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Exploring the Diverse Classes of Mollusca: A Comprehensive Guide

Delve into the intriguing world of Mollusca, covering 5 classes and their unique characteristics. Learn about radula, torsion, mantle function, currency shells, and more. Discover the differences between filter feeders, land, and water dwellers. Unravel the mysteries of gastropods, cephalopods, polyplacophora, bivalvia, and scaphopoda.

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Exploring the Diverse Classes of Mollusca: A Comprehensive Guide

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  1. Phylum Mollusca (5 Classes) Policemen censor gals in scant bikinis! Polyplacophora – Many plates on a footCephalopoda – Head foot Gastropoda – Stomach Scaphopoda – Tusk shell Bivalvia – Hatchet foot foot

  2. Typical questions for Mollusca How many of these specimens posses a radula? Which ones are filter feeders? Which have undergone torsion? Detorsion? What is the function of the mantle? Name a class used for currency Which specimens lungs vs. gills? Just have think of which live on land vs. in water…… Oldest part of a univalve shell? Bivalve?

  3. Answers…maybe • Gastropods, Cephalopoda, Mono-, A- & Polyplacophora • Bivalvia (Scaphopoda….have a captacula) • Gastropods Opisthobranchia (sea hares & sea slugs) and the land slugs of the Pulmonata • Mantle secretes the shell • Scaphopoda • Pulmonata – their name gives this away • Apex for Univalve, Umbo for bivalve but often the terms are used interchangeably

  4. Anus Gills in mantle cavity Mantle Radula in mouth Head Chitons radula, 8 plates ClassPolyplacophora

  5. My tentacles (2) & arms are derived from the Gastropod foot ClassCephalopoda - Octopuses, Squid, Nautilus, Cuttlefish…beak, pen, ink sac, chromatophores, jet propulsion……….dissection.

  6. Subclass Prosobranchia Aquatic –marine. Generally they have thick pointed shells, with spines. Many have opercula. Apex Gastropoda WORDS TO KNOW: snails, conchs, torsion, coiling, radula, operculum & egg sac Subclass Pulmonata Aquatic –freshwater. Shells are thin, rounded, with no spines, and have no opercula.

  7. Subclass Pulmonata Slug Detorsion… If something looks strange, chances are…. …….it is something from Class Gastropoda (…or your roommate!) Subclass Opisthobranchia Nudibranch

  8. This is correct! Class Gastropoda ‘POP’ Sinistral Dextral • Subclass Prosobranchia • - Aquatic snails (“shells”) • - Have gills • Subclass Opisthobranchia • Marine • Have gills • - Nudibranchs / Sea slugs / Sea hares • Mantle cavity & shell reduced or absent • Subclass Pulmonata • Terrestrial Slugs and terrestrial snails • Have lungs

  9. ClassScaphopoda- “tusk shells” Currency for Wampum Indians. Head in sand. Respire through mantle (no gills.) Captacula for feeding on foramniferans

  10. Name of oldest part? D P A V ClaBivalviaor Pelecypoda- clams, scallops etc. filter feeders, bivalved shells…… dissection

  11. Umbo D P A V ClaBivalviaorPelecypoda- clams, scallops etc. filter feeders, bivalved shells…… dissection

  12. Path of water (O2) Dorsal (hinge) Heart Ventricle Auricle Bulbus arteriosus Anterior (Umbo) Adductor muscles Area of gastric & /digestive glands Gills Posterior (siphons) Mouth Visceral Mass Excurrent & Incurrent siphon – (hairs & papullae) Foot Gills or ctenidium – Each = 2 demibranchs Mantle Ventral Very Schematic Diag. of a Clam Dissection

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