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 ?
The stickiness is caused by tiny stinging cells called nematocysts (NEM-uh-tuh-sists) lining the sides of the tentacles.
Slinging nematocysts within the anemone tentacles contain the venom beta phospholipase A2 and are used to stun prey or defend against potential predators (Grotendorst & Hessinger 2000).
Despite popular belief, chemicals such as alcohol, meat tenderiser, ammonia or baking soda should not be applied, as they only encourage more discharge by the nematocysts.
Most neomenioids are predators on octocorals or hydroids, whose nematocysts are seen in their midguts.
So far, every species of jellyfish against which Safe Sea has been tested has shown at least 90% inhibition of discharge of nematocysts, the tiny barbed venom-filled dartlike organelles that carry a skin striking force of 2-5 PSI.
This environment also has coral and creatures that can inject venom into a wound by means of nematocysts (stinging capsules) along with some nasty bacteria.
Presence of jellyfish or other jellies were identified by presence of tentacles, nematocysts, and whole or partial individuals.
The shell collector was thinking, just then, of the persistence of nematocysts.
Welcome to the world of cnidarians--a family of sea anemones, jellyfish and other marine invertebrates that kill their enemies and prey by firing poisonous, microscopic projectiles called nematocysts.
The tentacles contain nematocysts, a group of nasty little cells that can eject a toxin-carrying harpoon in a fraction of a second.
A sea anemone eats prey that it catches with its stinging nematocysts, which paralyze prey.