What is the difference between a nematocyst and a cnidocyte?

Answer 1

difference/s: Hydras live in fresh water environments, while sea anemones live in marine environments. Hydra, although primarily sessile (sedentary), may move up to several inches in a day.

similarities/s: both are part of the phylum cnidaria, have radial symmetry, a gastrovascualr cavity, an incomplete digestive system (only one opening, considered their mouth), a mouth surrounded by tentacles, and both are sessile polyps.

Answer 2

Cnidae (singular, cnida; from the Greek word for nettle) are types of cells that define an entire phylum of invertebrates, the cnidarians. All species in this phylum have specialized cells (cnidocytes) that contain a very complex and useful mechanism, the cnidocyst. There are three categories of cnidae- nematocytes (from the Greek word for thread), spirocytes, and ptychocytes. However, spirocytes and ptychocytes are restricted to a minority of the major cnidarian taxa.

Cnidarians are continually making new cnidocyte cells from stem cells, and the immature cells are known as cnidoblasts (or nematoblasts if the mature cell becomes a nematocyte). These specialized cells can serve many different purposes. They can tangle, anchor, glue, attach, or envenomate prey, predators, or their environment (usually substrates). Their functions include predation, defense, and mobility.

Nematocyte cells are made up of a nucleus, mitochondria, an outer wall, and a vesical (pocket) containing an organelle (sub-cellular organ) called a nematocyst. This nematocyst organelle consist of two outer walls, a cnidodil (trigger protrusion), operculum (hinged door), as well as the specialized apparatus within their sac to accomplish the various tasks mentioned above. They can contain tubes, spikes, darts, sticky bulbs, threads (actually tubules since they are hollow), harpoons, spiral entanglements, cutting barbs or any combination of these devices.

Nematocysts are usually triggered by a combination of mechanical stimulation of the cnidodil, chemical stimulation from adjacent sensor cells, and neuronal excitation and inhibition from a nerve ring network. This complexity of trigger control is necessitated by the cost of unproductive firing, since once triggered, the entire nematocyte is absorbed into the organism and a new cell must be produced near the base of the tentacle and traverse down the tentacle to replace the missing cell. The entire process of forming new nematocytes from stem cells, migrating to a final location, and incorporating into the ectoderm in a very precise pattern takes only about five or six hours.

The nematocyst (thread sac) is a non-living secretion of the nematocyte cell, like quills, feathers, or even our own hair. But within this tiny single cell lies one of the most amazingly complex mechanisms in the animal kingdom, ready to fire a harpoon at an acceleration of a million times that of gravity and inject deadly toxins all along its tubule in a period of about 3 msecs.

Answer 3

Nematocysts are on Cnidarians, spicules are in Poriferae

Answer 4

A cnidocyte is a type of venomous cell that is found in coelenterates. A nematocyst, meanwhile, is a specialized organelle found inside the nematocysts of coelenterates.

Answer 5

Sea anemones are plants that sting you when you touch them and hydras are a minute freshwater coelenterate with a stalklike tubular body and a ring of tentacles around the mouth.

Answer 6

the hydra stings on touch, the sea anemone stings the protective coating (slime) on all fish except clownfish, which is why they can live together.

Answer 7

Nematocysts are the stinging cells and are located inside of the cnidocytes