Transcript cnidarians ppnt 2011

Journal #1: KWL on Cnidarians
K- What do you
know?
W- What do you
want to know?
L- What have you
learned?
PHYLUM CNIDARIA
HYDRAS, JELLYFISH,
SEA ANEMONES,
CORAL, BOX JELLYFISH
I.
General Information
1.
“Cnido” means nettle
(stinging cell)
2.
EX: hydras, jellyfish,
sea anemones, coral
3.
Symmetry: Radial
4.
Found in marine &
freshwater
5.
Diploblastic: two
tissue layers
a. Ectodermdevelops into
epidermis
(skin)
b. Endodermdevelops into
gastrodermis which
lines the “stomach”
(gut cavity)
General
Body
Plans:
Basal disk
Polyp &
Medusa
II. Body Forms
1. Polyp
a. Cylindrical, column-like body
b. Mouth points up, surrounded by
tentacles
c. Sessile,
attached to
surface by
basal disc
2.Medusa
a. Bell or cup shaped body
b. Mouth points downward surrounded by
tentacles.
c. Free swimmingmoves by gently
pulsating body
III. Digestion/Feeding
1.
Use cnidocyte
containing
nematocyst on
tentacles to
sting/stun prey
2.
Eat daphnia,
protists, larva, etc
3.
Stuff food into
mouth using
tentacles at oral
end.
4.
Food is digested
by special cells in
the gastrodermis
that line the
gastrovascular
cavity.
5.
Wastes leave thru
mouth.
1. The cnidocyte contains the nematocyst- fluid filled
capsule with coiled thread.
2. Prey trigger the cnidocil (trigger hair), operculum
(lid) opens & thread containing barbs stabs/entangles
prey.
3. Cnidocyte degenerates & a new one takes its place
IV. Respiration
1. DIFFUSION through cell membranes
directly exposed to water.
V. Skeleton/support
1. Hydra & sea
anemones have a
hydrostatic
skeleton- fill
gastrovascular
cavity w/water.
Gives support
2. Aids in movementsomersaults,
inchworm
3. Jellyfish mostly
float w/currents
4.
Coral are sessile
VI.Nervous System
1. Nerve net- layer
of nerve cells in
mesogleagelatinous middle
layer- that react
to stimuli.
2.
Most primitive
form of nervous
system in animal
kingdom.
3.
Jellyfish consist
of cells called
statocystssenses gravity,
coordinates
movement
VII. Excretion
1. Through mouth or directly into water from
cells.
VIII. Reproduction
1. Asexual
a. Budding- hydras, coral,
sea anemones
2. Sexual
a. Monoecioushermaphrodite, “one
house”
EX: hydra
b. Dioecious- sperm & egg
are produced in separate
sexes.
EX: jellyfish
IX. Jellyfish Life Cycle
1. Sperm released by
male medusa. Egg
released by female.
2.
Sperm & egg join to
form zygote.
3.
Zygote goes through
several cell divisions &
forms a hollow ball of
cells called a blastula.
4.
Blastula eventually
forms into a free
swimming larva called
a planula.
5.
Planula lands on a
structure & begins to
grow into a polyp.
6.
Polyp buds break off
& grow into free
swimming medusa.
X. Classification
Craspedacusta sowerbyi
(Cobb, Bartow, etc.)
Class Hydrozoa
* marine & fresh water
* can live as single animal or colony
* may be polyp or medusa
* gametes made on outside of body
* EX: hydra, Portuguese man-o-war
Class Scyphozoa
* all marine
* predominant medusa stage
* gametes made internally & released
thru mouth
* called “true jellyfish”
* EX: Aurelia
Lions Mane Jelly
Class Anthozoa
* all marine
* solitary or colonial polyps
* budding or can be monoecious or
dioecious
* anthozoa means “flower animal”
* EX: sea anemones, coral
Class Cubozoa
* all marine; found in warm tropical
water
* medusae are cube shaped; tentacles
hang down from each corner
* have deadly poison
(each tentacle with 500,000 cnidocytes; deaths in
Japan, Australia, Malaysia, Gulf of Mexico; suffer severe
physical and psychological symptoms )
* EX: sea wasp (box jelly)
XI. Economic/Environmental
Significance
1.
Part of food chain
2. Control animal
populations
3. Coral provide habitat
for other animals in
coral reefs
4. Some corals provide
medicines & jewelry
EX: Cancer, arthritis,
histamines, antibiotics
1. The stinging cell of the cnidarian is called
a. Cnidocyte
b. Ameobocyte
c. Gland cell
2. Jellyfish have both a sexual & asexual stage to
their life cycle.
a. True
b. false
3. Jellyfish are an example of which body form?
a. Polyp
b. medusa
4. The place where food is digested & gases are
exchanged is called the
a. Spongocoel b. Gastrovascular cavity c. Gland cell
5. The sticky adhesive base of a sea anemone is
a. Spongocoel b. Gastrodermis
c. Basal disc
DAILY QUIZ