Phylum Cnidaria Cnidos =

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Phylum CnidariaCnidos Stinging Needle
www.onacd.ca
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BC jellyfish and sea pen
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Coral

• Water temperature must be at least
• 25 degrees Celsius to survive!!!
• The Great Barrier Reef in Australia can be seen
  from outer space!
• The remains of billions of individual creatures!
• Some coral reefs are 300 metres thick
• Some coral reefs are 25000 years old!

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Coral

• Water temperature must be at least
• 25 degrees Celsius to survive!!!
• The Great Barrier Reef in Australia can be seen
  from outer space!
• The remains of billions of individual creatures!
• Some coral reefs are 300 metres thick
• Some coral reefs are 25000 years old!

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OUCH!
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Stings from a Portuguese Man-of-War
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4 Classes of Phylum Cnidaria
HYDROZOA Obelia, Hydra (above), Portuguese Man
O War
SCHYPHOZOA - Jellyfish
CUBOZOA box jellies (sea wasps)
ANTHOZOA anemones (above), corals, sea fans
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Characteristics - Phylum Cnidaria

• Acoelomates therefore do not possess any true
  body systems or organs.
• 2 germ layers include ectoderm (protection),
  endoderm (inner lining)
• and mesoglea (not a germ layer-its the jelly!!!)
• Radial symmetry

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Characteristics - Phylum Cnidaria

• Tentacles
• Capturing food with stinging cells
  (cellcnidocyte with nematocysts)
• Transportation
• Possess a Gastrovascular Cavity (GVC)
• Primitive Nervous System (nerve net)
• Hermaphroditic can reproduce sexually (do not
  self fertilize) or asexually by regeneration or
  budding
• Have a motile (medusa) and a sessile (polyp)
  stage in their lives

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NERVE NET

• The first animals to have nerve cells.
• The nerves form a nerve net
• There is no brain
• There is no cephalization (a bunching of nerve
  cells to form a brain)

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2 Body Types

• Polyp
• Medusa

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Gastrovascular Cavity (GVC)

• digestion, circulation, respiration and
  excretion.
• Cons
• only one opening.. The mouth is the anus..
• Body systems - not separated or specialized

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GVC

• Digestion glands release enzymes into body
  cavity
• Circulation via currents generated by body
  movements flagella on endodermal cells
• Respiration Excretion via diffusion because
  ectoderm endoderm are in direct contact with
  the water

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Cnidocyte with the Nematocyst
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The stinging cells Nematocysts

• Function to ward off predators and attack prey
• Location end of tentacles
• Special cells called cnidocytes
• Contain organelle called nematocyst
• Produce a toxin
• Action Releases a barbed needle that penetrates
  the flesh and injects toxins when stimulated

A discharged nematocyst
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Life cycle of a typical Jellyfish
1-10 exhibit the formation of the polyp life
form. 11 shows the polyp undergoing asexual
reproduction in the form of budding. The top of
the polyp breaks off and goes on to form the
medusa stage of the jellyfishs life. (if this
was an anemone the polyp would settle on the
ocean floor and become a new polyp. See picture
of brooding anemone on next slide) 12-14 shows
the formation of the adult medusa The medusa will
then go on to produce and release egg and sperm
into the water. The eggs will be cross
fertilized by the sperm of another medusa and
eventually develop into a new polyp
This alternating between two life forms is termed
ALTERNATION OF GENERATIONS
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Brooding Anemones - very common Other polyps
form off existing polyps, break off and then
settle on the ocean floor Asexual reproduction!
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Ecological Importance of Cnidarians

• Filter and clean the water
• Coral die as water temperature increases or
  decreases.
• Death of coral often precedes death of entire
  ecosystems

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Symbiotic relationships of cnidarians

• Coral a colony of polyps in symbiosis with
  algae
• Clownfish and anemone

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Benefit to clownfish stinging cells do not harm
the clownfish, but make the fish toxic to other
fishprovide protection and shelter Benefit to
anemone clownfish clean the anemone
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Killer Cnidarians

• The Portuguese Man O War
• a colony of specialized polyps and medusas (not a
  single jellyfish)
• sting - causes excruciating pain and sometimes
  death
• Named for its air bladder which looks like the
  sails of a Portuguese fighting ship
• Super cool fact Loggerhead turtles are actually
  immune to their toxins and feed on the Portuguese
  Man O War

Portuguese Man O War Physalia physalis
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A common sign to observe near Australian Beaches
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• Box Jellyfish
• Possess the most deadly venom (toxins) in the
  animal kingdom which cause anaphylaxis shock and
  death
• In Nov. April they are abundant in Australian
  waters but it is not known where they go for the
  winter
• Through ultrasonic tagging it has been found that
  they sleep on the ocean floor between 3pm and
  dawn to conserve energy and avoid predators
• Possess 22 very simple light sensing eyes as well
  as a more developed eye 0.1 mm across

Box Jellyfish Chironex flecker This jellyfish
has had an ultrasonic tag attached (very
carefully!) to it in order to help learn more
about the migration patterns of these cnidarians
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Jelly FISH OUT OF WATER
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• http//ca.youtube.com/watch?vFm3EmkWMeHY (part
  1 cnidaria)
• http//ca.youtube.com/watch?vQvUZJh9MHt8 (part
  2 cnidaria)
• http//ca.youtube.com/watch?v6zJiBc_N1Zk
  (nematocyst firing)
• http//ca.youtube.com/watch?vDm98n3908QM
  (swimming anemone)
• http//ca.youtube.com/watch?v_jNwWQtLeY4
  (fighting anemone)
• http//ca.youtube.com/watch?vJoMCTvRkvxo
  (national geographic jellyfish)
• http//ca.youtube.com/watch?vJoMCTvRkvxo(anemone/
  clownfish partnership)
• http//www.youtube.com/watch?vgrTN7BIbzfY comb
  jellyfish