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Phylum Mollusca Fig. 16.CO.

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Presentation on theme: "Phylum Mollusca Fig. 16.CO."— Presentation transcript:

1 Phylum Mollusca Fig. 16.CO

2 Phylum Mollusca Protostomes Lophotrochozoan group
Eucoelomates (coelomates) Tridacna gigas Tridacna squamosa

3 Phylum Mollusca Soft Bodied Shelled Cephalization Body Divisions
Some without Cephalization Sensory organs Mouths Body Divisions Visceral Mass Head-Foot Mantle Fig. 16.1a Tonicella lineata

4 Phylum Mollusca Complete digestive tract Digestive glands
Octopus briareus Complete digestive tract Digestive glands Specialized feeding structures Circulatory system Heart (2 chambers) Open system in most groups Closed in cephalopods Coelom restricted to pericardium in most cases

5 Phylum Mollusca Advanced nervous system Excretory system Reproduction
Brain Sensory organs Eyes (simple and camera) Sensory papillae Excretory system Kidney-like nephridia Reproduction Monoecious and dioecious External development External & internal fertilization

6 Mollusc Phylogeny Mantle secreting shell Muscular foot Chambered heart

7 Mollusc Taxonomy Polyplacophora Major classes Chitons
Chiton tuberculatus lives in the rocky intertidal zones eat algae with its radula 8 shell plates Major classes Polyplacophora Chitons

8 Mollusc Taxonomy Gastropoda Major classes Subclasses: Prosobranchia
Atlantic triton’s trumpet (Charonia variegata) Major classes Polyplacophora Gastropoda Subclasses: Prosobranchia Shelled marine gastropods Tiger cowrie (Cypraea tigris)

9 Mollusc Taxonomy Gastropoda Major classes Subclasses: Opisthobranchia
Spotted sea hare (Aplysia dactylomela) Major classes Polyplacophora Gastropoda Subclasses: Prosobranchia Opisthobranchia Sea slugs (marine) Phidiana hiltoni zebra sea goddess (Hypselodoris zebra)

10 Mollusc Taxonomy Gastropoda Major classes Subclasses: Pulmonata
Helminthoglypta walkeriana Major classes Polyplacophora Gastropoda Subclasses: Prosobranchia Opisthobranchia Pulmonata Terrestrial snails/slugs Freshwater snails Giant banana slug (Ariolimax columbians)

11 Mollusc Taxonomy Bivalvia Major classes Polyplacophora Gastropoda
Bay scallop (Aequipecten irradians) Major classes Polyplacophora Gastropoda Bivalvia Clams, oysters, mussels, scallops Edible mussels (Mytilus edulis) Ostrea edulis

12 Mollusc Taxonomy Major classes Cephalopoda Polyplacophora Gastropoda
Giant cuttlefish (Sepia latimanus) Major classes Polyplacophora Gastropoda Bivalvia Cephalopoda Octopus, squid, nautilus Octopus sp Nautilus sp

13 Generalized Mollusc Anatomy
Fig. 16.2

14 Gastropod Feeding Apparatus
Fig. 16.3

15 Respiration: Gills Fig. 16.4

16 Shell Structure & Formation
Fig. 16.5a

17 A Pearl Among the Swine Fig. 16.5b

18 Mollusc Reproduction & Development
Indirect development Larval stages Trochophore larva Free swimming, ciliated, shell formation begins Veliger larva Free swimming, ciliated velium forms, Shell/body torsion occurs Spat Metamorphic form between veliger and juvenile Shell elaborates

19 Trochophore Larva Fig. 16.6

20 Gastropod Veliger Larva
Mouth Velia Fig. 16.7 Shell


22 Veliger Zygote Trochophore Juvenile Spat Adult

23 Adult Abalone Fig a

24 Class Gastropoda The Shell Game Fig

25 Class Gastropoda - Torsion

26 Gastropod Shell Coiling

27 Generalized Gastropod Anatomy

28 Marine Gastropods Cowries Fig b

29 Marine Gastropods Sea Hare – Aplysia sp Fig

30 Marine Gastropods - Nudibranch

31 Terrestrial Gastropods - Pulmonata
The mantle cavity serves as a “lung” Glandular epidermis Secrete mucus (slime) upon which gastropod glides Fig a

32 Terrestrial Gastropod - Pulmonata
Pneumostome Fig b Slugs lack shells Mantle thickened Pneumostome Air intake into mantle cavity

33 Phylum Mollusca, Class Bilvalia
Two shells Incurrent & excurrent siphons No cephalization Fig

34 Generalized Bivalve Anatomy

35 Bivalve Anatomy (Sagittal)
Fig b

36 Bivalves are Typically Filter Feeders
Fig a

37 Bivalve Life Cycle Fig

38 Glochidia – Unique Larval Stage of Freshwater Bivalves
Internal fertilization Early development in brood chamber (region of mantle cavity) Release of glochidia veliger larvae Glochidia attach to gills of fish and are distributed Fig a

39 Phylum Mollusca, Class Cephalopoda
Closed circulatory system Shell: lost in Octopus, extremely reduced and enclosed in mantle in squid, planar spiral in Nautilus Cephalization eye Beak around mouth Tentacles/arms Fig

40 Cephalopod Anatomy Fig a

41 Squid are the largest Cephalopods

42 Cephalopod Eye Fig

43 Mating Fig

44 Direct Development in Cephalopods

45 Color & Morphology Changes for Camouflage

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