Phylum Phylum MolluscaMollusca

Phylum MolluscaPhylum MolluscaMollusks are soft-bodied animals that usually Mollusks are soft-bodied animals that usually

have an internal or external shell.have an internal or external shell.Mollusks include:Mollusks include:

- SnailsSnails- SlugsSlugs- ClamsClams- SquidsSquids- OctopusOctopus

Mollusca CharacteristicsMollusca Characteristics Soft bodySoft body External or internal shell- External or internal shell- Muscular foot and visceral mass (covered by Muscular foot and visceral mass (covered by

mantle)mantle) Radula in some-used to scrape foodRadula in some-used to scrape food Bilateral symmetry Bilateral symmetry No segmentsNo segments CoelomatesCoelomates Open circulatory system- blood not always in Open circulatory system- blood not always in

a vessela vessel Trochophore larvaeTrochophore larvae

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Trochophore larva-Trochophore larva-paddlelike, bristlespaddlelike, bristles

Apical tuftApical tuft

MouthMouth

AnusAnus

Ciliary bandCiliary band

StomachStomach

Phylum Mollusca: AnatomyPhylum Mollusca: Anatomy The body plan of The body plan of mostmost have 4 parts: have 4 parts:

mantle, shell, visceral mass, and foot.mantle, shell, visceral mass, and foot.

1.The 1.The mantlemantle is a thin layer of tissue that covers is a thin layer of tissue that covers most of the mollusk’s body like a cloak. most of the mollusk’s body like a cloak.

Phylum Mollusca: AnatomyPhylum Mollusca: Anatomy

2. The 2. The shellshell is made by glands in the mantle that is made by glands in the mantle that secretes calcium carbonate.secretes calcium carbonate.

-- Reduced or lost in slugs -- Reduced or lost in slugs

-- Internal or lost in Cephalopods -- Internal or lost in Cephalopods (squid/octopus)(squid/octopus)

Phylum Mollusca: AnatomyPhylum Mollusca: Anatomy3. 3. Visceral massVisceral mass is just beneath the mantle and is just beneath the mantle and consists of the internal organs.consists of the internal organs.

Phylum Mollusca: AnatomyPhylum Mollusca: Anatomy4.4. The muscular The muscular footfoot takes many forms: takes many forms: flat structures-crawlingflat structures-crawling

spade-shaped- burrowingspade-shaped- burrowing

tentacles-capturing prey.tentacles-capturing prey. clip-clip-giant octopus capturing preyl

Phylum Mollusca: FeedingPhylum Mollusca: Feeding Some Mollusks have a Some Mollusks have a radularadula: a rough, tongue-: a rough, tongue-

like organ with rows of teeth-like structures. like organ with rows of teeth-like structures. -scrape algae off surfaces-scrape algae off surfaces- rasp up flesh from prey.- rasp up flesh from prey.

Body SystemsBody Systems Muscular-SkeletalMuscular-Skeletal - outer shell, soft body, muscular foot - outer shell, soft body, muscular foot

for movement. for movement. DigestionDigestion food brought in through a siphon system food brought in through a siphon system

mouthmouthdigestive gland digestive gland intestineintestineanus.anus. NervousNervous-- A Mollusk has no formal nervous system, but has A Mollusk has no formal nervous system, but has

a series of ganglia that conduct impulses. a series of ganglia that conduct impulses. CirculatoryCirculatory - heart, blood and blood vessels, open- heart, blood and blood vessels, open RespiratoryRespiratory-- tubes called siphons- bring water in and out of tubes called siphons- bring water in and out of

their bodies to take in oxygen and give off carbon dioxide. their bodies to take in oxygen and give off carbon dioxide. gills- help with this. gills- help with this.

• ReproductiveReproductive- separate males and females and reproduces - separate males and females and reproduces sexually with a large gonad.sexually with a large gonad.

• ExcretionExcretion-- nephridium that gets rid of wastesnephridium that gets rid of wastes anus anus

Classes of MollusksClasses of Mollusks There are 8 classes of Mollusks (Covering 5)There are 8 classes of Mollusks (Covering 5)

Class Class Monoplacophora: Monoplacophora: placo=-plate; mono = oneplaco=-plate; mono = oneClass Class PolyplacophoraPolyplacophora: : ChitonChiton

Class Class GastropodaGastropoda: snails, slugs, & sea hares: snails, slugs, & sea hares

Class Class BivalviaBivalvia: clams, oysters, mussles & : clams, oysters, mussles & scallopsscallops

Class Class CephalopodaCephalopoda: octopus, squids, cuttlefish, : octopus, squids, cuttlefish,

& nautilus& nautilus

Class MonoplacophoraClass MonoplacophoraMono= oneMono= onePlaco=platePlaco=platePhora= to have or bearPhora= to have or bearMollusks with a single, curved shellMollusks with a single, curved shellMarineMarineThought to be extinct until one was found Thought to be extinct until one was found

in 1952in 1952

Class PolyplacophoraClass PolyplacophoraPoly = many placo= platesPoly = many placo= platesshell is divided into 8 curved plates shell is divided into 8 curved plates or shellsor shells Marine Marine Have a reduced head and a flattened footHave a reduced head and a flattened footEx. ChitonEx. Chiton

PolyplacophoraPolyplacophora When disturbed, the edges of the mantle When disturbed, the edges of the mantle tightly grip the substrate creating a powerful tightly grip the substrate creating a powerful vacuum that holds the chiton in placevacuum that holds the chiton in place

Has the ability to roll into a ball when dislodgedHas the ability to roll into a ball when dislodged

Quick Check: Quick Check:

Compare and contrast Class Compare and contrast Class Monoplacophora with Class Polyplacophora.Monoplacophora with Class Polyplacophora.

(How are they similar? How are they (How are they similar? How are they different?)different?)

Class BivalviaClass Bivalvia Clams, Oysters, Mussels & ScallopsClams, Oysters, Mussels & Scallops

Live in water, filter feedingLive in water, filter feeding2 shells held together by powerful 2 shells held together by powerful

muscles(hinges)muscles(hinges)No radulaNo radulaHatchet shaped foot for Hatchet shaped foot for burrowingburrowing

Class BivalviaClass Bivalvia

only Mollusks that do NOT have a radulaonly Mollusks that do NOT have a radula

Feed by siphoning and filtering large particles Feed by siphoning and filtering large particles from water from water

Can survive for short times out of water by Can survive for short times out of water by closing their valves closing their valves

Scallops can move around by flapping their Scallops can move around by flapping their shells when threatened.shells when threatened.

Class BivalviaClass Bivalvia

Starfish, many sea birds (Oyster Catchers, willets, Starfish, many sea birds (Oyster Catchers, willets, plovers, and much more), and walrus feed on themplovers, and much more), and walrus feed on them

• The largest bivalve is the Giant clam (clip)The largest bivalve is the Giant clam (clip) Can weigh more than 450 lbsCan weigh more than 450 lbs

Oyster Catcher Willet Plover

Class Bivalvia: Making PearlsClass Bivalvia: Making Pearls Oysters filter-feedOysters filter-feed

An irritant, such as a grain of sand, becomes An irritant, such as a grain of sand, becomes embedded in the mantle.embedded in the mantle.

The animal coats the irritant with the same materialThe animal coats the irritant with the same material used to produce the lining of its shell called used to produce the lining of its shell called mother-mother- of-pearlof-pearl..

The coating makes the irritant less painful.The coating makes the irritant less painful.

It continues to coat the irritant, creating a It continues to coat the irritant, creating a pearlpearl. .

Class BivalviaClass BivalviaImportanceImportance

Bivalves are filter feeders Bivalves are filter feeders

valuable service by reducing suspended particles in valuable service by reducing suspended particles in their habitatstheir habitats

If their populations are reduced, the water in that area If their populations are reduced, the water in that area will become will become turbidturbid (cloudy) (cloudy)

Turbid water reduces light penetration for Turbid water reduces light penetration for photosynthesis in sea-grasses and algaephotosynthesis in sea-grasses and algae

Without plants, many other populations of organisms Without plants, many other populations of organisms will also decreasewill also decrease

Class Bivalvia: Eating BivalvesClass Bivalvia: Eating Bivalves ““Oysters on a half-shell”Oysters on a half-shell”Considered an aphrodisiac Considered an aphrodisiac Eaten fried, Steamed, or rawEaten fried, Steamed, or raw

Mmmmm….

Mmmmmmm…

GOOD!

Class GastropodaClass Gastropoda Gastropoda means “stomach foot”Gastropoda means “stomach foot” Includes snails, slugs, & sea haresIncludes snails, slugs, & sea hares

Most are Most are singlesingle shelled- asymmetrical and shelled- asymmetrical and coiledcoiled

Some are shell-less Some are shell-less (slugs & sea hares)(slugs & sea hares)

Radula for scraping foodRadula for scraping food

Class GastropodaClass Gastropoda

They are 2They are 2ndnd only to insects in their number of only to insects in their number of known speciesknown species

They can live in gardens, woodland, deserts, They can live in gardens, woodland, deserts, rivers and lakes; estuaries, mudflats, the rocky rivers and lakes; estuaries, mudflats, the rocky intertidal, the sandy subtidal, in the depths of the intertidal, the sandy subtidal, in the depths of the oceans, and many other ecosystemsoceans, and many other ecosystems

queen-conch/strombus-gigas/video-00.htmlqueen-conch/strombus-gigas/video-00.html

Class GastropodaClass Gastropoda They move using a muscular footThey move using a muscular foot

Many have 2 or 4 tentacles Many have 2 or 4 tentacles with eyes on the tipwith eyes on the tip

Most have a coiled shell that Most have a coiled shell that opens to the rightopens to the right

The Lightning Whelk is the only The Lightning Whelk is the only “ “left handed” snailleft handed” snailGastropod clip- Oahu tree snailGastropod clip- Oahu tree snail

Class GastropodaClass GastropodaMany have an Many have an operculumoperculum that is used as a that is used as a

“trap-door” to close the body inside the shell“trap-door” to close the body inside the shell

Most breath using gillsMost breath using gills

Class Gastropoda: ImportanceClass Gastropoda: Importance Many animals feed on gastropodsMany animals feed on gastropods

-- Example: Sea otters eat abalone-- Example: Sea otters eat abalone

Class GastropodaClass Gastropoda

Hermit crabs inhabit empty snail shells.Hermit crabs inhabit empty snail shells.When the crab gets too big for the shell, theyWhen the crab gets too big for the shell, they find a larger one. find a larger one. Hermit crabs have wars for prized shells.Hermit crabs have wars for prized shells.http://www.arkive.org/common-hermit-crab/http://www.arkive.org/common-hermit-crab/

pagurus-bernhardus/video-03.htmlpagurus-bernhardus/video-03.html

Class GastropodaClass Gastropoda Suborder NudibranchiaSuborder Nudibranchia

- Means “Naked gill”- Means “Naked gill”- marine, shell-less gastropods- marine, shell-less gastropods- The gills are arranged as feathery - The gills are arranged as feathery plumes on their backsplumes on their backs- Are brightly colored- Are brightly colored

Warning: many are poisonous Warning: many are poisonous CamouflageCamouflage

Quick Check: Quick Check:

Why are gastropods important? What would Why are gastropods important? What would happen if all gastropods went extinct?happen if all gastropods went extinct?

Class Class CephalopodaCephalopoda

Class CephalopodaClass CephalopodaTypically soft-bodied with the head attached to Typically soft-bodied with the head attached to

a single foot.a single foot.

The foot is divided into tentacles or arms.The foot is divided into tentacles or arms.

Cephalopoda LocomotionCephalopoda Locomotion Most swim by forcefully expelling water from Most swim by forcefully expelling water from

the mantle cavity through a ventral the mantle cavity through a ventral funnel (Siphon)funnel (Siphon)..

Swim using Swim using jet propulsion jet propulsion method.method.

Funnel can point forward or backward to Funnel can point forward or backward to control directioncontrol direction

The force of water expulsion determines speed.The force of water expulsion determines speed.

Cephalopoda FeedingCephalopoda Feedingbeaksbeaks: similar to a bird’s beak, used for : similar to a bird’s beak, used for

crushing and picking apart food.crushing and picking apart food.

Beak

““Masters of disguise!”Masters of disguise!”

-- Color changes are possible due to special -- Color changes are possible due to special pigment cells contained within its skin, called pigment cells contained within its skin, called

chromatophoreschromatophores..

CephalopodaCephalopoda

ChromatophoresChromatophores: small structures filled : small structures filled with colored ink which can be with colored ink which can be expandedexpanded and and contractedcontracted to communicate with to communicate with others or as camouflage against the others or as camouflage against the landscape.landscape.

CephalopodaCephalopodaColor changes are used for:Color changes are used for:

- Camouflage - Camouflage

- Communication (alarm/courtship)- Communication (alarm/courtship)

- Many are - Many are bioluminescentbioluminescent to attract prey to attract prey and mating partners!and mating partners!

Octopus are Highly IntelligentOctopus are Highly Intelligent Maze and problem-solving experiments have Maze and problem-solving experiments have

shown that they do have both short- and long-shown that they do have both short- and long-term memory.term memory.

Can be trained to distinguish between different Can be trained to distinguish between different shapes & patternsshapes & patterns

Observed having Observed having observational skillsobservational skills

Class CephalopodaClass Cephalopoda

OctopusOctopus::

- - Have 8 armsHave 8 arms

- Arms have sucking disks - Arms have sucking disks that grab & hold prey.that grab & hold prey.

- Blood is pale blue.- Blood is pale blue.

- The shell is absent!- The shell is absent!

Class CephalopodaClass CephalopodaMore More OctopusOctopus::

- When female lays eggs, she stops eating, - When female lays eggs, she stops eating, & protects her eggs until she dies.& protects her eggs until she dies.

Class CephalopodaClass CephalopodaBlue-ringed OctopusBlue-ringed Octopus::

- The most toxic- The most toxic- A bite is nearly always fatal to humans.A bite is nearly always fatal to humans.

Giant OctopusGiant Octopus::

- Can weigh 600 lbsCan weigh 600 lbs- Known to attack ROV and bite into metalKnown to attack ROV and bite into metal

Class CephalopodaClass Cephalopoda• People eat octopus: Dead or ALIVE!People eat octopus: Dead or ALIVE!

• A dish called “San Nakti” means “living A dish called “San Nakti” means “living octopus”octopus”-- Kind of difficult to get the octopus down because -- Kind of difficult to get the octopus down because

the tentacles stick to your mouth and throat. the tentacles stick to your mouth and throat.

-- They also have a tendency to walk off your plate!-- They also have a tendency to walk off your plate!http://www.gadling.com/2011/09/27/video-eating-live-http://www.gadling.com/2011/09/27/video-eating-live-

octopus-in-korea-warning-graphic/octopus-in-korea-warning-graphic/

Cuttlefish & SquidCuttlefish & Squid

Have 10 appendages (decapods): Have 10 appendages (decapods):

8 arms with suckers and 2 8 arms with suckers and 2 long retractile tentacleslong retractile tentacles

Forms of CephalopodaForms of CephalopodaCuttlefishCuttlefish: :

-- Have an internal gas filled “bone” that helps-- Have an internal gas filled “bone” that helps with buoyancy called the with buoyancy called the cuttlebonecuttlebone..

-- Well, it is not for sharpening the beak. It's -- Well, it is not for sharpening the beak. It's amazing how many pet owners think this is its amazing how many pet owners think this is its purpose. Cuttlebone is provided to birds as a purpose. Cuttlebone is provided to birds as a source of source of calciumcalcium and other necessary and other necessary minerals. It is especially important to breeding minerals. It is especially important to breeding hens. hens.

Forms of CephalopodaForms of Cephalopoda

SquidSquid::

-- Color changes reflect the animal’s mood.-- Color changes reflect the animal’s mood.

-- Messages: -- Messages: ready to mate, sexual identification, alarm, ready to mate, sexual identification, alarm, ready to hunt, & hiding.ready to hunt, & hiding.

Cephalopoda: SquidCephalopoda: SquidSquidSquid::

Most of the shell has disappeared, leaving only Most of the shell has disappeared, leaving only a thin, horny strip called a a thin, horny strip called a penpen which is which is enclosed in the mantle.enclosed in the mantle.

CephalopodaCephalopodaSquidSquid::

Giant SquidGiant Squid are the largest are the largest invertebrateinvertebrate

Have the largest eyes in Have the largest eyes in the animal kingdomthe animal kingdom

Never been seen alive!!!Never been seen alive!!!

Their bodies wash up onto Their bodies wash up onto beachesbeaches

Sperm whales feed on giant squidSperm whales feed on giant squid

Giant SquidGiant Squid

Forms of CephalopodaForms of Cephalopoda NautilusNautilus

Forms of CephalopodaForms of CephalopodaNautilusNautilus

-- Sticking out from the shell is the nautiluses’ -- Sticking out from the shell is the nautiluses’

arms and a leathery arms and a leathery hoodhood that closes the that closes the animal into its shell for protection. animal into its shell for protection.

-- This nautilus has more than 90 arms. -- This nautilus has more than 90 arms.

Forms of CephalopodaForms of CephalopodaMore More NautilusNautilus::

-- The only cephalopod encased in a shell.-- The only cephalopod encased in a shell.

-- The nautilus can fill the chambers it doesn’t -- The nautilus can fill the chambers it doesn’t occupy with occupy with gasgas or or waterwater. If the chambers are . If the chambers are filled with gas, the animal will float. If the filled with gas, the animal will float. If the chambers are filled with water, the animal will chambers are filled with water, the animal will sink. sink.

Forms of CephalopodaForms of Cephalopoda

More More NautilusNautilus::

-- The living animal inhabits only the last -- The living animal inhabits only the last chamber.chamber.

-- As it grows, it moves forward, secreting -- As it grows, it moves forward, secreting behind it a new septum.behind it a new septum.

-- The chambers are connected by a cord of -- The chambers are connected by a cord of living tissue called a living tissue called a siphunclesiphuncle, which , which extends from the visceral mass.extends from the visceral mass.

NautilusNautilus

Quick CheckQuick Check

How are squid different than octopus? How are squid different than octopus?

Table 1 Classes of the Phylum Mollusk

Scientific Name Pronunciation

Common Name # Shells Foot # of

Species

Polyplacophore chitons 8-plates ~650

Monoplacophores 1 ? extinct

GastropodaGAS-troh-pahdz

univalves (snails, slugs)

1 or none

stomach foot ~90,000

Bivalvia [Pelecapoda] bivalves 2 hatchet foot ~8000

CephalopodaSEHF-uh-loh-pahdz

octopus, squids internal head foot ~650

The End of MolluscaThe End of Mollusca

Polyplacophore (many plates). [Amphineura].