Taxonomy Kingdom Animalia Phylum Mollusca Class Class Class Class Polyplacophora Gastropoda Bivalvia Cephalopoda (means bearing many plates) (means stomach/foot) (means 2 shelled) (means head/foot)

Phylum Molluscs Mollusc = soft body Examples: snails, slugs, octopus, clams, oysters, chiton

General The second largest phylum of animals (arthropods is the largest) Range from simple animals (clams) to very complex animals (octopus) Have a muscular foot for movement Have a mantle cavity which sometimes excretes a shell Have glands that secrete mucus Coelomates: have a true body cavity Live in the ocean, in freshwater or on land Most have a radula (toothed tongue) for scraping and chewing

Hawaiian Bobtail Squid

Blue Ringed Octopus

Giant Squid

Body Plan

Body Plan Foot: contains sensory organs and muscles for moving Visceral Mass: contains digestive, reproductive and circulatory organs Mantle Cavity: contains the lungs or gills and secretes the shell if there is one

Digestion Digestion: highly complex and specialized to each mollusc’s diet Radula: a toothed structure that extends out for scraping food snail eating

Circulation Circulation: open circulatory system with a heart and blood vessels

Nervous System Nervous System: several of ganglia (masses of nerve cells) and nerve cords

Respiration Respiration: gas exchange through either gills or lungs

Movement Movement: the foot is used for moving and is specialized in each mollusc clam moving

Reproduction Sexual: Dioecious – fertilization is internal or external and eggs are laid Asexual: hermaphrodites but do not fertilize their own eggs Or parthenogenesis cuttlefish mating

Ecological Relationship Food source for many animal, including humans Produce pearls (oysters) Some are invasive species (zebra mussels, snails, slugs) Venoms are used in neurological research

Class Polyplacophora Means “bearing many plates” Found on rocky surfaces Can roll up for protection Most ancient species Example: Chitons chitons

Chiton

Chiton

Chiton

Chiton