Phylum Mollusca , Class Cephalopods

1. Phylum Mollusca, Class Cephalopods • Cephalopods (Class Cepahlopoda) are a group of molluscs that include squid, nautilus, cuttlefish and octopus • They are the most highly evolved of all molluscs; nearly all are agile swimmers with a complex nervous system • Cephalopods have a reduction in or loss altogether of the shell

2. Phylum Mollusca, Class Cephalopods • Cephalopods (which means “head-footed”) have heads surrounded by a foot modified into arms and tentacles, usually equipped with suckers that are used to capture prey

3. Phylum Mollusca, Class Cephalopoda • Largest of all Molluscs • All have a radula, beak-like structure • Cephalopods have large eyes, with acute vision, extremely sensitive to slight details and impressions

4. Phylum Mollusca, Class Cephalopods • Cephalopods pump water through the siphon, or funnel into their mantle cavity • By forcing water out of the mantle cavity through the siphon, cephalopods swim by means of “jet propulsion” • By changing the direction of the siphon, cephalopods can move backward or forward, or can remain motionless in one place

5. Jet Propulsion Water enters mantle cavity Direction of water out of siphon Water exits from funnel or siphon Direction of cephalopod motion

6. Octopus: Order Octopoda • One of the most iconic cephalopods is the octopus • Octopuses have 8 long arms (“octo” means 8) and no shell • Common bottom dwellers, they are efficient hunters • Bite their prey (mostly shellfish) with a pair of beak-like jaws • Ink sac emits a dark cloud of fluid to deter predators

7. Squids: Order Teuthoidea • Squids are better adapted for swimming than octopuses • Squids have two triangular fins modified for swimming • Elongated body • Squids have eight arms & 2 tentacles, all with suckers which circle the mouth Long & retractable http://cas.bellarmine.edu/tietjen/images/Image32.gif

8. Squids: Order Teuthoidea • Suckers only at broadened tips on tenacle • The shell is reduced to a stiff pen embedded in the upper surface of the mantle

9. Cuttlefish: Order Sepiida • Cuttlefish are among the most intelligent invertebrates • Cuttlefish have a calcified internal shell called a cuttlebone, which aids in buoyancy • Chambered, gas-filled • Called “chameleons of the sea” for their astonishing ability to change skin color at will

10. Chromatophores • Cephalopods control their skin pattern and color by way of chromatophores • Chromatophores are pigment-containing and light-reflective cells used for camouflage • Inside the chromatophore, pigment granules are enclosed in an elastic sac • To change color, the sac is distorted by way of muscular contraction

11. Nautilus: Order Nautilida • Nautilus are called “living fossils”; only 6 species remain of an extinct superfamily • Survived relatively unchanged for millions of years • Gas-filled chambers aid in buoyancy • Paper nautiluses are actually pelagic octopus; named for the paper-thin eggcase in females

12. You will never be as cool as a cephalopod • Mimic octopus http://www.youtube.com/watch?v=H8oQBYw6xxc http://www.youtube.com/watch?v=ygh1-ul6E94 • Vampire squid from hell http://www.youtube.com/watch?v=S3CJIKKSUpg www.islandream.com/sangalakigallery7.htm http://www.itsnature.org/sea/other/colossal-squid/ www.flickr.com/photos/maxcdc/3615629745/

13. …or as smart??? • Octopuses and cuttlefishes have a remarkable capacity for learning • Giant nerve fibers rapidly conduct impulses allowing cephalopods to capture prey or escape at amazing speeds • Most cephalopods display color changes correlated with particular behaviors and moods • Octopus are known to use tools, and predict World Cup champions!