1. Phylum Mollusca

2. Includes these classes: Snails-class Gastropoda Clams-class Bivalvia Octopuses, Squids-class Cephalopoda There are more species of mollusks in the ocean than any other group Soft body protected by a shell of calcium carbonate Very diverse in body structures and habits

3. Mollusk Diversity

4. Biology Much more complex than Cnidarians or Sponges Has a separate mouth and anus (1 way) Has salivary and digestive glands herbivores & carnivores (predators & filter feeders) circulatory system transports nutrients and oxygen Heart pumps blood to all tissues Most have open circulatory system (leaky), cephalopods a closed circulatory system

5. Nervous system simple to complex Most have separate sexes Some species are hermaphrodites External fertilization- bivalves, chitons, & some snails – Sperm & eggs are released into water Internal fertilization-cephalopods & most snails – Cephalopods have modified arm to transfer sperm to female

7. class Gastropoda Snails-”stomach foot” Largest group Approx 90,000 species Mostly marine Body is coiled up inside shell Shell sits on a ventral foot

9. Nudibranch (sea slug- no shell) Tulip snail (with shell)

10. Body Structure thin layer of tissue that produces the shell muscular, used in locomotion some are well developed & have eyes area with small teeth used in scraping algae or other food from surfaces, made of chitin hard plate used to close opening once head/foot retracts into shell Gas exchange is through gills MantleFootHeadRadulaOperculum

12. class Bivalvia Oysters (cement themselves to hard surface) Clams (burrow) Mussels (attach to rocks using byssal threads), Body compressed between two shells Very large source of food for humans and other marine animals.

13. class Cephalopoda-2 in to 30 ft Cephalopods-most complex brain of all invertebrates – considered intelligent and capable of learning Most cephalopods display color changes correlated to certain behaviors Hectocotylus-Specialized arm transfers a spermatophore (packet of sperm) After eggs hatch female usually dies

14. Blue-ringed Octopus (Hapalochlaena) giant pacific octopus - Octopus dofleini

15. Giant Squid