Download 3- Porifer and Cnidaria_AP Bio

Phyla of invertebrates include
1.Porifera
2.Cnidarian
3.Flatworms
4.Roundworms
5.Segmented worms
6.Mollusks
7.Arthropods
8.Echinoderms
•Sessile animals that lack nerves or muscles.
•However, individual cells can sense and
react to changes in the environment.
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Multicellular WITHOUT TISSUES
Heterotrophic filter feeders
No cephalization present
Acoelomates
Diploblastic-connected by noncellular mesogles
Respiration:
Occurs over the entire surface of
the organism wherever cells are in
direct contact with the environment.
Aquatic,
largely marine
provide structural support and deter predators
Body Plan
•Most are
asymmetrical
•Harder sponges have
spicules
•Softer sponges have
fibers made of a
flexible protein called
spongin.
•Modified
collagen
:Choanocytes
Sponge
Spicules
Spicules are the spiny skeleton
of sponges
–Secreted by specialized cells
called Archaeocytes
–Calcium Carbonate(CaCO4) or
Glasslike Silica (SiO2)
Feeding
•Feed by drawing water
into the body through
many pores and
extracting food particles.
•Choanocytes-specalized
cells with flagella.
Choanocytes pass the food to the
amoebocytes, which wander between
the two cell layers.
Reproduction
Asexual:
• New individuals bud from parents
• Parent sponge breaks into many
pieces (Fragmentation)
Sexual:
• Internal Fertilization
• Male releases clouds of sperm into
water, and water currents carry
sperm to female
• Some are hermaphrodites
Larvae use flagella to swim to new
location to become sessile adult
Tentacles covered with nematocysts (stinging, harpoon-like
structures that produce toxins that cause paralysis)
Have nerve cells- nerve net- that can sense the
environment.
Unlike highly organized nervous systems, this nerve net
transmits impulses in several directions at once, which
results in multiple firings of nematocysts in parts not
directly stimulated.
Can detect light through structures called ocelli.
Basic body plan-two variations: the sessile polyp
and the floating medusa.
• Polyps-adhere to the substratum by the aboral end and
extend their tentacles, waiting for prey.
• Medusas (also called
jellies) are flattened,
mouth-down versions
of polyps that move by
drifting passively and
by contracting their
bell-shaped bodies.
Animation
Digestion
• Gastrodermis
(cells that line the
gastrovascular cavity)
secretes
digestive
enzymes into the
gastrovascular
cavity.
• Food particles
then engulfed by
cells.
Sea Anemone
Jellyfish
Hydra
Respiration:
Occurs over the entire surface of the organism wherever
cells are in direct contact with the environment.
All Cnidarians have Cnidocytes
• cnidocytes on the
tentacles defend
the animal or
capture prey.
• Organelles
called cnidae
evert a thread
that can inject
poison into the
prey, or stick
to or entangle
the target.
• Cnidae called
nematocysts are
stinging capsules.
Feeding
•Paralyzes the
prey and then
pulls it through
its mouth into its
gastrovascular
cavity where
digestion takes
place.
•Waste is
excreted through
the mouth.
•Can also be filter feeders
•Some live in symbiosis with
autotrophic algae
-Cassiopeia
Cnidocytes: Stinging in Action
• Specialized Stinging
Cells called
Cnidocytes which
contain nematocyst in
tentacles
– When triggered by
touch or chemicals;
shoot harpoon like
barb into victim
– Also release toxin
Reproduction and Life Cycle
Have two life stages
Sexes are generally separate
Three types:
1) Medusa form dominates
2) Polyp form dominates
3) Solely polyp form
Classes of Phylum Cnidaria
•Scyphozoa- Jellyfish
Medusa form dominates
“Cup-Animal”
•Class Hydrozoa
•includes hydras and Portuguese manof-war (Physalia).
a. The polyp stage is dominant.
b. Portuguese man-of-war is a
colony of polyps; original polyp is a gasfilled float.
c. Other polyps specialize for
feeding or reproduction.
d. Can cause serious injury to
swimmers with a tentacle having numerous
nematocysts; each tentacle arises from the
base of each feeding polyp.
Obelia
Portuguese
man-of-war
•Anthoaoz-Sea Anemones, corals
Only a polyp stage
“Flower-Animal”
a. Sea anemones are solitary polyps 5-100 mm in height and
5-200 mm in diameter or larger.
b. Many are brightly colored and resemble flowers.
c. A thick, heavy body supports a mouth surrounded by hollow
tentacles.
d. Sea anemones feed on invertebrates and fish.
e. They attach to rocks, timbers, etc., or may be mutualistic and
attached to a hermit crab's shell.
f. Corals may be solitary; most are colonial.
g. Most live in shallow waters; accumulation of their calciumcarbonate remains builds reefs.
Anthozoa
Box Jelly fish
In order for the Clownfish to live within the tentacles of the sea anemone, it must develop immunity to the stinging cells of the
anemone. It does this by touching one or two tentacles at a time, over time the number of tentacles touched are numerous and
eventually the fish creates mucus that protects it from the sting cells of that specific sea anemone. Once the clownfish does
create a relationship with an anemone, it must stay with that specific anemone, because the stinging cells of individual sea
anemones are different.