Cephalopods

• they are the smartest, largest and fastest

• radulla: teeth used to scrape or drill holes • mantle: covers body and produces shell • foot to move

• modified foot: arms and funnel - mouth with a beak

• chambers added as they grow • chambers allow for buoyancy to be altered and to maintain upright position • counter-shading for camoflage • siphuncle perforations through the septa

• digital tentacles: anchor • lateral tentacles: grope around • median tentacles to move food to mouth

• increased surface area with lamella (ridges) and ciliary fields • the cilia for mechanosensory are shorter • the cilia for chemosensory are longer

• pinhole camera • light travels through the hole and arrives at a point on the back of the eye which is composed of light sensitive cells

• if eyes small: focused but dim • if eyes large: bright but fuzzy • must produce mucus from goblet cells to clear pathogens from the eye (since seawater and sediment gets in)

• Muntz et al • nautilus put in tank surrounded by drum with stripes • if the nautilus could perceive the stripes it would turn with the drum to orient itself • minimum visual resolution between 5 and 11 degrees (two objects must be more that 5 degrees apart to be perceived)

• nautilus: shells • squid: flexible rod • octopus: beak • cuttlefish: bone

• shoot water out funnel - can aim funnel to direct themselves

• closed circulatory system - supports their active lifestyle

• higher risk of being eaten - better manuverability

• two long tentacles • end called tentacle clubs and contain suckers • tentacle stalk

• lens to focus light • lens is moved back and forth to focus light • light enters eye and hits the photoreceptors at the back • octopuses are able to see polarized light because of microvilli

• complex statocytes that are made up of base, macula, and three cristae • cristae detect angular acceleration • macula detects forward acceleration • to gain information about body position and movement

• lateral lines that contain hair cells that detect movement in water • useful for avoiding predators

• chromatophores: sacs filled with pigments (black, brown, red, orange, yellow) • chromatophores are under nervous system control and are connected to radial muscle fibers • reflecting cells: located below chromatophores and three different types (blue and green, iridophores: pink, yellow, green, blue and silver, leucophores: white spots) • stellate ganglion relays from brain to change colour pattern

• mimic octopuses change their behaviour to appear like flounders, lion fish, and sea snakes

• ink jet to produce curtain - photophores are bioluminescent and may be involved in mating or defense

• they use temperature • warmer in shallow water: green • colder in deeper water: blue

• see colour - live in the deep so only see bioluminescents

• female detects fitness level of potential mates with chemosensory • if chosen she cracks their sperm packet over her eggs • she airates the eggs until they hatch and then she dies

• larger brains compared to body weight then fish and reptiles but less than birds and mammals