasic b-mastigophores of two different sizes: (i) A-type: 5.5-7.2 [micron]m x 1.5-2.6 [micron]m; (ii) B-type: 7.5-9.8 [micron]m x 2.2-2.8 [micron]m.
We next focused on the morphology of nematocysts in tentacles and compared the size of stenoteles between strains 105G and 105.
Examination of discharged live nematocysts and comparison with the table of undischarged nematocysts published in Zagal et al.
Enzymatic characterization of the major phospholipase A sub(2) component of sea anemone (Aiptasia pallida) nematocyst venom.