What is the function of the toothlike projections at the dorsal edge of the clam's valves?
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These projections interlock when the valves are closed, thus giving more protection to the animal. Also, an animal with these structures may keep their valves half-open, thus permitting water circulation but protecting the soft parts with this natural "portcullis". Some brachiopods (other marine valved animals) also have these type of morphology.
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Chordae Tendinae are Cord-like tendons that supports the Tricuspid Valve(right) and the Mitral Valve(left). They are connected to papillary muscles, which limit movements of those valves.
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Gastrovascular cavity, as the name indicates, functions in both digestion and the transport of nutrients to all parts of an animal body. Organisms belonging to two major phyla, the Cnidaria and the Platyhelminthes, possess gastrovascular cavities. The radially symmetrical cnidarians have a sac-like body in two distinct layers, with a jellylike layer between. Extracellular digestion takes place within the central cavity of the sac-like body. This cavity has only one opening to the outside and that is surrounded by tentacles in most cnidarians. The tentacles serve to capture prey.
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inside the mouth...usually in the gums closest to the tooth being filled
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They have mouth openings often with flagellum to help with their filter feeding.  The tail end is thinner and is lighter in color/more transparent.  Just do an image search for amphioxus and see!
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go to this link, you will find out where it is in the pic:\n\nhttp://www.coolnurse.com/anatomy.htm
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Question is a little vague......anatomy is structural and function is physiological, so I am not sure what your question really is; is it about anatomy or physiology or both? So RSVP:  Are you asking about the unique physiology or anatomy of amphibians?\n\nThey have many structures in common with the other tetrapod vertebrates, but also have unique structures as amphibians.  Plus each sub-class-type of amphibian (frogs-toads) vs (newts-salamanders) vs caecilians are each different.\n\nAll amphibians have their unique slimey scaleless skin through which they attain most of their oxygen and release their CO2 by diffusion, their 3-chambered heart with 2 atria and 1 ventricle, their external fertilization type reproductive system that has egg-larva-tadpole and adult.  Their respiratory system changes at each stage of development. As tadpoles they use their gills. As they metamorphose to adults,the gills are absorbed and lungs develop to breathe air although they lack a diaphragm and ribs (in most...some amphibians retain larval stage for their whole life...axolotyl). They have kidneys and bladder for excretory system; endoskeleton is bone and has most of the same bones as us, although some are fused (radio-ulna, fibulo-tibia; no skull protecting brain, unusual urostyle bone of pelvis.
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Crab's heart...\nA crab's heart is located dorsally in the center of the carapace and is suspended under the surface of the carapace by strands of connective tissue. It is single-chambered.\n\nWorm heart...\nEarthworms possess five hearts. The calciferous glands between the hearts manage excess calcium in the worm's diet, a problem you may have if you eat a lot of dirt.
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Wikipedia says that it is unknown whether mollusks  possess a eucoelom, they have a hemocoel to facilitate blood movement however.
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here's a link that i think would fully answer your question\nhttp://en.wikipedia.org/wiki/Odontoid_process\n\nhope it helps :)
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The digestive tract is complete and ciliated, with a mouth, anus and complex stomach. The pattern of the stomach varies according to the mollusks diet.  Food is taken up by cells lining the digestive glands arising from the stomach, and then is passed into the blood.  Undigested materials are compressed and packaged, then discharged through the anus into the mantle cavity and are carried away from the animals in the water currents.  This packaging of wastes in solid form prevents fouling of the water passing over the gills. \n        Excretory functions are carried out by a pair of nephridia, tubular structures that collect fluids from the coelom and exchange salts and other substances with body tissues as the fluid passes along the tubules for excretion. The nephridia empty into the mantle cavity.
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The clam shell is made of three layers, the horny outer layer (periostracum), the thick middle layer called the prismatic layer, and the innermost layer called the pearly layer (the nacreous layer)
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I would look here for your answer and/or a link that could get you your answer http://en.wikipedia.org/wiki/Vertebrate\n\nGood Luck!!!
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The Annelida have bilateral symmetry .The annelids also have a one-way digestive system . It has a segmented anterior with 8 hearts in each. It also has a body cavity. \n\nThe Mollusks are also bilateral like the annelids. They have a good nervous system. They also have a one-way digestive system. They have a coelom like the . The classes of mollusks are the bivalves, which have two valves, which the name suggests. It has 2 shells and 3 layers also. It has a mantle and it lives in the water. It has gills and abductor muscles. It has an excurrent and incurrent siphon, which no other phylum has. There are the gastropods, which live in land and ocean. It has one shell and one foot. There are also the cephalopods, which has tentacles a foot that can either be a sucker or hook.
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Mammalian ovum is round and that helps in its movement through the fallopian tube since it does not have a tail like the sperm.  But the ovum is not smooth over the surface due to layers of cells.  Read through and i think my answer will help u..................The zona striata or zona pellucida is a thick membrane, which persists for some time after fertilization has occurred, and may serve for protection during the earlier stages of segmentation.  The phenomena attending the discharge of the ova from the follicles belong more to the ordinary functions of the ovary.
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The hard, rigid outer covering of certain animals is called a shell. While many animals, particularly those that live in the sea, produce exoskeletons, usually only those of mollusks are considered to be shells. It is sometimes erroneously claimed that shells are made of chitin, but these are unrelated materials (except for their hardness and use as a covering by animals).\n\nThe shell is usually made of nacre, an organic mixture of outer layers of horny conchiolin (a scleroprotein), followed by an intermediate layer of calcite oraragonite, and then a layer of calcium carbonate (CaCO3) in the form of platy crystals.\n\nNacre is secreted by the epithelial cells (formed by the germ layer ectoderm) of the mantle tissue of certain species of mollusk. Mollusk blood is rich in a liquid form of calcium. In these mollusks the calcium is concentrated out from the blood where it can crystallize as calcium carbonate. The individual crystals of each layer differ in shape and orientation. Nacre is continually deposited onto the inner surface of the animal's shell (the iridescent nacreous layer also known as mother of pearl), both as a means to smoothen the shell itself and as a defense against parasitic organisms and damaging detritus.\n\n \nVarious seashellsWhen a mollusk is invaded by a parasite or is irritated by a foreign object that the animal cannot eject, a process known as encystation entombs the offending entity in successive, concentric layers of nacre. This process eventually forms what we call pearls and continues for as long as the mollusk lives.\n\nShells are very durable and outlast the otherwise soft-bodied animals that produce them by a very long time. Large amounts of shells may form sediment and become compressed into limestone. Shells that wash up on beaches are called seashells, and are collected by some enthusiasts
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<>Actually, this is not as easy as I thought it would be.  Here're a couple sites to look at.  I'll see if I can find more.\nPS: I guess it would be easier if you were to specify a particular bivalve.  There is a variety of articles on different ones here:\nhttp://www.student.loretto.org/zoology/Bivalve.html\nhttp://cars.er.usgs.gov/Region_5_Report/html/bivalves.html\nhttp://www.esg.montana.edu/dlg/aim/mollusca/bivalve.html\nhttp://www.chesapeakebay.net/info/hard_clam.cfm\nhttp://www.aquaticinvaders.org/nan_browse.cfm?level=4&key=030201000000\nhttp://www.aquaticinvaders.org/nan_browse.cfm?level=4&key=030201000000