BIOL 3454 1nd Edition Lecture 15 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 These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV V VI VII VIII IX X s gas is exchanged by gills lungs mantle or body wall t open circulatory system in all but closed in cephalopods 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 XI XII g Blood is always contained h Interstitial fluid bathes cells 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 similarly 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