Phylum

Mollusca(5 Classes) Policemen censor gals in scant bikinis!

Polyplacophora – Many plates on a foot

Cephalopoda – Head foot

Gastropoda – Stomach

Scaphopoda – Tusk shell

Bivalvia – Hatchet foot

foot

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 (of say 4/5 have lungs?) You just have to think of which live on land

Oldest part of a univalve shell? Bivalve?

Answers…maybe• Gastropods, Cephalopoda, Mono-, A- & Poly-

placophora• Scaphopoda & Bivalvia• Gastropods Opisthosobranchia (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

Chitons radula, 8 plates

Class Polyplacophora

MantleAnus Gills in

mantle cavity

Radula in mouth

Head

Class Cephalopoda - Octopuses, Squid, Nautilus,Cuttlefish…beak, pen, ink sac, chromatophores,jet propulsion……….dissection.

I see Spot very well

I swim faster than Spot

I make make spots all over me in order to hide!

My tentacles (2) & arms are derived from the Gastropod foot

Class Gastropoda - snails, conchs torsion/coiling, radula, operculum.

Subclass Prosobranchia –pointed shells!

Aquatic GILLS

Subclass Pulmonata – rounded shells!

Land snails and slugs LUNG

Dextral

Detorsion…

If it looks strange, chances are itssomething from Class Gastropoda

Subclass PulmonataSlug

Egg Sac

Nudibranch

Class Gastropoda

‘POP’

Subclass Prosobranchia- aquatic snails (“shells”)

Subclass Opisthobranchia-Marine

-Nudibranchs / Sea slugs / Sea hares

-mantle cavity & shell reduced or absent

Subclass Pulmonata-Terrestrial Slugs and terrestrial snails

Class Scaphopoda - “tusk shells”

Currency for Wampum Indians. Head in sand. Respire through mantle (no gills.) Captacula for feeding on foramniferans,

Class Bivalvia or Pelecypoda - clams, scallops etc.filter feeders, bivalved shells…… dissection

D

VAP

Name of oldest part?

Class Bivalvia or Pelecypoda - clams, scallops etc.filter feeders, bivalved shells…… dissection

D

VAP

Umbo

Path of water (O2)

Mouth

VentricleBulbus arteriosus

Heart

Foot

Gills

Mantle

Excurrent

& Incurrent siphons

Schematic Diagram of a Clam Dissection

Gills or ctenidium –

Each = 2 demibranchs

Anterior (Umbo)

Posterior (siphons)

Dorsal (hinge)

Ventral

Auricle

Visceral Mass

Area of gastric & /digestive glands

Adductor muscles