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Molluscs Dorsal (back) Near hinge Oldest portion Anterior (Front) Posterior (back) Ventral (front) http://www.biologyjunction.com/clam_dissection.htm Mantle - tissue that lines both valves & covers the soft body of the clam. Points toward Anterior end Remove gills (and foot) to find visceral mass Nematodes = roundworms • have an alimentary canal (G.I. Tract) , lack circulatory system Platyhelminthes = Flat Annelids = ringed = segmented Nematodes = Round Tichruis trichiura = Whip worm Nematode: Trichinella spiralis Parasite in cyst How to identify Later you will recognize muscle tissue All mammalian tissue is fairly uniform with tissue transitions that are fairly defined / complete so the cyst looks pretty aberrant (unusual) Embryo inside Athropod – Crayfish sexing Morphology of a crayfish: edible freshwater crustacean, with pincers on the two forelegs. Claw: ends of the largest of a crayfish limbs. Rostrum: extension of a crayfish's shell. Head: foremost part of a crayfish. Thorax: upper part of a crayfish's body. Abdomen: lower part of a crayfish's body. Exopodite: external part of the uropod. Endopodite: internal part of the uropod. Uropod: swimming appendage of the crayfish. Telson: last segment of the abdomen of a crayfish. Segment: ring of the abdomen of a crayfish. Walking leg: limb of a crayfish used for forward motion. Coumpond eye (stalked eye): complex sight organ of a crayfish. Antennule: small antenna. Cheliped: front leg which ends in pincers. Antenna: organ of touch of a crayfish. Sexing Double = female Spiracle Starfish young Note Radial symmetry Canals are visible showing the water vascular system aboral oral Chordate Nerve cord and notochord Gill slits Post-anal tail Subphylum includes vertebrates = spinal cord So all vertebrates are chordates, but not all chordates are vertebrates However, vertebrates are the vast majority of chordates, only a few exceptions Chick 48hrs Chick 48hrs Chordate: Amphioxus (lancelet) A notable exception, invertebrate = no spine Does NOT have a skeleton surrounding nerve cord Immature Lancelet Nerve cord and notochord Post-anal tail Anus Gill slits The notochord is a flexible rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. Chordate: Tunicate (sea tulip) Another notable exception, invertebrate = no spine Does NOT have a skeleton surrounding nerve cord Does have segmentation but not a worm So likely a chordate
