Unit 8 Chapter 26 Sponges, Cnidarians, Flatworms, and Roundworms

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Unit 8Chapter 26Sponges, Cnidarians, Flatworms,
and Roundworms
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What is a Sponge?

• Phylum Porifera (pore-bearing)
• Sponges are aquatic, sessile, asymmetrical
  invertebrates

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What is a Sponge?

• Sponges are filter-feeders
• Feed by filtering small particles from the water
  that passes through its pores

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What is a Sponge?

• Sponges are soft-bodied and may contain sharp,
  hard spicules for support defense
• Others may contain spongin, a soft, fibrous
  material

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What is a Sponge?

• Hermaphrodites, producing both eggs
  sperm
• A few have external fertilization
  (occurring outside the animals body)
• Most have internal fertilization (eggs sperm
  meet within the animals body)

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What is a Cnidarian?

• Radially symmetrical, aquatic invertebrates
• Ex Jellyfish, coral, hydra, sea anemones

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What is a Cnidarian?

• Cnidarians body is only two cell layers
• Cnidarians sting their prey with cells called
  nematocysts, located on their tentacles

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What is a Cnidarian?

• Cnidarians have two basic body shapes
• Medusa
  bell-shaped,
  free-swimming
• Polyp
  tube-shaped,
  sessile

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What is a Cnidarian?

• Many Cnidarians live in colonies Ex Portuguese
  man-of-war
• Some Cnidarians build reefs Ex Coral

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What is a Flatworm?

• Phylum Platyhelminthes
• Acoelomates, with three cell layers
• Marine, freshwater, moist land habitats

A Fluke
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What is a Flatworm?

• Flatworms may be free-living, like the
  fresh-water Planarian
• Planaria have a simple nervous system, including
  eyespots for light detection

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What is a Flatworm?

• Planaria have remarkable powers of regeneration,
  the ability to replace missing parts

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What is a Flatworm?

• Flatworms may be parasitic, like the fluke
  tapeworm
• Tapeworms attach to hosts intestines with their
  scolex (head) and produce many proglottids (body
  segments)

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What is a Flatworm?

• Tapeworms have a complex life history, that may
  include several hosts

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What is a Roundworm?

• Phylum Nematoda
• Pseudocoelomates, with two body openings
• Free-living forms are important decomposers in
  the soil

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What is a Roundworm?

• Many roundworms are parasites, i.e. pinworms,
  hookworms, heartworms
• Trichinosis is a disease caused by a roundworm
  found in improperly cooked pork

Heartworms in a Dogs heart