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Mollusks
Characteristics of Mollusks
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Mollusks are invertebrates
Mollusks have soft bodies
Mollusks have bilateral symmetry
Mollusks have a digestive system with 2 openings
Mollusks have an open circulatory system
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THINK! – What does it mean to have an open
circulatory system?
Blood does not travel in vessels throughout the entire
body.
Structure of Mollusks
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Although they don’t look much alike at first, a snail, a
clam, and a squid have the same basic body structure.
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Shell – hard outer covering
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Gills – organs that remove oxygen from water
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Mantle – a thin layer of tissue that lines the internal
organs; it secretes the hard shell
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Digestive tract – stomach plus intestines
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Foot – used for crawling, digging, or catching prey
Groups of Mollusks: Gastropods
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Examples: Snails & Sea Slugs
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Characteristics:
• Has a single shell or no shell at all
• Eats using a radula, a flexible ribbon of tiny
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teeth to obtain food.
Moves by oozing mucus along its broad foot
Groups of Mollusks: Bivalves
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Examples: Oysters, Clams, Scallops, &
Mussels
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Characteristics
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They have 2 shells held together by
hinges
They are filter feeders that strain the
water for food
They do not move quickly; adults stay
in one place or use their foot to move
very slowly
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THINK! – Which bivalve do you think is
able to move?
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Clams dig into the mud by changing
the shape of its foot
Groups of Mollusks: Cephalopods
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Examples: Octopuses & Squids
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Characteristics:
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Captures its prey with muscular tentacles, crushes the
prey with its beak, and cuts the flesh with its radula
Has large eyes, excellent vision, and large brains. They
are capable of learning!
They swim by jet propulsion squeezing water out of a tube
called a siphon
Mollusks In the News and Video
For many years, it has been rumored that
giant squid existed but only dead
carcasses of a few have been found
along some beaches. None have been
seen alive. Until now…
Live Giant Video_0113
Mollusks In the News and Video
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A study emerged in March 2008 in which
scientists have found that the hard and soft
materials of a Humboldt squid’s beak may be
used to improve artificial limbs for humans.
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The squid’s beak is like placing a razor blade in
a bowl of Jell-o but, because the beak is soft
towards the bottom and sharp only towards the
top, it does not harm the squid’s body but can
still pierce its prey.
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“We could maybe imagine creating a full
prosthesis that mimics the chemistry of the beak,
so that it matches the elasticity of cartilage on one
side and on the other side you could create a
material which is very stiff..”
VIDEO – Smartest Animals_Octopus &
Squid? 4min2sec
Deep-Sea ‘Dating’ Video Clip
Amazing Fish Changes Its Stripes
Cuttlefish Dating
http://abcnews.go.com/search?searchtext=squid&type=