Class Cephalopoda

• Shell divided by septa, with chambers

  connected by the siphuncle
• Siphuncle- refers to the internal tube

  that connects the chamber of the shell
• In nautiloids, it runs in the center of the

  shell chamber while in ammonoids it is

  found along the outer edge of the shell.
• Shell reduced or lost in many species.
• Shell can be reduced: the internal shell

  of squids has a chitinous endoskeleton

  (plastic-like) called gladius or pen

  whereas cuttlefishes have a calcareous

  endoskeleton.
• Shell can be lost in octopus
• Closed circulatory system
• Blood remains inside the blood vessels
• hemocyanin in blood
• Hemocyanin

  • copper-containing pigment
• Hemocyanin

  • can also be found in other invertebrates, mostly in arthropods (crustaceans)
• Hemocyanin

  • Blueish when oxygenated and colorless when nonoxygenated.
• Hemocyanin

  • The oxygen-carrying protein in the hemolymph of this group
• Hemocyanin

  • Found in the liquid portion of their blood, it is extracellular.
• complex chambered heart

  • 3 chambered with 2 auricles and 1 ventricle
• Absence of cilia in gills
• Gills- used primarily for gaseous

  exchange
• In other mollusks (bivalves and

  gastropods) the function of gills is to

  fold for respiration and filter feeding.
• Once food is trapped by mucus in

  the gills, then moved by the mouth

  by the cilia.
• Foot modified to form flexible arms and siphon
• Octopus has 8 arms covered with

  suckers ventrally, wider at the base,

  gradually tapering
• Octopus arms

  • Function: olfactory function, walking, grabbing prey, hanging not coral reefs
• Superorder Octopodiformes
• Ganglia fused to form a large brain encased in a cartilaginous cranium
• Have well-developed sensory and motor

  function
• Considered to be the most cognitively

  advanced group of the invertebrates
• Based on studies, they can solve

  complex puzzles and mazes, have

  elaborate courtship rituals, they can

  camouflage, and communicate by

  changing the color and pattern of their

  skin.
• Other characteristics: large, active

  predator that can swim above the sea

  floor to catch prey and avoid predators
• Usually dioecious
• spermatophore common
• Spermatophore can also be produced

  by certain groups of fish
• without larva
• no trochophore
• Chitinous beak/radula

  • Used to reduce large food
• chromatophores/ink gland

  • Chromatophores – pigment cells for camouflage, can be used for identification purposes and communication between animals
• chromatophores/ink gland

  • Ink gland – used to evade enemies, not only in squid but also in octopus and cuttlefish
• They are Carnivorous
• 17,000 named species of fossil cephalopods and 800 identified living species
• Cephalopoda shell

  
• Evolute

  • Coiled shell in which the whorls touch but do not overlap