what organs are used in the digestive track of cnidarians?
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The mouth, located at the center of one end of the body, opens into a gastrovascular cavity, which is used for digestion and distribution of food; an anus is lacking.\nAn evolutionary advance the Cnidarians have over sponges is extracellular \ndigestion of food. What this means is Cnidarians actually have a special \ngut cavity for digestion of captured food, rather than allowing each cell \nto do it, like a sponge does. All animals from Cnidarians up have kept \nthis feature! It's very important and allows the animal to be much more \nefficient.\n\nCnidarians (and Hydra) have a gut cavity with only a single opening. \nDigestive enzymes are released from the gut wall and help in the break-\ndown of the food. Once the food has been broken up into smaller particles, \ncells from the gut wall start engulfing the bits using the \nprocess "phagocytosis" (the same way an amoeba feeds).\n\nThe incredible thing about Cnidarian digestion is that when they arose, \nthey were the first animal ever to be able to eat and successfully digest \na piece of food LARGER that itself (although only small pieces by small \npieces).
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gastro intestinal tract
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Normally, it is considered to be Invertebrates the following taxa, though they do not include Hemichordata and Cephalochordata (Which are chordates but not vertebrates):\n\n- Protozoa: unicellular organisms\n- Porifera: sponges\n- Placozoa\n- Orthonectida: (Prev. Mesozoa)\n- Dicyemida: (Prev. Mesozoa)\n- Cnidaria: jellyfish\n- Ctenophora\n- Platyhelmintes: flatworms\n- Nemertea (= Rhynchocoela)\n- Gnathostomulida\n- Rotifera\n- Acanthocephala\n- Micrognathozoa\n- Gastrotrichia\n- Nematoda\n- Nematomorpha\n- Priapula\n- Kinorhyncha (= Echinodera)\n- Loricifera\n- Arthropoda: insects, spiders, crustacea, etc.\n- Annelida\n- Pogonophora\n- Vestimentifera\n- Echiura\n- Sipuncula\n- Mollusca\n- Phorona\n- Ectoprocta (=Bryozoa)\n- Brachiopoda\n- Entoprocta\n- Cycliophora\n- Echinodermata: sea stars, etc.\n\nYou can also include to de list Hemichordata and Cephalochordata.
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All animals move at some point in their life.  However, animals like sponges, hydras, anemones and coral are stationary in their adult form.
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they are called suckers on the ends of the tube feet.  they are controlled by the water-vascular system in echinoderms, such as starfish.  \n\ngood luck with the dissection!  i did it a few weeks ago...make sure to check out the two stomachs!!
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94. Annelida\n95. Echinodermata\n96. Mollusca\n97. Arthropoda
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1. Porifera (sponges), Cnidaria (jellyfish, coral polyps etc.), Ctenophora (comb-jellies), Placozoa (Trichoplax)\nIf we are speaking only about animals with distinct tissues, we must exclude Porifera.\n\n2. Mesoderm gives rise to muscle, connective tissue and circulatory system. So there are no specialized muscle cells (only "skin-muscle" cells) and no circulatory system in those animals. There are other parts that will be missing from those animals but not due to the lack of mesoderm - e.g., organ systems as such (even flatworms have defined digestive and excretory systems, for example).
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Jellyfish are marine invertebrates belonging to the Scyphozoan class, and in turn the phylum Cnidaria. The body of an adult jellyfish is composed of a bell-shaped, jellylike substance enclosing its internal structure, from which the creature's tentacles suspend. Each tentacle is covered with stinging cells (cnidocytes) that can sting or kill other animals: most jellyfish use them to secure prey or as a defense mechanism. Others, such as Rhizostomae, do not have tentacles at all. To compensate for its lack of basic sensory organs and a brain, the jellyfish exploits its nervous system and rhopalia to perceive stimuli, such as light or odor, and orchestrate expedient responses. In its adult form, it is composed of 94–98% water and can be found in every ocean in the world.\n\nMost jellyfish are passive drifters that feed on small fish and zooplankton that become caught in their tentacles. Jellyfish have an incomplete digestive system, meaning that the same orifice is used for both food intake and waste expulsion. They are made up of a layer of epidermis, gastrodermis, and a thick jellylike layer called mesoglea that separates the epidermis from the gastrodermis.\n\nTheir shape is not hydrodynamic, which makes them slow swimmers. But speed and low water resistance are not important as they are drifters that feed on plankton. It is more important for them that their movements create a current where the water (which contains their food) is being forced within reach of their tentacles. They accomplish this by having a body shaped like a bell which is rhythmically opened and closed.
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Kingdom: Animalia\nPhylum: Cnidaria\nClass: Scyphozoa\n\nThis is true for all jellyfish. After that they split up into several Orders:\n\nStauromedusae\nCoronatae\nSemaeostomeae\nRhizostomae\n\nHope I helped.
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Presence of Mitochondria\nCilia or Flagella used for cellular locomotion\nPresence of RNA
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Richard Dawkins has two wonderful chapters on cnidarians (jellyfish) and poriferans (sponges) in 'The Ancestor's Tale.'\n\nCnidarians have two body plans, the medusa (jellyfish) and the polyp (sea anemones and hydras).  Polyps often reproduce by budding and can make huge colonies of organisms.  The portuguese-man-of-war is actually a complex colony of medusa and polyp forms.  (BTW, he has a great discussion about how the stinger cell in jellyfish may be the most complex structure in any cell anywhere in the animal and plant kingdoms. Way cool!)\n\nPoriferans (sponges) are even simpler organisms.  Although they are ostensibly multicellular organisms, with several types of cells, these cells don't organize themselves into specialized tissues and organs. Sponges are able to reproduce both asexually and sexually.\n\nSo the evolutionary significance is that an individual is basically a colony.  As such they are right at the boundary between single-celled and multi-celled creatures.  They demonstrate how multi-celled organisms could arise as a colony of cooperating single-cells.
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Molluscs have an organ known as a mantle. It is the body wall covering beneath the shell. The outer layer of this organ secretes calcium carbonate using calcium from its blood. They can also secrete some proteins which give the shells colors and patterns while the mollusc is living. The inner layer of the shell is composed of nacre, which is a composite of calcium carbonate and organic materials. This is the material that makes the inner part of the shell iridescent, and the coating that makes pearls.
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A hydra does not have a bloodstream to distribute  nutrients. Food is moved directly from one cell to another from an inner cell layer that lines the interior cavity to an outer cell layer that covers the hydra.
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echinoderms, chordates, hemichordates, protostomes, Ecdysozoa \nLophotrochozoa \nPlatyzoa
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Hermatypic corals (the ones that form coral reefs) have symbiotic zooxanthellae (unicellular algae) within their tissues; the algae receive protection and housing from the polyps, and enable them to produce their calcareous exoskeleton.\nThere are sea anemones that attach to the dorsum of crabs, marine snails, etc. Thus the anemone "travels free" and the other animal is protected. \nMany species of small fishes and crustaceans shelter beneath the umbella of some jellyfish (read example at the link).
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Corals (class Anthozoa), which include sea anemones (order Actiniaria), are gastrovascular marine cnidarians (phylum Cnidaria) existing as small sea anemone-like polyps, typically forming colonies of many individuals. The group includes the important reef builders known as hermatypic corals, found in tropical oceans, and belonging to the subclass Zoantharia of order Scleractinia (formerly Madreporaria). The latter are also known as stony corals in as much as the living tissue thinly covers a skeleton composed of calcium carbonate. A coral "head" is formed of many individual polyps, each polyp only a few millimeters in diameter. The colony of polyps function essentially as a single organism by sharing nutrients via a well developed gastrovascular network, and the polyps are clones, each having the same genetic structure. Each polyp generation grows on the skeletal remains of previous generations, forming a structure that has a shape characteristic of the species, but subject to environmental influences.\n\nAlthough sea anemones can catch fish and other prey items and corals can catch plankton, they obtain much of their nutrient requirement from symbiotic unicellular dinoflagellates (type of algae) called zooxanthellae. Consequently, they are dependent upon growing in sunlight and for that reason usually found not far beneath the surface, although in clear waters corals can grow at depths of 60 m (200 ft). Other corals, notably the cold-water genus Lophelia, do not have associated algae, and can live in much deeper water, with recent finds as deep as 3000 m. Corals breed by spawning, with many corals of the same species in a region releasing gametes simultaneously over a period of one to several nights around a full moon.\n\nCorals are major contributors to the physical structure of coral reefs that develop only in tropical and subtropical waters. Some corals exist in cold waters, such as off the coast of Norway (north to at least 69° 14.24' N) and the Darwin Mounds off western Scotland. The most extensive development of extant coral reef is the Great Barrier Reef off the coast of Queensland, Australia. Indonesia is home to 581 of the world's 793 known coral reef-building coral species.\n\n\n\nHydra is a genus of simple, fresh-water animals possessing radial symmetry. Hydras are predatory animals belonging to the phylum Cnidaria and the class Hydrozoa.\n\nHydras are low power microscopical life forms and are often studied by biologists due to their regenerative powers. They can be found in most un-polluted freshwater ponds, lakes and streams in the temperate and tropical regions by gently sweeping a collecting net through weedy areas.
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algal production is the major source of energy for the anemone,  but they also hunt for food.  They are capable of travelling accross the reef on their 'foot'. they appear to have indefinate lifespans.  http://www.reefs.org/library/article/r_toonen8.html \nhttp://www.reefs.org/library/talklog/r_talukdar_102697.html