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Phylum Coelenterata
(phylum Cnidaria)
Zoology
May 25, 2017
Mrs. McCarthy
I.
Classification
A. 2 phylum names
1. Coelenterata – hollow gut
2. Cnidaria – nettle
II.
Basic Characteristics
A.
Tissue level
1.
Sac – like body with 3 layers
a.
epidermis
b.
mesoglea
c.
gastrodermis
2.
Gastrovascular cavity –
hollow internal body cavity
B.
Nervous system
1.
Nerve net – nerves evenly
spaced
2.
Statocysts – structures for
balance (hollow ball of cells
with a grain of sand)
3.
Ocelli – light sensitive
structure
C.
Tentacles
1.
Capture food
2.
Cnidoblast/cnidocyte – cell
that contains the stinging
organelle
3.
Nematocyst – stinging organelle
a.
capsule with coiled
“harpoon” containing
toxins
b.
Operculum – flap that
holds the coil inside
c.
Stimulated by touch and
chemicals
D.
Habitat
1. Mostly shallow, marine
2. Pelagic – open water
3. Benthic – bottom dweller
4. Symbiosis
a. on other animal’s shells
b. with algae that provide
energy from
photosynthesis
E.
Reproduction
1. Polymorphism “many
shapes”
2. Polyp – sessile, tentacles up
3. Medusa – floating, tentacles
down
4. Many alternate forms
5. Asexual reproduction
a. budding
b. regeneration
6. Sexual reproduction
a. mostly dioecious
III. Class Hydrozoa – “water animal”
A. Hydra – freshwater polyp
1. Basal disk at the bottom
2. 6 – 10 tentacles
3. Hypostome – raised area
around the mouth
4. Eat small crustaceans,
insect larvae, tiny worms
5.
Locomotion
a.
b.
c.
d.
sliding along on basal disk
inch – worm
floating with gas bubble
epitheliomuscular cells for
covering and contraction
6.
Reproduction
a. asexual
b. sexual
1. Sperm released
into water
2. Eggs fertilized in
female
3. Ciliated larva is
released, develops
into adult
B.
Hydroid colonies
1. genus Obelia – polymorphic
life cycle
C.
Portuguese Man-O-War
1. genus Physalia
2. Floating colony of
individual animals
3. Pneumatophore – the float
on the surface
IV. Class Scyphozoa – “cup animal”
A. genus Aurelia – common
jellyfish
B. Thick mesoglea
C. Tentacles can be up to 70 m
D. Dioecious, polymorphic life
cycle
V. Class Cubozoa – “cube animal”
A. Square shaped medusa
B. Australian box jelly – one of the
most poisonous animals in the
world
Chironex fleckeri (the sea wasp) is the deadliest
jellyfish in the ocean.
Box Jelly sting scars
• box jelly link
• Two concepts are key to treating box jellyfish stings. One is to prevent
firing of any undischarged nematocysts remaining on the skin, thus
preventing the injury from getting worse. The second is to treat the
symptoms and pain caused by already-fired nematocysts. The
following first aid treatment, based on current Australian research, is
recommended for the stings of all species of box jellyfish:
• Immediately flood the area with household vinegar to keep
undischarged nematocysts from firing. This does not relieve pain, but
prevents additional stings.
• Never rub the area with sand or anything else.
• Irrigate exposed eyes with copious amounts of room temperature tap
water for at least 15 minutes. If vision blurs, or the eyes continue to
tear, hurt, swell, or are light sensitive after irrigating, see a doctor.
• Pluck off any vinegar-soaked tentacles with a stick or other tool.
• If the victim has shortness of breath, weakness, muscle cramps,
palpitations or any other generalized symptoms, take them to an
emergency room.
• For pain relief, apply ice packs. If pain becomes unbearable, go to an
emergency room. No studies support applying heat to box jellyfish
stings.
• Contradictory studies exist on the effectiveness of meat
tenderizer, baking soda, papaya, or commercial sprays
(containing aluminum sulfate and detergents) on
nematocyst stings. These substances may cause further
damage. Some kinds of meat tenderizer, for instance, can
cause skin peeling. In one U.S. fatality from the box
jellyfish, Chiropsalmus quadrumanus, rescuers placed
meat tenderizer almost immediately on the affected arm.
The child was soon comatose and later died.
• Alcohol and human urine are common nematocyst
remedies, but both can be harmful. An Australian study
reports that both alcohol and urine caused massive
discharge of box jellyfish nematocysts.
VI. Class Anthozoa – “flower animal”
A. Large gastrovascular cavity
separated by mesenteries to
increase surface area for
digestion
B. genus Metridium – sea
anemone
1. Live symbiotically with
algae, crabs, and clown fish
3. Some are protandrous
C.
Corals are colonial
1.
True corals have secreted calcareous
cups
2.
Thorny corals are branched
3.
Tube anemones
4.
Hermatypic corals – reef
building
a.
fringing reef – close to
land mass with a very
narrow lagoon
b.
barrier reef – parallel to
shore with a wide, deep
lagoon
c.
atoll – encircles a lagoon,
usually on a submerged
volcano
Classification
Kingdom Animalia
Phylum Coelenterata (Cnidaria)
Class Hydrozoa
Hydra
Genus Obelia
Genus Physalia Portuguese Man-o-war
Class Scyphozoa
Genus Aurelia Common jellyfish
Class Cubozoa
Australian Box Jellyfish
Class Anthozoa
Genus Metridium Sea anemone
Corals