Transcript Document 7188577

General Zoology Unit Two
Objective Eighteen
Definitions
Diploblastic – having two germ layers from
which tissues and structures arise
Ectoderm – outer germ layer that gives
rise to tissues and structures that cover the
outside
Endoderm – inner germ layer that gives
rise to tissues and structures that cover the
inside
Mesoglea – jelly-like substance found
between the inner and outer layers
General Zoology Unit Two
Objective Nineteen
Eukaryotic, eumetazoans
Diploblastic
Have true tissues, but no organs
All are marine
Radially symmetrical (no cephalization)
Polymorphic – two forms (polyp & medusa)
Cnidocytes – stinging cells
Have a nerve net
Polyps are sessile, while medusae can move
Asexual and sexual reproduction
General Zoology Unit Two
Objective Twenty
Cnidarian Taxonomy
Kingdom - Animalia
Phylum - Cnidaria
Class – Hydrozoa
Ex. – Physalia, Obelia, Hydra, Gonionemus
Class – Scyphozoa (true jellyfish)
Ex. – Aurelia, Cassiopeia
Class – Cubozoa
Ex. – Carybdea
Class – Anthozoa
Ex. – Metridium, Gorgonia, Tubipora
General Zoology Unit Two
Objective Twenty One
Cnidarian Polymorphism
Polyp Anatomy
Gonionemus
Aurelia
Cnidocy
te
Anatom
y
General Zoology Unit Two
Objective Twenty Two
Most are marine and colonial
in form
Most forms exhibit
alternation of generations
between asexual polyps and
sexual medusae, but some
have only one or the other
form
Obelia
Hydra
Physalia
Referred to a the true
jellyfish
All are solitary
Polyp stage is much reduced
or absent
Main body is cup shaped
Aurelia
All are relatively small in size
All are solitary
Polyp stage is much reduced
Main body is cube shaped
Carybdea
Polyp form predominant, no
medusa stage
Some are solitary, while
others are colonial
Many form zooxanthellae
relationship with algae
Most ecologically important
group due to reef building
Metridium
Gorgonia
Tubipora
General Zoology Unit Two
Objective Twenty Three
Alternation of
generations
Planula
Budding
Alternation of generations
Planula
Budding