Chapter 28 Simple Invertebrates

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Chapter 28 Simple Invertebrates

• Sponges- the simplest organisms

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Plan for notes

• As we discuss each aspect of simple
  invertebrates, complete the spreadsheet you have
  on your desk titled Simple Invertebrates
• Your job is to determine what information goes
  where on the spreadsheet, I am not going to tell
  you so dont shout out questions- THINK, READ,
  LISTEN before you speak!
• If you do not finish the spreadsheet as we are
  discussing it, look in your textbook pages
  617-636 for answers for homework.

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Addition to notes

• Write page 617-636 at top of page to help with
  homework if you dont finish.
• Please add under the Animal heading the word
• EXAMPLES

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General Features of Sponges

• They are animals but they completely lack
  symmetry (asymmetry) and are just a mass of
  specialized cells
• Sort of like the sand-man in SpiderMan3- if you
  put the cells through a mesh sieve they would
  find each other and get back together again
  making a new sponge.

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General Features of a Sponge Body coverings,
Locomotion

• OSTIA - small pores all over the sponge through
  which water enters.
• OSCULA - larger openings through which water
  exits.
• SESSILE - they dont move, they attach
  themselves to submerged surface and stay there
  for their lives. (locomotion)
• CHOANOCYTES - collar cells that line the
  internal cavity of a sponge. Have flagella on
  them that beats water (and food) into the cavity.
• AMOEBOCYTES - sponge cells that supply the rest
  of the sponges cell with nutrients and carrying
  away wastes.

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Sponge Diversity Body Covering

• Brillantly colored sponges abound in warm,
  shallow sea waters.
• Some may contain hundreds of folds that are
  visible as fingerlike projections.
• The folds increase the sponges size and surface
  area.

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Sponges people like them.
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Sponge Skeletons

• Does not have a fixed skeleton like a human
• Composed of SPICLULES tiny needles composed of
  silica or calcium carbonate.
• Some sponges have SPONGIN a resilient, flexible
  protein fiber that provides support for the
  sponge.

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Sponges simple but important
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Reproduction

• Sponges can reproduce asexually
• Can regenerate when cut into pieces each bit of
  sponge can become a new sponge.
• In freshwater sponges, if life gets rough, they
  form GEMMULES clusters of amoebocytes encased
  in protective coats. When conditions improve,
  they grow.

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Gemmules how freshwater sponges make it through
the winter.
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Looks sort of gross, but it is just gemmules
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Can reproduce sexually too.

• Most sponges are hermaphrodites. Since eggs and
  sperm are produced at different times,
  self-fertilization is avoided.
• In most species of sponges, fertilization occurs
  sperm from one sponge enter another sponge
  through pores.
• Collar cells pass sperm into mesohyl, where egg
  cells are.
• Fertilized eggs develop into larva and leave
  sponge
• After brief free-swimming stage, the larvae
  attach themselves to an object and develop into
  new sponges.

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Thats all for Sponges!
If you were not able to get the 6 columns of
information, the movie on Sponges will also give
you information, just listen!!!
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Cnidarians

• (nih DAIRians)

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Two Body Forms You may fill in these notes in
the Cnidarians row

• Medusa free floating have nerves and muscle
  tissue (hint for locomotion), jellylike and often
  umbrella shaped. Radial symmetry
• Polyp- tubelike, sessile,(another hint for
  locomotion) often attached to a rock or some
  other substance. Radial symmetry
• Many cnidarians exist only as medusas, while
  others exist only as polyps. Others alternate
  between the two.

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Cnidocytes what makes cnidarians sting! Example
of body coverings

• Cnidocytes are stinging cells located on the
  tentacles of the gastrovascular cavity of
  cnidarians.
• Nematocyst Harpoons inside the cnidocytes used
  for defense and to spear prey. Some have deadly
  toxins, while others contain chemicals that stun.
  

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The Three Classes of Cnidarians and examples of
each

• Hydrozoans most primitive, polyp and medusa
  stages, freshwater and marine, many individuals
  (medusa and polyps) live together in a colony
  example Portuguese man-of-war,
• Scyphozoans true jellyfish, active predators,
  both medusa and polyp stages, box jellies
• Anthozoans exist only as polyps, examples sea
  anemones and corals

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Marine Hydrozoa

• Much more complicated. Colonies incorporate both
  medusa and polyps together
• Example Physalia, Portugese Man of War
• Gas filled polyp helps it float, other medusa and
  polyps help it reproduce and eat.
• A single colony can contain 1,000 individual
  medusas and polyps.

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Fertilization and Reproduction in Hydrozoans

• Asexually by budding
• Buds turn into polyps
• Polyps turn into medusa
• Fertilization
• Medusa male and female release sperm and eggs
• Produce zygotes that develop into free swimming,
  ciliated larvae called planulae.
• Planulae eventually settle on ocean bottom and
  develop into new polyps.

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Hydrozoans

• Body coverings Polyps form calcium carbonate
  skeletons

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2nd Class of Cnidarians- Scyphozoans

• True jellyfish(example)
• Active predators, ensnare and sting prey with
  tentacles (body coverings)
• Live as both polyps and medusas (skeletal
  structure)

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2nd Class of Cnidarians- Scyphozoans

• Body symmetry Radial

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2nd Class of Cnidarians- Scyphozoans

• Locomotion Free swimming medusa, sessile polyp
  stage

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2nd Class of Scyphozoans Reproduction and
Fertilization

• Most medusas reproduce sexually
• Some have polyp stage reproduce asexually
• Medusa release sperm and eggs into water,
  fertilized zygote forms polyp eventually medusa

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3rd Class of Cnidarians anthozoans

• Largest class of cnidarians
• Exist only as polyps (skeletal structure)
• Thick stalklike body topped by tentacles
  (skeletal structure) tentacles (body covering)
• Examples Sea anemones, corals (skeletal
  structure of corals hard outer covering of
  calcium carbonate)

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Fertilization and Reproduction of anthozoans

• Fertilization sperm and eggs released into
  ocean, where fertilization occurs
• Reproduction asexually form buds, also
  reproduce sexually by the above method of
  releasing sperm and eggs into ocean

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Examples of Anthozoans Sea Anemones
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Examples of anthozoans CoralsRadially symmetric
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Final simple invertebrates Flatworms and
Roundworms

• Flatworm examples marine, tapeworms, flukes
• Skeletal structure acoelomate, flat ribbonlike,
• Body symmetry bilaterally symmetric meaning
  they have left and right halves that mirror each
  other

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Flatworms

• Some flatworms reproduce asexually by tearing in
  two, each half regenerates
• Some reproduce sexually hermaphrodites that
  fertilize each others eggs.
• Fertilization occurs when sperm and egg form
  zygote. Zygotes released in clusters in a
  protective capsule

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Examples of Flatworms Marine Flatworms
Locomotion ribbonlike, undulating
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Examples of Flatworms Tapeworms
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Examples of Roundworms vinegar eels, parasitic
roundworms, pinworms, hookworms, heartworms (in
dogs), and ascaris (intestinal roundworm). 
Humans can contract parasitic worms by eating
under cooked beef or pork
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Roundworms

• Skeletal structure pseudocoelom have one way gut
• Fertilization Internal in the female
• Reproduction Reproduction is usually sexual.
  Males are usually smaller than females (often
  much smaller) and often have a characteristically
  bent tail

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Roundworms cause elephantitis
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Roundworms (picture is of a hookworm)

• Body coverings of both flatworms and roundworms
  flexible thick outer covering and cuticle
  (tegument)

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Roundworm Locomotion

• Locomotion wriggling or thrashing, muscles on
  one side contracting, while the other side expands

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If you have not completed all the blanks on the
spreadsheet, find the answers in your textbook
for homework, pages 617-636We are now going to
watch a video on Sponges, you will take a quiz as
you are watching the video- pass this in at the
end of the period.