The Phylum Molluska

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The Phylum Molluska

• By Zach Lashbrook Sarah
  Briggs

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Different Types of Mollusks

• Cephalopods
• Gastropoda
• Bivalvia
• Polyplacophora

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Cephalopoda

• Octopus

• Squid

• Cuttlefish

Octopuses Squids
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Gastropoda
gastro means stomach or bellypod means foot

• Snails
• Whelks
• Periwinkles
• Abalone
• Slugs

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Bivalvia

• Clams

• Scallops

• Oysters

• Mussels

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Polyplacophora
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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

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The Habitat

• Cephalopods they are primarily free-swimming
  species
• A lot mollusks inhabit rocky seashore
  environments where their low dome-shaped shells
  are well suited.
• Some have been found at depths of 2,200 feet or
  more

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Examples of their food source

• They eat most anything
• Different Mollusks eat different things
• Snails eat leaves
• Some carnivores and eat other mollusks and worms
• Squid are predators

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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.

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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

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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

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Describe the mollusks body plan

• All mollusks have a similar body plan
• Usually include
• Foot
• Gut
• Mantle
• Shell

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The Foot

• Soft
• Muscular
• Structure that usually contains the mouth

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The Gut

• The gut is the mollusks digestive tract
• Digests its food
• By the stomach

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The Mantle

• Layer of tissue that surrounds its body
• Thin
• Delicate

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The Shell

• Formed by glands in the mantle
• Protect the mollusk
• Not all mollusks have one
• Some are outside some are internal

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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.

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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

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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

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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.

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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.

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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

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Do they have a specific sensory structures?

• Sensory organs are contained in the head
• Some have very advanced sensory structures

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Which mollusks have advanced sensory organs?

• Clams have poorly developed sensory structures
• Octopus have advanced sensory structures

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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.

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Open Circulatory System

• Blood doesnt circulate entirely within vessels
• Collected from gills
• Pumped through the heart
• Released directly into spaces in the tissues
• Returns to gills

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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

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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

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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

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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

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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

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Mollusks...
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Squids and Giant Squids
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Sea Slugs
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Clams
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Oysters
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Mussels
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Scallops
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Octopus
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Snails
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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.
  lthttp//student.britannica.com/comptons/article
  204814/molluskgt

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Works Cited

• Phylum Mollusca Mollusks. Helena Curtis and N.
  Sue Barnes. WORTH PUBLISHERS, INC. 1 April
  2009. http//www.infusion.allconet.org/webquest/i
  nvertebrates.h tml
• "How Smart Is the Octopus? Bright Enough to Do
  the Moving Rock-Trick." Kitty Mowmow's Animal
  Expo. 9 Apr. 2009 lthttp//www.kittymowmow.com/200
  8/06/27/how-smart-is- the- octopus-bright-enough-t
  o-do-the-moving-rock- trick/gt.
• "Palau 2004 My Photo Gallery." Palau 2004. 10
  Apr. 2009 lthttp//www.seerious.com/Palau2004.htmgt
  . Mollusks and
• Echinoderms. 2009. 8 April 2009.
  lthttp//74.125.95.132/search?qcacheTZ4VBK217egJ
  fair mont.k1gt