Phylum Mollusca Gastropods (Snails, slugs) Bivalves (oysters, clams, mussels) Cephalopods (squid, cuttlefish, octopus) Marine, freshwater, moist land Secretes shell Locomotive foot

Class Gastropoda Mantle –Tissue that secretes shell Radula –Rows of rasping teeth for grazing –Modified in predators

Cone shells Single harpoon tooth –evolved from rowed ancestors –filled with paralyzing venom Conotoxins –Medical value for specific neural & muscle treatment –Addictive-free pain killers

Class Bivalvia Clams, oysters, mussels… Suspension filter feeders –Incurrent & excurrent siphons Spade-foot for locomotion Two valves (shells) secreted by mantle –Held closed by powerful adductor muscles

Class Polyplacophora –Chitons Graze on microalgae 8 overlapping plates Class Scaphopoda –Tusk shells Open at both ends Deeper benthic sand/mud

Class Cephalopoda Squid, octopus, cuttlefish, nautilus Shell: internal, external, or lacking Well developed nervous system Most adapted for active predatory lifestyle

Muscular foot modified to arms &/or tentacles –Siphon for locomotion Hydropropulsion Ink sac or gland –defense Chromatophores –Adjustable pigment cells Conotoxins in some

Phylum Arthropoda Insects, spiders, crabs, shrimp, centipedes Aquatic and land External skeleton Jointed bilateral appendages Segmented body Open circulatory system Many marine crustaceans –Two pairs of antennae –gills

Class Copepoda Very abundant plankton Long first antennae

Class Cirripedia Suspension feeders –Cirri Protected by calcareous plates Free-swimming larvae

Decapoda Shrimps, crabs, lobsters… 5 pairs walking legs –Thoracic pereopods –1 st pr as cheliped 5 pairs abdominal appendages –Pleopods or swimmerets

Amphipoda & Isopoda Laterally flattened Shrimp-like Dorsal-ventrally flattened

Phylum Echinodermata Spiny skin 5 classes –Crinoidea--feather stars and sea lilies –Asteriodea--sea stars –Ophiuroidea--brittle stars and basket stars –Echinoidea--sand dollars and sea urchins –Holothuroidea--sea cucumbers All marine; mostly benthic (sea floor) Radial symmetry Water vascular system –Tube feet Some regenerate asexually

Lophophorates Lophophore = unique ciliated feeding structure Bryozoans –Colonial moss animals –Secrete CaCO3 Brachiopods –Two valves (shells) Chaetognaths –Lophophore modified –Voracious predators

Phylum Chordata Notochord –Flexible rod-like structure Dorsal nerve cord –Tube for nerves Pharyngeal gill slits –Respiration and feeding Post-anal tail –Reabsorbed in some species Invertebrate chordates examples –Urochordata Tunicates, sea squirts, ascidians –Cephalochordata lancelets