Station

1
Station 1General Characteristics of the Phylum
Molluscasoft bodied

• 1. Bilateral Symmetry
• 2. Head region developed in snails squid
  (reduced in clams)
• 3. Digestive tract complete so what do they
  have?...
• 4. Rasping organ (radula)
• 5. Dorsal heart, open circulation make sure you
  remember what that means (except for
  cephalopods)
• 6. Gills, mantle cavity, or epidermis for
  respiration
• 7. Metanephrida do you remember the function for
  the nephridia?
• 8. Dioecious, Monoecious

2
Station 2Habitat Economic Importance

• Habitat Marine, fresh water, terrestrial
• Economic importance Food, Pearls, parasitic
  hosts, damage ships, damage gardens

3
Station 3Main Body Parts

• Reduced to its simplest dimensions, the mollusk
  body plan is divided
• into two parts Head-Foot portion and Visceral
  Mass.
• The head-foot portion contains the head and
  locomotor organs go figure.
• The Visceral Mass contains the digestive,
  circulatory, respiration, and reproductive
  organs.
• 1. Shell (label)
• 2. Visceral mass or hump
• 3. Foot
• 4. Head
• 5. Radula (label)
• 6. Mantle (label)
• Also label Gill, heart, coelom, intestine,
  nephridium

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Station 4Mantle

• Mantle extends from visceral hump secretes
  shell protects respiratory organs
• Mantle cavity may serve as a respiratory organ
  for terrestrial species provides JET propulsion
  in cephalopods (squids/octopus)

5
Station 5Foot, Radula, Shell

• Foot functions in movement attaching food
  capture
• Radula present in all except bivalves (clams)
  rasping tongue-like structure
• odontophores - supporting cartilages of radula
• Shell three layers also termed VALVE
• Periostracum outer horny layer protects
  underlying layers from erosion
• Prismatic layer calcium carbonate middle layer
  
• Nacre- pearly layer next to mantle FORMS PEARLS
  ?

6
Station 6Circulation, Excretion, Nervous

• Circulation open in all except cephalopods
• Open pumping heart, vessels, blood sinuses, no
  capillaries
• Closed in cephalopods (squid/octopus) heart,
  blood vessels, capillaries
• FYI Definition Blood sinus A broad,
  blood-filled passage bounded by a cell lining
  resembling that of capillaries.

7
Station 6 Continued

• Excretion A pair of metanephridia
• FYI (the difference between a nephridia and
  metanephridia is that in a metanephridia the
  inner end opens into the coelom)
• Nervous several pairs of ganglia with nerve
  cords well adapted brain in cephalopods
  (squid/octopus)
• Its sort of scary to think about squids and
  octopuses having a well adapted brain!!!

8

• Octopus Article

9

• In laboratory experiments, octopuses can be
  readily trained to distinguish between different
  shapes and patterns. Octopuses have also been
  engaged in what may be described as play
  repeatedly releasing bottles or toys into a
  circular current in their aquariums and then
  catching them. Octopuses often break out of their
  aquariums (and sometimes into others) in search
  of food. They have even gotten onto fishing ships
  and opened holds to eat crabs.
• In many countries, including the United States,
  octopuses are on the list of experimental animals
  on which surgery may not be performed without
  anethesia.
• Octopuses also have an excellent sense of touch.
  The octopus's suckers are equipped with
  chemoreceptors so that the octopus can taste what
  it is touching.
• The octopus does not seem to form a mental image
  of the overall shape of the object it is
  handling. It can detect local texture variations,
  but cannot integrate the information into a
  larger picture.
• The neurological autonomy of the arms means that
  the octopus has great difficulty learning about
  the detailed effects of its motions. The brain
  may issue a high-level command to the arms, but
  the nerve cords in the arms execute the details.
  There is no neurological path for the brain to
  receive feedback about just how its command was
  executed by the arms the only way it knows just
  what motions were made is by observing the arms
  visually. It is sometimes said that octopuses can
  "learn" to open jars, but this appears to be
  incorrect. The only thing that octopuses appear
  to be capable of learning about opening jars is
  to be persistent and vigorous.

10
Station 7Reproduction

• Reproduction eggs are fertilized in water with
  most mollusks
• Egg hatches into trochophore (free-swimming
  larvae)
• Then to veliger (has beginning of foot, shell,
  and mantle)

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Station 8Class Polyplacophoramany plate
bearers

• Ex Chitons
• 8 overlapping plates in shell use a foot to
  creep along

12
Station 9 Class Scaphopodahollow or
boat-shaped foot

• Commonly called tusk shells or tooth shells
• Tubular shell open at both ends with creeping
  foot used to burrow into mud or sand
• Found in subtital zone over 6000m in depth

13
Station 10Class Gastropodastomach foot

• Stomach-footed mollusk
• Largest, most successful group ?
• Ex Snails, Slugs, Conchs, Sea Slugs
• Most of these animals are usually sluggish
  because of a heavy shell
• Torsion moves mantle cavity to front of body
  and twists organs in 180 degree rotation occurs
  in veliger stage
• Advantage allows head to be drawn into shell
  for protection
• Disadvantage fouling (anus in a position to
  drop wastes on head and in front of gills ugh
  ?)
• Adaptations to avoid fouling
• Loss of right gill
• Elongated siphon
• Wastes expelled forcibly with air or water from
  lung
• Copy Figure 16-13 in your book!

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Station 11Class Gastropoda Continued

• Univalve one shell animal snail
• Feeding algae, plankton, scavenger, carnivorous
  
• FYI you do not need to write this part
• Members of the genus Conus eject toxins from
  their radula
• A snail may feed continuously for hours or days
  tearing away an oysters shell and flesh

15
Station 12Class Gastropoda Continued

• Respiration
• Gills
• Skin of mantle
• Nervous 3 pairs of ganglia act as brain
• Eyes
• Statocysts on end of tentacles balance
• Tactile organs on end of tentacles touch

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Station 13Class Gastropoda Continued

• Reproduction most are monoecious (may be
  dioecious depending on species) do you remember
  what those terms mean?
• Snails
• 1. Courtship use love darts to induce mating
• Eject a dart from a dart sac (figure 16-18) into
  the partners body to initiate reproduction.
  Some researchers believe it increases storage of
  sperm from the dart shooter sometimes for years
  after copulation insuring that the initial
  shooter fathers more offspring than future
  partners.
• 2. Exchange of spermatophore (packets of sperm)
• 3. Fertilized eggs from each snail are slowly
  deposited singly or in a jelly-like mass in a
  moist, dark area, where each zygote slowly
  develops and hatches into a tiny snail-complete
  with an even tinier and transparent shell of its
  own.

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Station 14Subclasses of Gastropods

• Prosobranchia- marine snails, some freshwater
  snails, and terrestrial gastropods
• Opisthobranchia nearly all marine (sea slugs,
  sea butterflies) live in shallow water
• Techtibranch Gastropod with gills and shell
• Nudibranch Gastropod with no shell or gill
• Palmonta land snails some freshwater snails,
  they have a lung

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Station 15 Class Bilvalviatwo shells

• Used to be called Pelecypoda means
  hatchet-footed
• Examples Mussels, clams, scallops, oysters, ship
  worms

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Station 16Class Bivalvia Continued

• Shell 2 valves held together by hinge ligament
  on dorsal side open/close by 2 adductor muscles
• Mantle posterior edges modified to form
  incurrent and ex-current siphons to regulate
  water flow in and out of shell
• Pearl formation a grain of sand gets trapped
  between mantle and nacre mantle secrets macre
  (mucus) around it to prevent irritation. The
  material solidifies to make the pearl!
• Locomotion foot except scallops which squirt
  water from their shell to move through the water

20
Station 17Class Bivalvia Continued

• Feeding filter feeder secrete mucus over
  gills food is trapped as water flows over gills,
  mucus transferred to mouth
• Nervous
• few species have eyes with cornea, lens, and
  retina at edge of shell others have OCELLI
  (eyespots) which are sensitive to light
• nerve cord
• statocysts
• chemoreceptors
• tactile receptors

21
Station 18Class Bivalves Continued

• Reproduction dioecious eggs are fertilized in
  water
• Marine Species egg hatches into trochophore
  then develop to veliger then to spat and finally
  adult
• Freshwater Species eggs fertilized in shell
  egg to zygote to glochidium (parasite on fish
  gills) to adult