Chapter%207:%20CNIDARIANS:

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Chapter 7 CNIDARIANS

• Jellies, Corals, and Anemones

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Cnidarians

• Cnidarians are named because of the stinging
  cells they possess - cnidocytes
• Cnidocytes produce organelles called nematocysts
  that actually sting the prey

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Cnidarians

• Cnidarians are radially symmetrical.
• Look the same from all sides and have no head,
  front, or back

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• Cnidarians have 2 ends
• Oral Surface
• Aboral Surface

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Anatomy Physiology

• 2 tissue layers
• Intermediate non-living layer
• Serves as support system
• Single opening (mouth/anus) and no head

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Cnidarians

• Cnidarians occur in 2 basic forms.
• Polyp form attaches to the bottom sediments, the
  mouth opens upwardly and is surrounded by a ring
  of tentacles
• Medusa form free-floating stage - commonly known
  as a jellyfish

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Cnidarian Classes

• 3 classes of cnidarians
• Hydrozoans
• Scyphozoans
• Anthozoans

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Cnidarian Hydrozoan

• Hydrozoans
• colonial organisms
• not true jellyfish.
• Can be drifting polyps or siphonophores

Siphonophores like the Portuguese man-of-war are
drifting colonies of polyps
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Cnidarian Scyphozoan

• Scyphozoan
• true jellyfish
• have limited swimming abilities, so they depend
  on the currents
• Spend most of their life as a medusa

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Schyphozoan - cannon ball jelly
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Scyphozoan - moon jelly
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Scyphozoan - Sea Nettle
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Scyphozoan - Upside-down jelly
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Scyphozoan - Lions Mane
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Anthozoans

• Includes - sea anemones, corals, sea fans, sea
  pens, and sea pansies
• EXCLUSIVELY polyp form
• They can be very colorful - look like underwater
  flowers
• Most complex cnidarian

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Anthozoan - continued

• They have strong muscles that allow them to
  extend and retract their tentacles - for feeding
  and avoidance of danger
• Often are symbiotic
• When two organisms create a union in which each
  is benefited by the other

Over time the clownfish becomes immune to the
sting of sea anemones, then uses the anemone for
protection
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Anthozoans - Corals

• Two types - hard and soft corals
• Hard corals secrete a calcium carbonate skeleton
  - which remains after death
• Soft corals do not produce the rigid skeleton and
  look more like plants than animals - sea fans and
  sea pens are two examples

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Polyp Anatomy
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Coral Nutrition

• Zooxanthellae provide nourishment for the coral
  through photosynthesis
• Coral has an immense surface area for feeding
  (the entire reef)

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Bartholomea annulata Corkscrew Anemone

• Description thin, droopy tentacles that spiral
• Distribution Florida, Bahamas, Caribbean

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Gorgonia ventalina Common Sea Fan

• Description
• single plane and fan shaped
• Purple, yellow, or brown
• Distribution
• Florida Keys near coral reefs

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Pennatulacea Common Sea Pen

• Description
• Resemble quill pens, will glow when touched
• Distribution
• Shallow and deep water from polar waters to
  tropics

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Renilla Sea Pansy

• Description
• Flattened, kidney-shaped
• Distribution
• Pacific and Atlantic coasts of North America

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Montastrea annularis Boulder Start Coral

• Description
• Form dome-like tops
• Large mounds
• Shades of green, brown, yellow, and gray
• Distribution
• Western Atlantic Ocean

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Sponge and Cnidarian Video

• http//youtu.be/DuQcmpHZ9tQ

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Coral Reefs

• Economy
• Tourism
• Fishing
• Research
• Types
• Fringing
• Barrier
• Atoll

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Ecology

• Marine and Freshwater (Hydrozoa)
• All oceans, all depths
• Symbiants
• Shelter and food

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Phylum Ctenophora (comb jellies)

• Have eight rows of cilia on their outer body -
  used in locomotion
• They do not have stinging cells!!!
• They catch food by trapping it a sticky coating
  on their cilia or sucking in mouthfuls of water

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COMB JELLY
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