Phylum Mollusca

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Phylum Mollusca

• the soft bodied invertebrates

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General Features
1. most live in water
2. most have valves (shells)
3. bilateral symmetry
4. coelom (coelomates)
5. mouth and anus
6. muscular foot (tentacles)
7. mantle (secretes the shell)
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Mollusk
Classification
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Mollusks
Kingdom
Animalia
Phylum
Mollusca
Class
Snails, Slugs -
Gastropoda
Clams, Oysters -
Bivalvia
Octopus, Squid -
Cephalopoda
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Class Gastropoda
Gastropods live in water and on land.
Land Snail
Pond Snail
Land Slug
Sea Slug
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Gastro stomach pod foot
Snails have a well-developed muscular foot.
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Snails eat using a mouth structure called a
radula.
Close-up of radula
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Land species are usually hermaphrodites! Why?
It makes it easier to find a mate!
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Slugs have no shell.
respiratory pore
mucus prevents drying out
tentacles
eyespots
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Class Bivalvia clams, oysters, scallops,
mussels, etc.
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Bi two valve shell
2 shells
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Clams have an open circulatory system.
The blood leaves the blood vessels and flows
through the coelom.
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Scallops have many eyespots!
eyespots
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Zebra Mussels
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Class Cephalopoda octopus, squid, and nautilus
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Cephalo head
pod foot
head
foot
(tentacles)
Cephalopods have a well-developed head and foot
(tentacles).
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Whereas octopi have 8 tentacles,
squids have 10 tentacles.
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Cephalopod Eyes
Although the pupils are shaped differently,
cephalopods have well-developed eyes (not
eyespots).
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The cephalopods have a very sharp beak for
crushing food between their tentacles.
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Octopi
The blue ringed is extremely poisonous.
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The Octopus
Smartest known Invertebrate!
excurrent siphon
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Squid
Squid are excellent predators using their
tentacles with suckers to capture prey.
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Squid are capable of very quick bursts of speed.
This one was caught going after a fishing lure.
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Cuttlefish
A cuttlefish looks like a squid but with shorter
tentacles and a wider body.
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cuttlefish
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cuttlefish
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Chambered Nautilus
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The nautilus is the only cephalopod with a shell.
The shell is used to control its depth in the
water.
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How the Chambered Nautilus Controls Its Depth
old chambers filled with air
chamber being used as a home
Air is pumped in or out of the old chambers.
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The End