BIOL 3454 1nd EditionExam # 4 Study Guide Lectures: 15-2010/17Chapter 16:I. Phylum Molluscsa. Molluscus = soft b. Coelomate c. Very diverse with about 90,000 species living d. Great fossil record e. Amazing morphological and behavioral diversity f. Very important to humans (food and industrially)g. Shallow marine h. Cuttle fish is intelligent and has image forming eyes i. Misc info i. The Kraken – Norse Mythologyii. Cthulhu – octopus face 1928iii. Bloop – one of the 6 unexplained sounds from the ocean II. Phylogeny a. Platyhelminthes is the out group b. Conchifera contains – monoplacophora, gastopada, ccephalopoda, bivaliva and scaphopodac. Gastropoda and cephalopoda are sister groups d. Bivalvia and scaphopoda are sister groups III. Mollusc characteristicsa. Very diverseb. Dorsal body wall forms pair of folds – mantlec. The mantle can be modified to form gills or lungs, secretes shell d. Ventral body wall sometimes a foot e. Radula in mouth and is very modifiable f. Can live everywhere g. Occastionally parasitic h. Bilaterally symmetrical and unsegmented i. Triploblastic j. All kinds of muscles – circular, diagonal and longitudinal k. NS with many large ganglia l. Sometimes a well developed brain (cephalopods have thinking brains)m. Highly developed sense organs (cephalopods have highly developed direct eye)n. Always sexual reproduction o. Monoecious and dioecious forms p. Spiral cleavageq. Ancestral larvae – trochophorer. metanephridia – 1 or 2 kidneyss. gas is exchanged by gills, lungs, mantle or body wallt. open circulatory system in all but closed in cephalopodsIV. Form and function a. Head/foot and visceral mass (some organisms emphasize one region other the other)b. Most have a radula – rasping, protrusible and tongue-like organ (can have us many as 250,000 teeth – new rolls continually replace old)V. Radula a. Contains venum b. Very diverse many shapes sizes c. Some can stab VI. Mulluscan foot a. Locomotion or attachment b. Also diverse c. Slimy sliding surface for snails/slugsd. Muscular protuberance of bivalves e. Attachment for limpetsf. Siphon of cephalopodsVII. Mantlea. Mantle cavity houses respiratory organs b. Gas exchangec. Ctenidia (gills in molluscs) exchanges oxygen and carbon dioxide between respiratory system and water or air (these run in opposite directions)d. Many taxa can withdraw head into mantleVIII. shella. secreted and lined by mantle b. 3 layers i. Periostracum – outer layer ii. Prismatic layer – middle layer of Calcium carbonate iii. Nacreous layer – inner layer continuously secreted by mantle and thicken through lifeIX. Open circulatory system a. Blood bathes the organs directly b. Insects, anthropods and most mollusks c. 1 or more heart pumps hemolymph through circulatory vessels into interconnected sinuses d. In sinuses hemolymph exchanges with body cellse. Relaxation of heart draws hemolymph back in through pores (valves)f. Sinuses are squeezed by body movement to help circulate g. Don’t need to be very efficient h. Less expensiveX. Closed circulatory system a. Bloods is confined to vessels b. Blood is separate from the interstitial fluid c. Annelids cephalopods and vertebrates d. More efficient at transporting e. More expensivef. 1 or more hearts pump blood into vessels that branch into small and smaller ones g. Blood is always contained h. Interstitial fluid bathes cellsXI. Digestive and NSa. Digestive system complex and highly specialized (lots of dietary diversity)b. Usually 2 kidneys – metanephridia i. Inner end opens into the coelom at a nephrostome ii. Kidneys sometimes release gametesc. NS usually similar than annelids or arthropods i. Cephalopods are the exception – have large well developed brains ii. Octopus brain – 2 big lobes are OPT (optical) 1. Sensory info and processing info from optic 2. Eye movement 3. Very visual animalXII. Reproduction a. Trochophore – larvae (similary to annelids and sometimes in egg)b. Direct metamorphosis c. Some have unique larvae stage – veliger d. Cephalopods have direct development e. Oyster life cycle – approximately 2 weeks i. Egg & sperm in waterii. Floating fertilized eggiii. Swimming straight hinge veligeriv. Swimming late veligerv. Swimming & crawling pediveliger (foot sits and crawls to good location) vi. Attach to oyster shell or hard surface vii. 1-3 yrs adult male and female 10/20I. zebra musselsa. first discovered in the US in 1988 from black and caspian seasb. most likely introduced in ballast waterc. cuase a 40 million dollar impact in US yearlyII. Class Caudofoveataa. About 120 species of marine wormlike burrowing animalsb. Feed on microorganisms and detritus c. Has an oral shield d. Radulae. Dioecious III. Class Solenogastres a. About 250 species b. Similar to caudofoveatesc. But no radula and no gillsd. Foot is a pedal groove e. Hermaphroditic f. Usually feed on cnidariansIV. Class Polyplacophoraa. Chitons – sea beaf b. 7 or 8 articulated platesc. Sensory organs reduced – esthestes (eyes) a photosensitive structured. Live on rocky surfaces in intertidal regions e. 3 chambered heart f. Can roll up like an armadillo g. Clings with a broad footh. Most scrape algae i. Some predatoryj. Pair of osphradia for chemoreception in mantle cavityk. Sexes separate l. Trochophores become juveniles (no veliger stage)V. Class Monoplacophoraa. Long thought to be extinct b. About 25 species c. Rounded shelld. Resemble limpets but have serially repeated organs (evidence of serial metamerism)e. Probably the sister group to polyplacophora (repeated structures probably ancestral to these two groups)VI. Class Gastropodaa. Most diverse 70,000 species b. So big no single term – snail, slugs, limpets, conchs, whelks, periwinklesc. Shells are the chief defense called a valve or univalved. Dextral (right)/sinistral (left) – dextral more common and is genetically controllede. Many have an operculum or cover that protects the shells aperture (opening)f. Gastropod form and function i. Exhibit torsion to fit into shell – all of the body morphs and changes through twisting ii. Ontogenetic – changes with age (during or after the veliger stage)iii. 2 step process – foot retractor muscle contracts and pulls shell and viscera 90 degrees counterclockwise then digestive tract moves laterally and dorsally iv. Torsion functions – puts gills and mantle cavity up front, allows foot to be pulled in last for protection and puts anus and mouth on same side outside