digestive system of cnidarians?
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courtesy of Encarta Encyclopedia Online!\nThe phylum of Cnidarians, or Coelenterates, is a phylum within Kingdom Animalia and consists of hydras, jellyfish, sea anemones, and corals. This phylum consists of over 9000 species. All cnidarians are radially symmetrical, meaning that they have a central axis and are symmetrical all around it. Their level of complexity is right above that of sponges, among the Metazoa, or many cells animals. In all cnidarians, the mouth leads directly into the gastrovascular cavity, a digestive cavity. This cavity is filled with fluid, which services internal cells, provides body support, and helps maintain structure. There is no anus, and so excess food and waste products must exit through the mouth. As a result, the digestive system of cnidarians is considered incomplete. Another characteristic of cnidarians is that they all have two layers of living tissue. The first layer of living tissue is known as the dermis, and the second layer is know as the gastordermis. The dermis is the outer layer, and the gastordermis is the inner layer which forms the body cavity. A gelatinous layer called mesoglea separates these two layers. Also, in all cnidarians, nearly all functions are performed by individual tissues, not organs, despite the fact that a very small number of them do contain organs. Another characteristic of cnidarians is that they all have two layers of living tissue. The first layer of living tissue is known as the dermis, and the second layer is know as the gastordermis. The dermis is the outer layer, and the gastordermis is the inner layer which forms the body cavity. A gelatinous layer called mesoglea separates these two layers. Also, in all cnidarians, nearly all functions are performed by individual tissues, not organs, despite the fact that a very small number of them do contain organs.\n\nPhylum Cnidaria includes the following classes:\n\n-Class Schphozoa (The jellyfish, or jellies)\n-Class Hydrozoa (Diverse polyps, including hydras)\n-Class Cubozoa (A minor tropical class with cuboidal swimming cups)\n-Class Anthozoa (Sea anemones, corals)
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Saliva; salivary glands; mastication; tongue; chyme; bolus; esophagus; peristalsis; smooth muscle; epiglottis; cardiac sphincter; stomach; fundus; hydrochloric acid; pepsin; pyloric sphincter; duodenum; bile; gall bladder; bile duct; pancreas; amylase; jejunum; absorption; mesentary; ileum; colon; apendix, cecum, rectum, anus.
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4. Please give me these answer for science.\nA. This is the largest animal in the world and a filter feeder.\n\n\n*** I think it is the Whale Shark, or some other type of whale (blue, basking, sperm...look up types of whales)****\n\n\nB. An animal whom lives in a animal or plant and takes food wihtout killing it.\n\n***Any type of parasitic worm...like hook worms or tape worms.  They live in the intestinal tract.****
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Sorry, I hate correcting people, but cnidarians aren't sponges.\n\nSponges are of the phylum porifera.\nCnidarians are things like coral and jellyfish.\n\nSponges have lots of holes.\n\nThey have loads of ostia, which are the small holes all around it, where water goes in to the sponge.\nDepending on the species, they may have 1 to 100s of osculums, which are the larger holes at the top where the water comes out.
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This lacks an actual question, but I see what your teacher is aiming at. \nHint: what is the main function of the large intestin? What is reabsorbed there that you wouldn't especially need in aquatic environments?
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Your digestive system.
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invertebrate\n\nmore info at\nhttp://www.ipm.ucdavis.edu/WATER/U/ceriodaph.html
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http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html
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Mollusks are triploblastic protostomes. The principal body cavity is a blood-filled hemocoel. It is unknown whether they have a true coelom (eucoelom); any coelomic cavities have been reduced to vestiges around the hearts, gonads, and metanephridia (kidney-like organs). The body is often divided into a head, with eyes or tentacles, a muscular foot and a visceral mass housing the organs.\n\nMollusks have a mantle, which is a fold of the outer skin lining the shell, and a muscular foot that is used for motion. Many mollusks have their mantle produce a calcium carbonate external shell and their gill extracts oxygen from the water and disposes waste. All species of the phylum Mollusca have a complete digestive tract that starts from the mouth to the anus. Many have a feeding structure, the radula, mostly composed of chitin. Radulae are diverse within the Mollusca, ranging from structures used to scrape algae off rocks, to the harpoon-like structures of cone snails. Cephalopods (squid, octopuses, cuttlefish) also possess a chitinous beak. Unlike the closely related annelids, mollusks lack body segmentation.\n\nDevelopment passes through one or two trochophore stages, one of which (the veliger) is unique to the group. These suggest a close relationship between the mollusks and various other protostomes, notably the Annelids.\n\nMollusk fossils are some of the best known and are found from the Cambrian onwards.
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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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The gastrointestinal tract or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and expels the remaining waste.\n\nThe GI tract differs substantially from animal to animal. For instance, some animals have multi-chambered stomachs.
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cephalochordates should be examined vis a vis Hemichordates and urochordates. According to older classification these are the the three sub phyla of the phylum chordata.\nThe salient features of cephalochordates is the notochord that extends up to the head region.In chordates the notochord gives rise to the vertebral column and hence it should not extend up to the head region as the first neck vertebra starts from the posterior part of the skull.\nOther important features of cephalochordates include the presence of circulatory system, excretory system formed by flame cells(protonephridia), presence of wheel organ, Hatschek' pits, ciliary mode of feeding, presence of atrial apertures, segmental musculature, presence of epipharyngeal groove and endostyle, ciliated pharynx. Ductless gonads.Two dorsal aortae.
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Not much. They don't have "guts" like more advanced animals. They do have specialized layers of cells that do different jobs. They have a thin layer of clear "skin" that has nerve cells underneath it, so they can sense prey and predators. They also have a hollow cavity with digestive cells (sort of like a very primitive stomach) inside them. They also have muscles that control their "hydrostatic skeleton" -- basically, another hole that fills up with water, and the muscles make to pulsate so they can swim.\n\nMost of a jellyfish is water. Water is what fills up the body and gives it shape. Outside the water, it's just a blob.
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They vary as widely as the body plans of different mollusks, but basically there are both macrophagous (herbivores and predators) and microphagous (suspension feeders) forms.\n \n**Gasteropods (snails and slugs) are mainly herbivorous; they use their radula to scratch plant tissues. However, there are also predatory snails (with modified radula, or proboscis, or even a venom-injecting radula). There are also microphagous planktonic forms (pteropods).\n**Cephalopods (squids, octopi and their relatives) are predatory carnivores, they have a modified radula and a horny "beak" with which they eat different invertebrates and vertebrates.\n**Bivalves (clams, mussels, oysters, etc) are primarily microphagous or suspension (filter) feeders. They don't have a radula and rely on their modified gills for filtration. There are also some primitive detritivores among the bivalvians.\n**The chitons (Polyplacophora) are grazing herbivores (with  radula).\n**The Scaphopoda (tusk shells) capture small food items (particulate matter) with their tentacles (captacula).\n**Other less known mollusks include the caudofoveatans (these capture foraminiferans and other very small organisms from sediments), solenogasters (these eat corals) and monoplacophorans (with a radula, but not much is known about their ecology).
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Sponges are Porifera; hydra are Cniderians.\n\nPorifera have body pores (ostia), canals and chambers that serve for passage of water. They also have choanocytes (collar cells) specialized cells that create water currents, as they are filter feeders.  \n\nCnidarians have stinging cells organelles called nematocytes or cnidocytes. They also have a nerve net with symmettrical and asymmetrical synapses.  They have a muscular system.
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Cnidarians live mainly in marine environments. Examples of cnidarians are the jellyfish, sea anemones, and corals. They are different from sponges because sponges have assymmetry which means they have no definite shape. Cnidarians have radial symmetry.
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Sea urchin belongs to a group of animals called: echinodermata (among them: starfish, brittle star and sea cucumbers). All echinoderms have a water-vascular system, a set of water-filled canals branching from a ring canal that encircles the gut. The canals lead to podia, or tube feet, which are sucker-like appendages that the echinoderm can use to move, grip the substrate, or manipulate objects. These tube feet are extended and retracted by hydraulic pressure in the water-vascular system. Pedicellaria are small, snapper-like skeletal elements that are used by the echinoderm to keep small organisms from settling on its body.