Figure 33.2 Sponges

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Figure 33.2 Sponges
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Figure 33.3 Anatomy of a sponge
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Cnidaria
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Characteristics of Cnidaria

• Basic body plan
• Armed with stinging cells called nematocysts
• Incredibly diverse in form (jellyfish, medusae
  and corals, hydroids, box jellies)
• Some cnidarians are almost totally dependent on
  single celled algae others trap prey but augment
  their diet with microscopic algae
• Life Cycle medusa free swimming/sexual
  reproduction and polyp stationary/sessile
  asexual reproduction

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Figure 33.4 Polyp and medusa forms of cnidarians
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Figure 33.5 A cnidocyte of a hydra
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Figure 33.7 The life cycle of the hydrozoan
Obelia (Layer 1)
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Figure 33.7 The life cycle of the hydrozoan
Obelia (Layer 2)
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Figure 33.7 The life cycle of the hydrozoan
Obelia (Layer 3)
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Classes of Cnidaria

• Hydrozoa
• Scyphozoa
• Anthozoa

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Hydrozoa

• Most alternate between a polyp and medusa stage
• Spend sexual lives as jellyfish
• Most are colonial sessile form/asexual
• Single organism or colony

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Figure 33.6 Cnidarians Hydrozoans (top left),
jelly (top right), sea anemone (bottom left),
coral polyps (bottom right)
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scyphozoa

• True jellyfish
• Range in size from twelve millimeters to more
  than two meters across.
• No head, no skeleton and no special organs for
  respiration or excretion water large percentage
  of body

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Figure 33.6bx Purple striped jelly, Pelagia
panopyra
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Anthozoa

• Completely lack a medusa stage live exclusively
  as polyps
• Supplement their diet by growing symbiotic algae
  in their tissues.
• Coral built great reefs, sea anemones,sea fans,
  and sea pens

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Figure 33.6dx Coral polyps
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Figure 33.6cx Sea anemones
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Physiology of Hydra

• Locomotion- ectoplasm contractions act as muscle
  tentacles-somersaulting action
• Food getting- coordinated effort of tentacles
  nematocysts (carnivore) trap/stun prey mouth
  engulfs food
• Digestion- gastrovascular cavity extracellular
  digestion (enzymes) intracellular finishes
  process
• Excretion- 2-way digestive tract, one opening
• Circulation- gastrovascular cavity cyclosis in
  cells
• Respiration-gases across cell surface
  (ectoderm/endoderm)
• Nervous system-nerve net sensory and motor,
  coordinated behavior
• Reproduction- asexual budding sexual-gametes
  with no medusa replace cells every 45 days

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Table 33.1 Classes of Phylum Cnidaria