Phylum Cnidaria

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Phylum Cnidaria

• The Stinging Celled animals
• Kingdom Animalia
• Approx. 11,000 species

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Cnidarian Habitat

• All live in water -aquatic
• Most live in saltwater - marine
• Few are freshwater ex. Hydra

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Cnidarian Movement

• Some can move
• (motile)
• Some cannot move
• (non-motile)

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General Cnidarian Info

• All are consumers
• They get food with stinging cells
• Cnidocytes
• Cnidocytes cover the tentacles only
• Prey is captured in tentacles stung to death
• When prey is dead it is stuffed into the gut

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Diagram of Nematocyst
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General Cnidarian Info

• What do they eat?
• Depends on the size
• Fish, worms, microorganisms, etc
• Cnidarians are Chunk Feeders
• Not filter feeders like sponges

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Body Forms

• Polyp tube with tentacles
  pointing up
• Often sessile (attached)
• Medusa umbrella with
• tentacles hanging down
• Often float or use jet propulsion

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Symmetry

• Radial symmetry (wheel-like body plan)
• No head/tail or front/back

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Cnidarian Body Structure

• Inner Wall (Endoderm)
• 3 kinds of cells
• Cells that make digestive enzymes
• Cells with flagella to circulate fresh water from
  outside
• Cells that contain partially digested food which
  is absorbed into the body
• Outer wall - Ectoderm skin layer for protection
• Middle Jelly layer - mesoglea
• contains nerve net
• Hollow gut Gastrovascular cavity

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Cnidarian Reproduction

• Reproduction sexual or asexual
• Sexual two parents - Sperm Egg
• Asexual one parent - budding

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Coelenterate Examples

• Jellyfish, Portuguese Man-of-War, Sea Anemone,
  Coral, Hydra

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Jellyfish

• Named for thick layer of mesoglea
• Body form Medusa
• Size from a few mm to a few meters
• Dangerous Examples
• Sea Wasp Jellyfish
• Box Jellyfish

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Jellyfish Pictures
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Portuguese Man-of-War

• Looks like a floating plastic bag
• Body form Colonial
• Some polyp
• Some medusa
• Size from a few cm to over 1 meter

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Portuguese Man-of-War

• Some are dangerous to humans, possibly even deadly

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Sea Anemone

• Named for a flower
• Body form polyp
• Size from a few cm to over 1 meter
• Mostly non-motile, but some can glide slowly

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Sea Anemone

• Many species live with a clownfish this is a
  Mutualistic Relationship
• The fish gets protection
• The anemone gets food lured by the brightly
  colored fish

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Coral

• All are non-motile
• Body form Polyp
• Size rarely larger than 1 mm
• Protection build a crater of limestone around
  body

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Coral

• Coral reefs
• Largest Coral Reef
• Great Barrier Reef in Australia

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Hydra

• All live in freshwater
• Body form polyp
• Size max. ½ inch
• Move by gliding, somersaulting, floating

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Comparing Sponges Coelenterates

• Number () of Species
• Habitat
• Symmetry
• Feeding
• Reproduction
• Movement

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Comparing Sponges CoelenteratesNumber () of
Species

• Sponges
• Approx. 5,000

• Coelenterates
• Approx. 11, 000

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Comparing Sponges CoelenteratesHabitat

• Sponges
• Mostly saltwater (marine)
• Some freshwater

• Coelenterates
• Mostly saltwater (marine)
• Some freshwater

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Comparing Sponges CoelenteratesSymmetry

• Sponges
• Radial (wheel-like)

• Coelenterates
• Radial (wheel-like)

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Comparing Sponges CoelenteratesFeeding Habits

• Sponges
• Filter Feeders
• Bacteria, algae, protozoans

• Coelenterates
• Chunk Feeders
• Fish, worms, some microorganisms

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Comparing Sponges CoelenteratesReproduction

• Sponges
• Sexual sperm egg
• Asexual budding
• regeneration
• gemmules

• Coelenterates
• Sexual sperm egg
• Asexual - budding

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Comparing Sponges CoelenteratesMovement

• Sponges
• All sessile (non-motile)

• Coelenterates
• Some motile
• Some sessile