Phylum Mollusca Scheme of Shells and Tentacles General Zoology BIO 120 Lecture NOVA Loudoun Campus Fall 2013 BIO 120 Objectives 11 Chapter 11 Objectives Please respond to the following questions in preparation for the lecture evaluation on this material 1 To which phylum do molluscs belong What does mollusc mean Approximately how many species of molluscs are there 2 What are the five major classes of Mullosca and what sorts of organisms are included in each NOTE students should be familiar with Gastropoda Bivalvia Cephalopoda Polyplacophora and Scaphopoda 3 What are six general characteristics of molluscs NOTE students should refer to pp 232 233 Where do molluscs live What type of symmetry do they possess How many germ or tissue layers do they possess and what are they called What type of gut do they possess Do they possess a coelom Are molluscs protostomes or deuterostomes Do they possess a head What are the foot mantle siphon visceral mass mantle cavity and radula 4 What sort of circulatory system do they possess Do they possess respiratory systems 5 What are two general characteristics of gastropods and what are four representative members How many shells do they possess Where do they live and how many species are there What are torsion opercula and fouling 6 What are two general characteristics of bivalves and what are four representative members How many shells or valves do they possess Where do they live and how many species are there What are byssal threads 7 What are two general characteristics of cephalopods and what are four representative members How many shells do they possess How many arms and tentacles do squid and octopods possess Do octopods possess a radula or beak 8 What are two general characteristics of polyplacophorans How many interlocking plates do they possess Where do they live 9 What are two general characteristics of scaphopods How many shells do they possess Phylum Mollusca Scheme of Shells and Tentacles BIO 120 Objectives 11 1 Molluscs a Phylum mollusca b Mollusc soft c 100 000 living species 2 Classes of Mollusca a Gastropoda stomach foot i Snail slug nudibranch limpet conch b Bivalvia 2 shelled i Clam oyster mussel scallop c Cephalopoda head foot i Cuttlefish octopus squid nautilus d Polyplacophora 8 interlocking shells i Chiton e Scaphopoda Tusk shell 3 Characteristics of Molluscs a Coelom b Triploblastic i Muscle ii Cuticle iii Epidermis c Complete gut d Bilateral symmetry e Protostomes f Have head or reduced head g Foot muscular feature for movement h Mantle soft secretes shell protects visceral mass i Visceral mass internal organs j Siphon for feeding or respiration k Radula teeth like feature 4 Mollusc Body System a Open circulatory system except cephalopods i Ventricle ii Atria iii Blood vessels iv Respiratory pigments b Respiratory system 5 Gastropod a Characteristics i Have shell reduced shell or lacking ii iii Most diverse group Inhabits marine freshwater and terrestrial habitats Phylum Mollusca Scheme of Shells and Tentacles BIO 120 Objectives 11 b Members i Snail ii Slug iii Nudibranch iv Limpet v Conch c Torsion coiling of shell Fibonacci sequence d Opercula trapdoor to close shell e Fouling defecates on face due to torsion 6 Bivalve a Characteristics i 2 shells ii Mostly marine iii 30 000 species iv Reduced head v Most have siphon system vi Filter feeders vii Foot burrowing viii Byssal threads to attach to rocks ix Large gills x Abductor muscles b Members i Clam ii Oyster iii Mussel iv Scallop 7 Cephalopod a Characteristics i No or reduced shell ii Smart intelligent iii Tentacles and arms iv Lack radula have beak v Marine i Nautilus ii Cuttlefish iii Octopus 8 arms iv Squid 2 tentacles 8 arms b Members Phylum Mollusca Scheme of Shells and Tentacles 8 Polyplacophoran a Characteristics BIO 120 Objectives 11 i 8 interlocking shells ii Reduced head iii Radula iv Not very big v Movement by muscular foot vi Girdle vii Marine i 1 tusk shell ii Burrow iii Filter feed iv Opening on shell on both sides v Small vi b Scaphopod