Download KINGDOM ANIMALIA Phylum Cnidaria

KINGDOM ANIMALIA
Phylum Cnidaria
Phylum Cnidaria
The phylum name comes from
Cnidaria, the Greek word for nettle,
a plant that has stinging hairs.
Members of the
Phylum Cnidaria
…exhibit radial or biradial
symmetry.
…are all aquatic (typically marine,
but some freshwater).
…are sessile, free-floating, or weak
swimming.
…have a tissue-level organization.
…have a primitive nervous system.
…have stinging cells.
Question
Which of the following characteristics
sets the members of the phylum
Cnidaria apart from all other animals?
A. They are all aquatic.
B. They have stinging cells.
C. They are all multicellular.
D. They are sessile as adults.
General Organization
Cnidarian bodies are organized around the
gastrovascular cavity, where digestion takes
place.
Two layers of cells: gastrodermis (lining the
digestive tract) and epidermis (outer layer)
Mesoglea: jelly substance in between the two
cell layers.
Question
In a cnidarian, the jelly substance
in between the two cell layers is
called
A.
B.
C.
D.
mesoglea
cnidoglea
epidermis
gastrodermis
Reproduction
Sexual reproduction: gametes are
shed directly into the water.
Asexual reproduction: usually by
budding, some by fission.
Question
Cnidarians reproduce in all of the
following ways, EXCEPT
A.
B.
C.
D.
Asexual fission
Asexual budding
Sexual regeneration
Sexual reproduction involving egg
and sperm
Life Cycles:
Polyp and Medusa
Cnidarians generally alternate
between sessile polyps that
reproduce asexually and swimming
medusae that reproduce sexually.
One of these stages is missing in
many forms.
Question
True or False:
This picture represents
the medusa body plan
of a cnidarian.
Stinging Tentacles
The tentacles of all cnidarians
produce nematocysts, organelles
that can discharge threads to
entangle, penetrate, or poison prey.
The tentacles are composed of cells
called cnidocytes, which contain the
nematocysts.
Cnidocyte
Question
In a cnidarian, the cnidocytes
are used for
A. swimming
B. digesting food
C. paralyzing prey
D. sensing predators
Feeding and Digestion
Cnidarians prey on a variety of
appropriate-sized prey.
Prey is normally drawn into the
gastrovascular cavity by the
tentacles.
Here, gland cells discharge enzymes
onto the food.
Question
Where does digestion take
place for cnidarians?
A.
B.
C.
D.
In the tentacles
In the epidermis
Outside the body
In the gastrovascular cavity
Four Important
Cnidarian Classes
1. Class Hydrozoa
Mostly marine
Alteration of generation (polyp
and medusa stages) is usually
exhibited
Includes hydroids, fire corals, and
Portugese man-of-war
Hydrozoan: Hydra
Portuguese Man of War
Four Important
Cnidarian Classes
2. Class Scyphozoa
Dominant stage is the medusa
Polyp is absent or reduced
Cup-shaped umbrellas
Includes true jellyfish
Scyphozoa: Aurelia labiata
Four Important
Cnidarian Classes
3. Class Cubozoa
Like jellyfishes, but they have
cubical umbrellas.
Some may deliver fatal stings.
Includes the box jelly, one of the
10 most venomous organisms on
earth.
Cubozoans
Four Important
Cnidarian Classes
4. Class Anthozoa
Polyps with a flowerlike appearance
No medusa stage
All marine, found all over the world
Includes sea anemones, corals, sea
fans, and sea whips.
Anthozoans: Corals
Anthozoans: Anemones
Economic Importance
Reef-building corals
provide habitat for fish and
other animals that are
important as food sources
for humans.
Coral reefs are tourist
attractions and coral rocks
are used as building
materials and jewelry.