Phylum Cnidaria - Mr. G's Educational Emporium
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Transcript Phylum Cnidaria - Mr. G's Educational Emporium
Phylum Cnidaria &
Ctenophora
Kingdom: Animalia
Phylum Cnidaria
Class Hydrozoa
Class Scyphozoa
Class Anthozoa
Phylum Ctenophora
Major Characteristics
Presence of specialized tissues
Also called Coelenterates
Comprised of sea anemones, jellyfish, corals
Have radial symmetry
Two forms polyps and medusa
Body Structure
All have radial symmetry, where similar
parts of the body are arranged and
repeated around a central axis
Radial vs. Bilateral Symmetry
Diagram A
Radial Symmetry
Two Main Body Forms - Polyp
A polyp is a sac like
stage.
Sessile or non-motile
Two Main Body Forms Medusa
A medusa is bell-like,
which is similar to an
upside down
swimming polyp
Free floating or
swimming
Polyp vs. Medusa
Some spend their life
as both at some
point or as one or the
other the entire time
Diagram B
Polyp vs. Medusa
Diagram D
Three Basic Layers:
Three Basic Layers
Ectoderm/Epidermis – outer layer that
contains the stinging cells
Endoderm/Gastrodermis – lines the gut
Mesoglea – Jelly like substance in
between the Ectoderm and Endoderm
which contains scattered cells and
collagen fibers
Exoskeleton
Coral will create a
calcium carbonate
shell in which it will
live
Body Structure
The mouth is located on the top of the polyp or underside
of the medusa
It is the only opening on the organism so is also shares
the function of being an anus
Diagram E
Body Structure
Diagram F
Tentacles
Slender finger like
structure used to
capture and handle
food
Location of
nematocysts
Nematocysts
The main
characteristic of
Cnidaria is the
presence of
nematocysts
Stinging structures
found on the
tentacles
Nematocysts
Coiled – like stinger
Spring into the prey and
releases toxin
Most not harmful to humans
because they cannot
penetrate skin
Some fatal
Nervous System
Main characteristic is the presence of a
nerve net
Nerves cross over each other, at every
connection, communication occurs
In humans millions cross over millions
and no communication occurs
Nerve Net
Diagram C
Digestive System
All cnidarians are carnivorous
Paralyzed by the nematocysts
Enzymes in gastric cavity break down
the food and nutrients are absorbed by
cells in the endoderm
Wastes are sent out the mouth/anus
Digestive System
Reproductive
Cnidarians have the
ability to reproduce
sexually and
asexually
One method that is
commonly seen is
budding
Class Anthozoa
Largest group of
Cnidarians
Stay in the polyp
stage throughout life
cycle
Solitary or colonial
Includes sea
anemones
Class Hydrozoa
Can consist of just a
FLOAT
polyp stage, just a
medusa stage, or
both
Can join together to
form complex
colonies such as the
Portuguese Man-OWar, which develop
floats
Class Scyphozoans
Medusa is the dominant life stage
Swim with rhythmic contractions of the bell,
though limited
Contain the most dangerous/fatal stings
BELL
Phylum Ctenophora
Comb Jellies
Not a member of the
Cnidarian Phylum
even though they
share similarities
Cnidaria vs. Ctenophora
Ctenophora
Have cilia at the
base of the medusa
to move
Engulf food
Do not have
nematocysts
Have an additional
layer between endo
and ecto layers
Anal pore