I.I. AnnelidaAnnelida

A.A. PolychaetaPolychaeta• Larva = Larva = TrochophoreTrochophore

• Band of cilia around body; tuft on apexBand of cilia around body; tuft on apex• Same larval stage in Mollusca, Echiura, SipunculaSame larval stage in Mollusca, Echiura, Sipuncula

• Diverse lifestylesDiverse lifestyles• Free-living predatorsFree-living predators

• Often well-developed eyes and sense organs, jawsOften well-developed eyes and sense organs, jaws• Burrowing deposit feedersBurrowing deposit feeders• Burrowing suspension feedersBurrowing suspension feeders• Tube building suspension feedersTube building suspension feeders

• Tubes may be calcium carbonate, agglutinated or Tubes may be calcium carbonate, agglutinated or parchmentparchment

• SolitarySolitary• ColonialColonial

I.I. AnnelidaAnnelida

B.B. OligochaetaOligochaeta• Few marine speciesFew marine species• Small organismsSmall organisms• Benthic – mud and sandBenthic – mud and sand• Deposit feedersDeposit feeders• No parapodiaNo parapodia

C.C. Hirudinea (Leeches)Hirudinea (Leeches)• Few marine speciesFew marine species• ParasiticParasitic• No parapodiaNo parapodia

II.II. MolluscaMollusca

• More species (200,000+) than any other More species (200,000+) than any other animal phylum except Arthropodaanimal phylum except Arthropoda

• Soft bodySoft body• Unsegmented, typically bilaterally symmetricalUnsegmented, typically bilaterally symmetrical• Often protected by calcium carbonate shellOften protected by calcium carbonate shell• MantleMantle secretes shell secretes shell• Ventral muscular Ventral muscular footfoot• Many with head bearing eyes, sensory organsMany with head bearing eyes, sensory organs• RadulaRadula – Ribbon of small – Ribbon of small chitinchitin teeth used in teeth used in

feedingfeeding• GillsGills for gas exchange for gas exchange• Many permutations on basic planMany permutations on basic plan

• Bivalves lack radulasBivalves lack radulas• Squids have internal shellsSquids have internal shells• Octopuses have no shellsOctopuses have no shells

Fig. 7.19

II.II. MolluscaMollusca

A.A. Gastropoda (Class)Gastropoda (Class)• Largest, most common, most diverse Largest, most common, most diverse

groupgroup• SnailsSnails• Limpets - TerritorialLimpets - Territorial• AbalonesAbalones• NudibranchsNudibranchs – Some store elements of diet – Some store elements of diet

• Shell often coiled (Shell often coiled (Exceptions Exceptions ??))• Ventral creeping footVentral creeping foot• DietDiet

• Many vegetarian (scrape algae off rocks with Many vegetarian (scrape algae off rocks with radula)radula)

• Some predatorySome predatory• Prey on bivalves, worms, fishes, spongesPrey on bivalves, worms, fishes, sponges

Nudibranchs withsymbiotic algae

Fig. 7.20

Glaucus atlanticus

II.II. MolluscaMollusca

B.B. BivalviaBivalvia• Laterally compressedLaterally compressed• Two-valved shellTwo-valved shell• No headNo head• No radulaNo radula• Some have muscular foot for burrowing (Some have muscular foot for burrowing (How?How?))• Gills used for suspension feeding (active) & Gills used for suspension feeding (active) &

respirationrespiration• Water enters and leaves through Water enters and leaves through siphonssiphons

• Some anchor to substrate with Some anchor to substrate with byssal threadsbyssal threads• Largest mollusk (giant clam)Largest mollusk (giant clam)• Shipworms (boring – use shells as rasps)Shipworms (boring – use shells as rasps)• Common Common fouling organismsfouling organisms• Oysters – Produce pearlsOysters – Produce pearls• Scallops – Swim!Scallops – Swim!

Fig. 7.22

II.II. MolluscaMollusca

B.B. BivalviaBivalvia• Laterally compressedLaterally compressed• Two-valved shellTwo-valved shell• No headNo head• No radulaNo radula• Some have muscular foot for burrowing (Some have muscular foot for burrowing (How?How?))• Gills used for suspension feeding (active) & Gills used for suspension feeding (active) &

respirationrespiration• Water enters and leaves through Water enters and leaves through siphonssiphons

• Some anchor to substrate with Some anchor to substrate with byssal threadsbyssal threads• Largest mollusk (giant clam – Largest mollusk (giant clam – Tridacna gigasTridacna gigas))• Shipworms (boring – use shells as rasps)Shipworms (boring – use shells as rasps)• Common Common fouling organismsfouling organisms• Oysters – Produce pearlsOysters – Produce pearls• Scallops – Swim!Scallops – Swim!

Tridacnagigas

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