Mollusks

1. Mollusks Cephalapods, Gastropods, and Bivalves

2. Mollusks • Includes octopus, cuttlefish, squid, sea slugs, snails, and bivalves (clams, oysters) • All mollusks have a three-part body plan • A foot, a head, a visceral mass (containing organs) • Includes different groups: • Cephalopods – includes octopus, squid, cuttlefish, and nautilus • Gastropods - conchs and snails (one shell) • Bivalves – mussels, oysters, clams, scallops (two shells)

3. Cephalopods

4. Cephalopod video

5. Cephalopods • 800 living species • They are the most intelligent invertebrates • Reproduce sexually • A courting male will approach a female with the brightest flashing colors, in some species • Male hand over a sperm packet to the female with tentacles.

6. Cephalopods • With the exception of the nautilus and some octopus species, all cephalopods have an ink sac, which can be used to expel a cloud of dark ink to confuse predators • All species have a beak • They feed by capturing prey with their tentacles, drawing it in to their mouth and taking bites from it • In some species, the beak is poisonous

7. Octopus • An octopus has a soft body and eight arms. • Each arm has two rows of suction cups. • Can regenerate lost arms • Live in dens that they make for themselves, within rocks or holes they dig under large rocks

9. Octopus • During reproduction, female stays with the eggs inside her den and doesn’t leave for any reason • Once they hatch, she will likely die • Most complex brain of the invertebrates • Have a memory, can learn to solve problems, and have been shown to figure out how to escape from tanks

10. Octopus • Feed on small crabs, fish, turtles, shrimp • Can paralyze with poisonous beak • Uses beak to open shells • Hunt mostly at night • Predators include eels, sharks, and dolphins • Adaptations for survival: • Can squirt ink at predators • Ability to change skin color • Squeeze into tight spots

12. Australian Blue-ringed octopus • About the size of a golf ball as an adult • Carry enough poison to kill 26 adults within minutes • Found in the Pacific only

13. Giant Pacific Octopus • The Giant Pacific Octopus • Largest octopus in the world • 23 ft from arm to arm

14. Squid • Some have bioluminescent organs - glow in the dark • Reproduce similar to octopus, but no care of eggs • Squid eat fish, crustaceans, and smaller squid • 10 tentacles – 2 longer ones used to catch prey • Eaten by sharks, fish, squid, and people • Also squirt ink and change color to blend in

16. The Giant Squid • Lives in the deep sea (300-600 meters deep) • Size of a bus (largest recorded – 60 feet) • Eyes the size of basketballs • Long tentacle can be 33 ft • Hunted by the sperm whale

18. Cuttlefish • Largest species reaches 20 in • Regulates buoyancy by changing its gas-to-liquid ratio in the chambered cuttlebone • Often called the "chameleons of the sea" because of their remarkable ability to rapidly alter their skin color at will

19. Nautilus • Have more tentacles than other Cephalopods, up to 90 • No suckers • The only cephalopods with an external shell

20. Gastropods • A gastropod is a mollusk with a single external shell • Calcium carbonate shell is produced by extracting calcium from water • Most shells spiraloutward as they grow • Use the tip of their foot, the operculum, to propel themselves forward in a "hopping" motion • Conchs are herbivores • Grazeon sea grass beds

21. Florida Queen Conch • Good to eat • In the 1970’s the conch fisheries completely collapsed in Florida, after overfishing • Commercial harvest banned in 1975, has been slow to recover in Florida

22. Bivalves • A bivalve is a mollusk with two shells, hinged and held together by an adductor muscle • Often referred to as shellfishand are an important part of the seafood industry • Reproduce by spawning • Most are filter feeders, and can be used as indicatorsof water quality • If water is dirty or polluted, it will show in the health of the bivalves • Many predators have methods of eating bivalves • Sea stars use strong arms and persistence to pry open • Whelks drill neat circular holes to access the meat inside • Birds (such as Oyster Catchers) can break open the shells

23. Clams • Usually occur in groups in soft sediment, where they burrow down • Clams feed on plankton through a double-tubed siphon • Siphon can be up to 1 ft long for clams buried deep in mud • Water (and plankton) is pumped through one siphon, into the body where any food is filtered out. Wastes and water are pumped out through second siphon • Siphon is also used for spawning, to eject sperm and eggs

24. Giant Clams • Found from South Pacific and Indian Oceans • Largest can be 4 ft (500 ft) • During the day they open their shells to let light hit their tissues, where symbiotic algae (like the zooxanthellae in corals) lives

25. Scallops • Can swim by rapidly opening and closing its shell • also use this technique to squirt water at predators • Atlantic Bay Scallop is found here • Rows of blue eyes • Edible

26. Mussels • A mussel is forever attached to a hard substrate by threads called byssus • Attach to mangrove roots, oyster clumps, rocks, etc. • Green mussel is an invasive species • Moved into Tampa Bay in past 10 years, and has slowly moved south

27. Oysters • Typically found in estuaries • Tolerant to changes in temperature and salinity • Occur in ‘clumps’ that make up oyster reefs • Filter feeders, feeding on plankton and nutrients in water • Filter up to 50 gallons a day • Because they filter so much water, oysters can indicate the water quality • Also makes them vulnerable to disease

28. Oysters spawn as water temperatures begin to rise • Juvenile oysters, called spat, settle onto a hard substrate and remain there for life • Oyster shells give off a chemical ‘scent’ that directs juveniles where to settle (this is how reefs form) • Oyster reefs are an important benthic community in Florida • Home for many fish, crabs, worms, etc. • Provide substrate for anemones, mussels, and barnacles