Explain the function of nematocysts.?

Answer 1

right.. so cnidarians have these structures known as cnidae which give the group it's name. Each cnidae is located within a specialized cell that houses it, this cell is a capsule with an attached hollow thread. Nematocyst is the more familiar term applied to specialized cnidae that are characteristic of scyphozoan and other types of jellies, and other cnidarians.

As to the functions: stinging nematocysts function primarily for the capture of prey, and secondarily as a defense mechanism. There are many types of nematocysts, such as those that function to inject toxins to immobilize prey, and those which serve to entangle and hold onto the intended meal by wrapping around it. Species of cnidarian jellies vary in the types of nematocysts they possess, and this can be used to some extent in classifying and identification.

Most nematocysts are located on the tentacles of the jelly, which are the primary food capturing part of the body, though they can also be found around the mouth and on the gastric filaments of the stomach.

Both mechanical and chemical stimuli may act to trigger nematocyst firing, but contact with members of their own species generally doesn't result in firing. Within a fraction of a second, hundreds or even thousands of nematocysts discharge with sufficient force to penetrate the skin or exoskeleton of the prey. They can discharge even after the jellyfish has been dead for hours or days.

Many jellyfish toxins have harmful effects on cell membranes and cause them to rupture; and this may lead to the breaking up of red blood cells. Other toxins have disruptive effects on the action of nerve and muscle cell membranes and impair their normal function. Some other toxins degrade collagen, break down proteins and lipids, and disrupt cellular influx of ions like calcium.

Answer 2

Cnidocytes, also known as cnidoblasts or nematocytes, are prey-capture and defensive cells unique to and present in all animals of the phylum Cnidaria
Cnidocytes are single cells, each containing a subcellular organelle called a cnidocyst. The cnidocysts are composed of a hollow coiled thread-like structure attached to the bulb-shaped nematocyst capsule body. The externally-oriented side of a cnidocyte cell also has a hair-like trigger on it, called the cnidocil. When the trigger is activated the cell "fires" - the shaft of the cnidocyst penetrates the target and the hollow thread is everted into the target organism body. This discharge is one of the fastest biological processes, takes no more than a few microseconds and reaches accelerations of about 40,000g[1]. Following penetration, the toxic content of the nematocyst is injected into the target organism. The rapid activity of the injected neurotoxins serves to immediately paralyze the mobile prey, thus allowing the sessile cnidarian to devour it.

Answer 3

i'm not sure of the spelling, but i think pneumatocysts are cells that have a special part of them that sting. this has two functions: to stun passing prey and for defense.