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This 4 page Class Notes was uploaded by Emma Cox on Thursday April 7, 2016. The Class Notes belongs to BIOL 1030 - 002 at Auburn University taught by Debbie R. Folkerts in Summer 2015. Since its upload, it has received 40 views. For similar materials see Organismal Biology in Biology at Auburn University.
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Date Created: 04/07/16
Acoelomate bilateria (cont.) o Phylum nemertea – proboscis worms, ribbon worms Rhynchocoel – cavity that houses the proboscis Proboscis Complete gut – have a mouth and anus; oneway traffic of food therefore areas of gut specialize for certain parts of digestion Free living True circulatory system Longest animal on earth is a member of this phylum Often very flat and very narrow to allow minimal distance across mesodermal tissue Marine and freshwater species – largest tend to be marine Lineus longissimus – bootlace worm (first to be collected 180 ft long) Prostoma graecense – local freshwater species. Hot dog shaped Proboscis just as long as the body Proboscis ejected from the body by turning inside out (eversion) – put pressure on fluid in the rhynochocoel cause the eversion Barb at functional end of proboscis allow them to harpoon prey Retractor muscles – able to extend and contract to a greater degree than any other kind of muscle – at fullest length they are 30x their retracted length Eumetazoa o Bilaeria Protostome Lophotrochozoa Phylum Mollusca o Visceral mass Thin body wall that contains all the viscera (contains organs) o Foot Have one foot Ventral Ancestral – flat creeping, sole like structure o Mantle Second body wall Enclose body and creates a cavity between mantle and body Secretes the shell o Shell Highly calcareous 3 layers o Radula Feeding structure Tonguelike structure a snail use to scrape algae off side of aquarium o Crystalline style Feeding structure Pull food downward into gut o Trochophore and veliger larval stage Veliger stage = second larval stage Look like a butterfly Develop a second body wall – mantle o Mantle Secretes shell Houses body and provides mantle cavity o Mollusc shell – 3 layers Periostracum – outer layer Differ in thickness and color depending on species Can wear off of old shells Ostricum means shell, peri means around = layer around outside of shell Considerable amount of protein in it that gives it color Calcium housed within meshwork of protein Ostricum (Pristmatic layer) Thickest layer calcareous Nacreous layer Smoothest layer What touches the soft body of the mollusk Nacre – makes it shiny and iridescent o Molluscan foot Ancestrally a ventral, creeping sole with rippling muscle action Muscle contraction move in wavelike fashion from anterior to posterior end to propel across a substrate Visceral mass contained within the coiled shell (snail) Coiled mantle = coiled visceral mass (for snail) Sometime hatchet shaped for burrowing (in clams) Sometime divided into arms (cephalopods) o Radula Protrusible, rasping, tonguelike structure, with chitinous teeth, used to rasp or graze periphyton Good for scraping algae or rasp a hole in prey (octopus) o Crystalline style – a proteinaceous, rotating rod in the gut of continuous feeders, used to twist and pull a mucus cord of food into the stomach Crystallized protein o Class Polyplacophora – chitons Divided shell (8 valves) and thick mantle allow tight grip on substrate\ Divisions make it flexible Animals attached to rock Feed on periphyton with radula Body well suited to hanging onto rocks like a suction cup o Class Gastropoda Snails, conchs, whelks, abalone, limpets, etc. Torsion during development Coiled shell Asymmetrical body Marine, freshwater, and terrestrial Mantle cavity houses gills or lungs Foot where belly should be (on ventral side) = large ventral foot = what gastropoda means During embryological development go through a process called torsion – twisting and coiling Start out as bilaterally symmetrical but end up very asymmetrical Prominent head with eyes on tentacles Gastropod spiral shell (conk) Protoconch – tiny shell they started with Whorls curling round and round – whorls combined make a spire Body whorl is the last and largest and most of the body is found within this Opening of body whorl is the aperture – differs among species Foot extends from aperture Operculum can cover the aperture Slugs Mantle = saddle on back of animal No shell Tentacles with eyes Pneumostome – breathing hole Lacks bilateral symmetry A trend of shell reduction in terrestrial slugs Marine slugs – nudibranchs and sea hares o Class Cephalopoda Squid, octopus, nautilus Foot divided into 8 arms or 8 arms and 2 tentacles “head foots” – cephalo and poda mantle forms the body tube squid – masters of colorchange 8 arms, 2 tentacles = decapods giant squid – largest of all invertebrates o live in very deep ocean = don’t know much about them vampire squid o live in deep water with no light whatsoever o red = invisible o almost no oxygen where they live o produce bioluminescence o eyespots can get smaller and smaller to make it look like they are swimming away chambered nautilus (nautilus) o only shelled members that still exist o can control amount of gas in their chambers = control buoyancy o Classs Bivalvia – largest class (along with Gastropodia) Clams, mussels, oysters, scallops, etc. 2part, hinged shell flexible periostracum makes the hinge mantle forms siphons ciliated gills accomplish water flow, respiration, filter feeding, etc. water move in and out of mantle cavity, bringing food in and waste out o also allows them to distribute gametes o also allows for respiratory gas exchange a line of symmetry runs between the valves razor clams incurrent and excurrent siphons – extend to surface of water allowing them to burrow down giant clam symbiotic algae live within the mantle tissue oysters sessile and have a reduced foot one valve is attached to a substrate pearls may form in the nacreous layer scallops swim by rapidly opening and closing their shell one large adductor muscle, eyes on mantle edge mussel marine mussels form a byssus – glue that works underwater byssal threads are the stuff of the mythical cloth of gold clams have a burrowing foot siphons may be very long
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