Download The Phylum Molluska - MUGAN'S BIOLOGY PAGE

The Phylum Molluska
By: Zach Lashbrook
& Sarah Briggs
Different Types of Mollusks
• Cephalopods
• Gastropoda
• Bivalvia
• Polyplacophora
• Octopus
Cephalopoda
• Squid
• Cuttlefish
Octopuses & Squids
Gastropoda
gastro means stomach or belly
pod means foot
•
•
•
•
•
Snails
Whelks
Periwinkles
Abalone
Slugs
Bivalvia
• Clams
• Scallops
• Oysters
• Mussels
Polyplacophora
The Habitat
• They are marine animals
• Some found in coastal areas and others
in the deepest parts of the ocean
• Most live in the bottom sediments
The Habitat
• Cephalopods they are primarily freeswimming species
• A lot mollusks inhabit rocky seashore
environments where their low domeshaped shells are well suited.
• Some have been found at depths of
2,200 feet or more
Examples of their food source
•
•
•
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They eat most anything
Different Mollusks eat different things
Snails eat leaves
Some carnivores and eat other mollusks
and worms
• Squid are predators
How are they important to
humans?
• And a lot of mollusks such as squids,
snails, octopuses, and clams provide us
with food
• Their pearls can be used for jewelry
• Their shells can be used for tools,
decorations, containers, musical devices,
etc.
How are they important to the
environment?
• They are a major part of the food chain
• They are both predators and prey
• Some are decomposers and help with
the environment
How are they unique?
• Mollusks bodies are all very soft but have
many ways of protecting themselves from
predators
• Sea slugs avoid predation by leaving a bad
taste in predators mouth
• The mollusks in the class bivalvia have two
shells connected by a flexible hinge that
clamp close
• Octopuses and squids emit clouds of dark
colored ink to get away from predators
Describe the mollusks body plan
• All mollusks have a similar body plan
• Usually include:
–
–
–
–
Foot
Gut
Mantle
Shell
The Foot
• Soft
• Muscular
• Structure that usually contains the
mouth
The Gut
• The gut is the mollusks digestive
tract
• Digests its food
• By the stomach
The Mantle
• Layer of tissue that surrounds its
body
• Thin
• Delicate
The Shell
• Formed by glands in the mantle
• Protect the mollusk
• Not all mollusks have one
• Some are outside some are internal
The Radula
• A feeding structure
• Found in the mollusks
mouth mouth
• Uses the radula to
scrape off bits of plant
or animal matter that
the animal uses for
food.
The Mollusks Body
• The mollusks body is really soft and a
lot do not have a skeleton
• Some have a shell on the outside for
support and protection
• Mollusks such as the Squid have an
internal shell throughout their body
How do they get oxygen?
• Octopus and squid breath through their
gills
• Snails mantle cavity has a hole under
the shell that sucks in oxygen
How do they get rid of Carbon
Dioxide?
• The breathing chamber in the mollusk is
lined with blood vessels. Blood in the
vessels can get rid of carbon dioxide
and pick up oxygen. The heart pumps
the blood to every cell in the body. The
cells take oxygen from the blood and
give up the waste gas carbon dioxide.
Reproduction
• Some swarm together to breed, some
seek partners, and few fertilize
themselves
• Some are immobile such as oysters and
mussels can produce both female and
male sex cells in different periods of its
life. They will shed their sex cells and
the tides will take them to where the
sperm meets the egg and fertilizes it.
What is their nervous system
like?
• They have a relatively complex nervous
system
• Varies with the species
• Octopuses are thought to be among
most intelligent of all invertebrates
Do they have a specific sensory
structures?
• Sensory organs are contained in the
head
• Some have very advanced sensory
structures
Which mollusks have advanced
sensory organs?
• Clams have poorly developed sensory
structures
• Octopus have advanced sensory
structures
How does having advanced
sensory organs benefit them?
• If these animals have more advanced
sensory organs then they can find their
prey and scope them out easier. Also, if
they are the prey, then they could smell
or see predators coming and escape
from them.
Open Circulatory System
• Blood doesn’t circulate entirely within
vessels
• Collected from gills
• Pumped through the heart
• Released directly into spaces in the
tissues
• Returns to gills
Closed Circulatory System
• Closed circulatory systems have the
blood closed at all times within vessels
of different size and wall thickness
• In this type of system, blood is pumped
by a heart through vessels, and does not
normally fill body cavities
What type of circulatory system
do they have?
• Most have an open circulatory system
• The Cephalopods are the group that
have a closed circulatory system
What is their excretory system
like?
• The excretory functions are carried out
by a pair of nephridia
– Nephridia are tubular structures that collects
fluids from the coelom and exchange salts and
other substances with body tissues as the fluid
passes along the tubules for excretion
• The nephridia empty into the mantle
cavity
How do they digest their
food?
• They have a complete and ciliated
digestive system
– Mouth
– Anus
– Complex stomach (varies with diet)
• Food taken up by cells lining the
digestive glands arising from the
stomach, then to the blood
How do they digest their
food?
• Undigested materials are compressed
and packaged
• Discharged through the anus into
mantle cavity
• Carried away by currents in water
Squids and Giant Squids
Sea Slugs
Clams
Oysters
Mussels
Scallops
Octopus
Snails
Works Cited
• Brusca, Richard C; and Gary J. Brusca. “Phylum Mollusea.”
Invertebrates. 2nd ed. 2003
• Gilpin, Daniel. “Mollusks.” Animal Kingdom Classification; Snails,
Shellfish, and Other Mollusks. 2006.
• Miller, Kenneth R., and Joseph Levin. “Animals: Invertebrates.”
Biology The Living Science. 1998
• "Mollusk." Student's Encyclopedia. 2009. Britannica Student
Encyclopedia. 7 April 2009.
<http://student.britannica.com/comptons/article
204814/mollusk>
Works Cited
• Phylum Mollusca: Mollusks. Helena Curtis and N. Sue Barnes.
WORTH
PUBLISHERS, INC. 1 April 2009.
http://www.infusion.allconet.org/webquest/invertebrates.h
tml
• "How Smart Is the Octopus? Bright Enough to Do the Moving
Rock-Trick." Kitty Mowmow's Animal Expo. 9 Apr. 2009
<http://www.kittymowmow.com/2008/06/27/how-smart-istheoctopus-bright-enough-to-do-the-moving-rocktrick/>.
• "Palau 2004: My Photo Gallery." Palau 2004. 10 Apr. 2009
<http://www.seerious.com/Palau2004.htm>. “Mollusks and
•
Echinoderms.” 2009. 8 April 2009.
<http://74.125.95.132/search?q=cache:TZ4VBK217egJ:fair
mont.k1>