Phylum Mollusca Polyplacophora Gastropoda Bivalvia Scaphopoda Cephalopoda 1

Phylum Mollusca Polyplacophora Gastropoda Bivalvia Scaphopoda Cephalopoda 1 Phylum Mollusca

Molluscs l Have adapted to a wide variety of habitats – 2 Terrestrial, marine, benthic, and accomplished swimmers. Phylum Mollusca

The Molluscan Body Plan l The body plan is similar and distinct from all other phyla l The Mollusca body plan includes: – – – 3 A large muscular foot A radula Mantle and mantle cavity Usually a small head Soft unsegmented body A hard non-living calcareous shell Phylum Mollusca

The Foot 4 Phylum Mollusca

The Radula 5 l Radula l Some molluscs have a rod of digestive enzymes (crystalline style) in the stomach Phylum Mollusca

The Mantle l 6 The mantle is the body wall that enclose the body cavity Phylum Mollusca

The Mantle Cavity l Houses the viscera and comb-like molluscan gills – l 7 Ctenidia are respiratory in function and can collect food particles Mantle cavity also is the site for reproductive, excretory, and digestive systems Phylum Mollusca

Taxonomic Summary l Phylum Mollusca – – Class Polyplacophora Class Gastropoda l l – – – 8 Subclass Prosobranchia Subclass Opisthobranchia Class Bivalvia Class Scaphopoda Class Cephalopoda Phylum Mollusca

Class Polyplacophora l Defining characteristics – l 9 Shell forms as a series of 7 to 8 separate plates Chitons Phylum Mollusca

Chiton Lifestyles l 10 Found close to shore mainly in the intertidal where they live on hard substrates Phylum Mollusca

Chiton Anatomy 11 Phylum Mollusca

Ingestion and Digestion l l 12 Radula is used to scrape algae from the rocks Mouth is anterior and anus is posterior; linear digestive tract Phylum Mollusca

Reproduction l Reproduction – – Sexes are separate with fertilization occurring in the water column Trochophore larvae l Free swimming which settles and metamorphoses into an adult 13 Phylum Mollusca

Local Representative l Eastern Beaded Chiton (Chaetopleura apiculata) – 14 Occurs subtidally on old shells Phylum Mollusca