Cnidaria Anhang

Cnidaria shoot out harpoon-like stinging hairs called Nematocysts/stun prey by injection of toxins and thereby aid in the ease of capture.

have a single body cavity with digestive, excretory and respiratory function.

= fluorescent/symbiosis with single-celled green algae species.

All Cnidarians have cnidae or nematocysts, specialized stinging cells. They have a single body cavity that serves as stomach, lung, intestine, circulatory system, and everything else. There is one opening (the mouth) into this cavity, through which all water, food, and gametes pass in and out. It is surrounded by a few or many tentacles, finger-like or filamentous projections which are usually studded with nematocysts. They are active in capturing food and transferring it to the mouth, and may be used defensively, too.

Sea anemones are members of the Anthozoa class incl. hard and soft corals/live attached to firm objects, generally the sea floor, or embedded in its sediments. An anemone's mouth points generally away from the substratum, and is surrounded by relatively short tentacles. Unlike most other anthozoans, sea anemones lack skeletons of any sort and are solitary. Other anthozoans, such as corals, commonly exist as colonies, with many anemone-like individuals attached to one another. Each cylindrical individual is called a polyp. Members of the other three Cnidarian classes may exist as non-motile polyps or as free swimming medusae - like the jellyfish, which is simply an upside-down polyp lacking a skeleton, free to swim in the open sea, with somewhat lengthened tentacles.

Cnidarians are carnivores that stun their prey with stinging cells loaded with nematocysts. These stinging cells are activated through a simple neural net, and biologists are studying Cnidarians for insight into how the nervous system evolved.

These animals possess specialized structures with tentacles that contain a wide variety of toxins, which are used in the capture of prey, as well as for defense against predators. Among these toxins, the peptides that act by binding to the ionic channels (voltage-gated sodium channels), are the substances most extensively studied and characterized.

These toxic sea anemone peptides may act predominantly as cardiac stimulants or as neurotoxins according to the degree of affinity with the isoforms of cardiac or neuronal sodium channels. The pharmacological effects of some anemone peptides on the nervous system have also been studied.

Studies with some sea anemone toxins, like granulitoxin, the neurotoxic peptide from the sea anemone Bunodosoma granulifera have produced seizures in rats. The Stoichactis kenti cytolic toxin, kentin, has proved to have the effect of a central stimulant on mouse brain monoamines producing fighting behavior. However, still with respect to the pharmacological effects on the central nervous system, no electroencephalographic (EEG) studies have been conducted thus far using sea anemone peptides.

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