Phylum: Mollusca Class: Polyplacophora Class: Bivalvia Class: Gastropoda Class: Cephalopoda

Scallop Class: Bivalvia

Gastropod

Class: Polyplacophora Chiton Class: Polyplacophora

Cuttlefish Class: Cephalopod

Class: Gastropoda

Class: Bivalvia

Land slug Class: Gastropoda

Gastropod

Cephalopod

Nautilis Class: Cephalopoda

Class: Bivalvia Zebra Mussel

Food for thought

What Phylum have all of these animals been in?

GENERAL CHARACTERISTICS Lifestyle- Variety, bottom feeders, borers, burrowers, parasites, predators Economics- food, pearls, gardeners, hosts, sewers, predators, cleaning

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Bilateral symmetry Unsegmented, but has a definite head (cephalization) Locomotion- muscular foot Nervous system- Nerve cords, sensory nerve endings that sense touch, smell, taste, equilibrium, vision in some, and ganglia

body surface and gills or lungs Respiration- O2/CO2 exchange through body surface and gills or lungs Circulatory system Open system in most Closed system in cephalopods Digestion - complex and specialized in different molluscs - True coelom - Radula a hard tongue

Excretion- Specialized system with a pair of kidneys for osmoregulation Reproduction- Most are dioecious, some are hermaphroditic or monecious

Characteristics Class: Bivalvia two shells Examples Mussels Clams Scallops Oysters Shipworms

Bivalvia (continued) Filter feeders (*no radula*) No cephalization Reproduction- dioecious with external fertilization Development- 3 larval stages trochophore larva spat

Bivalvia Shells divided into two parts.  Gills are used for feeding and gas exchange. Example:  Clams, oysters

Spawning clam

Ex-current siphon

Incurrent siphon of giant clam

Bivalvia (continued) Respiration- gills in mantle Nervous system- 3 pair of ganglia with 2 pair of nerve cords Sense organs- chemoreceptors statocysts in foot (balance)

Characteristics Class: Gastropoda----Large foot Examples Snails Limpets Slugs Welks Conchs Sea slugs

Class: Gastropoda Largest and most diverse class of mollusca 2nd largest class overall 40,000 living species 15,000 fossils Most have shells most are bilateral/torsion causes asymmetry

Class: Gastropoda Mostly herbivours, some scavengers living on the dead and some carnivours Digestion- enzymes, extracellular and intracellular (chemical / mechanical) Respiration- By gills in the mantle Terrestrial has lungs

Class: Gastropoda Nervous system- 3 pairs of ganglia Reproduction- Dioecious Monecious, but self fertilization rarely occurs Sense organs- Tentacles on head which may have eyes Statocysts in foot

Characteristics Class: Cephalopoda Head foot Examples Squid Octopus Nautiluses Cuttlefish

Class: Cephalopoda Most complex class *Most advanced invertebrate brain* All are predators All are marine 2cm-30cm normal / Giant squid 18m Ink production for protection Chromatophores pigment cells in skin controlled by nervous system and hormones allow cephalopods to change colors

Class: Cephalopoda Locomotion-expelling water from mantle Reproduction- dioecious internal fertilization Circulatory system- Closed with capillaries to organs Respiration- Gills

Class: Cephalopoda Nervous system- Central with large brain Nerves with ganglia and buccal ring Sense organs Eyes Statocysts chemoreceptors

Cladogram phylum Mollusca Cephalopoda Bivalvia Gastropoda Polyplacophora Mollusca