nematocyst


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Related to nematocyst: basal disc

nem·a·to·cyst

(nem'ă-tō-sist),
A stinging cell of coelenterates consisting of a poison sac and a coiled barbed sting capable of being ejected and penetrating the skin of an animal on contact; of considerable consequence in large jellyfish and in the Portuguese man-of-war which possess large numbers of these stinging cells that can cause great pain and even death.
Synonym(s): cnida, cnidocyst
[nemato- + G. kystis, bladder]

nematocyst

(nĕm′ə-tə-sĭst′, nĭ-măt′ə-)
n.
A capsule within specialized cells in the tentacles of cnidarians, such as jellyfish and corals, containing a barbed, threadlike tube that delivers a toxic sting to predators and prey.

nem′a·to·cys′tic adj.

nematocyst

[nem′ətōsist′]
Etymology: Gk, nema, thread, eidos, form, kystis, bag
a capsule containing a barbed, threadlike process found in certain cells on the external surface of cnidarians, such as the Portuguese man-of-war and jellyfish. The nematocysts of some cnidarians can penetrate the skin and inject a poison, causing painful and potentially fatal injury.

nem·a·to·cyst

(nem'ă-tō-sist)
A stinging cell of coelenterates consisting of a poison sac and a coiled barbed sting capable of being ejected and penetrating the skin of an animal on contact; of considerable consequence in large jellyfish and in the Portuguese man-of-war whose large numbers of these stinging cells can cause great pain and even death.
[nemato- + G. kystis, bladder]

nematocyst

A coiled, tube-like stinging organ of various coelenterates, such as jellyfish. The nematocyst injects a chemical paralyzant.
Nematocystclick for a larger image
Fig. 227 Nematocyst . Nematocysts of Hydra. (a) Discharged. (b) Undischarged.

nematocyst

a structure formed of a hollow thread within a bladder in the CNIDOBLAST or thread cell of COELENTERATES. On stimulation, for example by prey, the thread is everted. Several types exist, such as stinging cells that inject poisonous substances into the prey through the thread, and sticky cells which exude a sticky substance which causes the prey to adhere to the coelenterate tentacle. Enormous numbers are present on the tentacles of some forms and nematocysts are responsible for the jellyfish ‘sting’. Such cells can be utilized by other organisms, for example flatworms preying on coelenterates. The nematocysts migrate to the surface layer of a flatworm which has fed on the coelenterate and are used by the flatworms in exactly the same way as coelenterates use them.
References in periodicals archive ?
Nematocyst compliment represented by microbasic b-mastigophores of two different sizes: (i) A-type: 5.
When nematocysts were deactivated, the pompano failed to discriminate between clams with and without hydroids, suggesting that nematocysts are responsible for deterring this predator.
I would like to thank Robert Burn and Melanie Mackenzie for their assistance with collecting specimens, Claudia Mills for the many emails about these animals, Jeanette Watson for teaching me how to examine the nematocysts, John Kuo for kindly sending me his paper on Heterozostera, Hugh Kirkman for confirming the species of seagrass present at the Jawbone and, finally, Leon Altoff for kneeling for long periods in very cold water in the middle of winter to capture images.
When attacking anemones, shrimp were prone to be stung with nematocysts and usually chose smaller, less harmful anemones.
Closer examination shows a more distinct association between nematocyst batteries and the FMRF-IR network, similar to that found in tentacles by Anderson et al.
Given their location, these sensory cells could potentially serve a varied assortment of sensory functions given the important role of the tentacles in feeding and defense (including nematocyst discharge) and in stabilizing the bell while swimming (Shorten et al.
2003), and morphology of the nematocyst capsule provides the only morphological evidence for monophyly of the hexacorallian order Actiniaria (Reft and Daly, 2012).
Phyilosomas may be capable of defending themselves against any types of nematocyst sting, and it is likely that they have evolved to utilize venomous jellyfish as a food in the open sea, where food may be scarce.