BIOL 3454 1nd Edition Exam 4 Study Guide Lectures 15 20 10 17 Chapter 16 I II III Phylum Molluscs a 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 Mythology ii Cthulhu octopus face 1928 iii Bloop one of the 6 unexplained sounds from the ocean Phylogeny a Platyhelminthes is the out group b Conchifera contains monoplacophora gastopada ccephalopoda bivaliva and scaphopoda c Gastropoda and cephalopoda are sister groups d Bivalvia and scaphopoda are sister groups Mollusc characteristics a Very diverse b Dorsal body wall forms pair of folds mantle c 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 cleavage q Ancestral larvae trochophore r metanephridia 1 or 2 kidneys s gas is exchanged by gills lungs mantle or body wall t open circulatory system in all but closed in cephalopods IV V VI VII VIII IX X 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 Radula a Contains venum b Very diverse many shapes sizes c Some can stab Mulluscan foot a Locomotion or attachment b Also diverse c Slimy sliding surface for snails slugs d Muscular protuberance of bivalves e Attachment for limpets f Siphon of cephalopods Mantle a Mantle cavity houses respiratory organs b Gas exchange c 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 mantle shell a 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 life 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 cells e 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 expensive 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 expensive f 1 or more hearts pump blood into vessels that branch into small and smaller ones g Blood is always contained h Interstitial fluid bathes cells XI XII Digestive and NS a 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 gametes c 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 animal 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 water ii Floating fertilized egg iii Swimming straight hinge veliger iv Swimming late veliger v 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 20 I II III IV zebra mussels a first discovered in the US in 1988 from black and caspian seas b most likely introduced in ballast water c cuase a 40 million dollar impact in US yearly Class Caudofoveata a About 120 species of marine wormlike burrowing animals b Feed on microorganisms and detritus c Has an oral shield d Radula e Dioecious Class Solenogastres a About 250 species b Similar to caudofoveates c But no radula and no gills d Foot is a pedal groove e Hermaphroditic f Usually feed on cnidarians Class Polyplacophora a Chitons sea beaf b 7 or 8 articulated plates V VI c Sensory organs reduced esthestes eyes a photosensitive structure d Live on rocky surfaces in intertidal regions e 3 chambered heart f Can roll up like an armadillo g Clings with a broad foot h Most scrape algae i Some predatory j Pair of osphradia for chemoreception in mantle cavity k Sexes separate l Trochophores become juveniles no veliger stage Class Monoplacophora a Long thought to be extinct b About 25 species c Rounded shell d 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 Class Gastropoda a Most diverse 70 000 species b So big no single term snail slugs limpets conchs whelks periwinkles c Shells are the chief defense called a valve or univalve d Dextral right sinistral left dextral more common and is genetically controlled e 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 shell v Not a u shaped gut but through torsion have made it out the same shell opening g Torsion weirdness i Detorsion occurs in opistobranchs and pulmonates but derive from torted ancestors ii Torsion creates a problem anus opens over head and gills h Coiling i Not