Mollusks
Kingdom Animalia,
Phylum Mollusca
(means “soft”)
What is a Mollusk?
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Mollusks are extremely diverse!
Soft body with internal or external shell
Ex: snails, slugs, clams, squids, and
octopi
Trochophore larva
●Bilaterally symmetrical.
● Has a nervous system with a circumoesophagal ring, ganglia and paired nerve
chords.
● Has an open circulatory system with a
heart and an aorta.
● Has gaseous exchange organs called
ctenidial gills.
● Reproduce sexually
●Feed a wide range of material.
●Live in most environments.
●Despite their amazing diversity, all
mollusks share some unique
characteristics that define their body plan
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Body plan:
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Foot – takes on many forms
Mantle – covers the body
Shell – (present in most)
Visceral mass – internal organs
●https://www.youtube.com/watch?v=ZGIQ2
sCgEmE
Groups of Mollusks
Three major classes of mollusks
Gastropods
Bivalves
Cephalopods
Gastropod
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snails, slugs, and nudibranchs
Shell-less or single shelled
Move by a muscular foot
Some are poisonous, bright colors
Snail
Spiral
Mouth (radula)
●https://www.youtube.com/watch?v=u4QAn
CFd4iw
●https://www.youtube.com/watch?v=Go_LI
z7kTok
Slug
●https://www.youtube.com/watch?v=W9EV
a8p5b58
Nudibranchs
(sea slugs)
Check out the nudibranch gallery at nationalgeographic
●https://www.youtube.com/watch?v=cJELPcwtP8
Bivalves (things with 2 shells)
Such as clams, mussels, oysters,
and scallops. Bivalves are found in both
freshwater and marine environments.
●Burrowing Clam:
https://www.youtube.com/watch?v=6JyNp
PUj1ys
●Ask an Expert: mussels
https://www.youtube.com/watch?v=eq6XO
h_ML4M
●Pearls:
https://www.youtube.com/watch?v=tIOSW
AbUf74
Cephalopods
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octopi, squids, cuttlefish, and nautilus
soft-bodied , head is attached to foot
foot is divided into tentacles with sucking
disks
small internal shells or no shell at all
Many release ink
Well developed eyes
most complex of the mollusks
Octopus
(creeps on tentacles)
Octopus
●Active Predators
●Learn easily, including learning by
observation of another octopus
●Problem solvers
Octopus
●Fast swimmers, they can jet forward by
expelling water through their mantles. And
their soft bodies, with no internal or
external skeleton, can squeeze into
impossibly small cracks and crevices
where predators can't follow.
●The amazing mimic octopuses are
capable of changing their color body
shape to mimic other animals
Octopus
●Have beaklike jaws that can deliver a
nasty bite, and venomous saliva, used
mainly for subduing prey.
●They have been found to play with “toys”
and have personalities
●They have blue blood!!
Intro: https://www.youtube.com/watch?v=epbJi35lzEs
Octopus versus Shark: https://www.youtube.com/v/p9A-oxUMAy8
Octopus escapes jar:
https://www.youtube.com/v/PmDTtkZlMwM
Octopus camouflage:
https://www.youtube.com/v/PmDTtkZlMwM
Octopus Houdini:
https://www.youtube.com/watch?v=9yHIsQhVxGM
Cuttlefish
(the chameleon of the sea)
●https://www.youtube.com/v/2x-8v1mxpR0
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Nautilus is only cephalopod with shell
Squid have a modified shell called a pen
Like the octopus, squids also have parrotlike beaks
●https://www.youtube.com/watch?v=PIheR
Ycm6sI
Squid
●Giant Squid Documentary:
https://www.youtube.com/watch?v=Cs6Kq
pZ1PIE
●Biology Corner
●HumanKind. AnimalKind. OneKind.