Sponges and Cnidarians
Life Science
Review the Animal Kingdom
• 4 Major Characteristics?
• Multicellular
• Eukaryotic
• Heterotrophs
• Cells lack cell walls
7 Essential Functions?
• Feeding
• Response
• Respiration
• Movement
• Circulation
• Reproduction
• Excretion
Hard Shells
Phylum
Porifera
“Pore-Bearers”
Sponges are the
simplest of all animals.
They are multicellular,
heterotrophic, have no
cell walls, and have
specialized cells.
Sheet sponge
Carnivorous- eat small crustaceans
Adult sponges
are sessile.
CAN”T MOVE
They live attached to
a single spot.
Sponges are
asymmetrical filter
feeders
Feed on : bacteria,
unicellular algae, and
protists through filter
feeding.
IV. Phylum- Porifera (“pore bear”) –
sponges – simplest of all animals
A. Body Plan – asymmetrical,
pores all over body with large
hole on top called osculum
where water is pumped
through, Have no mouth or gut,
Have no tissues or organ
systems, Simple functions are
carried out by a few specialized
cells
B. Protection: skeleton of
spicules (glass-like material) or
spongin (soft)
Asymmetrical?
Have no front or back ends, no
left and right sides
– A large, cylindrical water
pump
– The body forms a wall
around a large central
cavity through which
water flows continually
Protection- Silica (cells
of glass offer protection
and support
C. Feeding – filter feeders, trap microorganisms
in water flow.
1. Collar cells - specialized
cells that use flagella to
move a steady current of
water thru the sponge.
Each collar cell digests
its own food.
2. Archaeocytes specialized cells that
make spicules
3. Pore cells – Cells thru
which water flows into
the body of a sponge
Major Body Functions
D. Respiration/ Circulation/
Excretion – water flow
carries out all body
functions (osmosis and
diffusion)
• As water moves through the
cavity:
1. Oxygen dissolved in the
water diffuses into the
surrounding cells
2. Carbon dioxide and other
wastes, diffuse into the
water and are carried
away
Major Body Functions
E. Response/Movement- no
nervous system, do
produce toxins, adults
don’t move (sessile),
larva swim
F. Reproduction- sexually
with internal fertilization
between two different
sponges or asexually by
budding or fragmentation
Osculum
A large hole at the top of
the sponge, through which
water exits
The movement of water
provides a simple
mechanism for feeding,
respiration, circulation and
excretion
The Anatomy of a Sponge
Water flow
Osculum
Central cavity
Pores
Collar Cell
Spicule
Pore cell
Pore
Epidermal cell
Archaeocyte
Ecology of Sponges
1. Ideal habitats for marine animals such as snails,
sea stars, sea cucumbers, and shrimp
2. Mutually beneficial relationships with bacteria,
algae and plant-like protists
Sponge Life Cycle (Sexual Reproduction)
Sponges are hermaphrodites.
MEIOSIS
Adult sponge
releases sperm into
the water
Haploid (N)
Diploid (2N)
New sponge
Sperm (N)
Mature
sponge (2N)
Egg (N)
Larva attaches
to a hard surface
The zygote
develops
into a free
swimming
larva
Larva
(2N)
FERTILIZATION
Sperm fertilize eggs
inside the body of
another sponge
Review Questions
Answer the 4 questions on your own.
Asexual Reproduction-Budding
A new polyp genetically identical to the parent is formed.
Jelly fish
Lion’s Mane Jelly
Some have eyes!
Box Jelly
Colony of polyps
Deadly within 3
minutes!
Over 100 deaths
in the last 25
years
Found off the
coast of
Australia
Chironex fleckeri
Anemones
Colonial
Anemone
Coral Reefs
Brain Coral
Orange Cup Coral
Red Sea Fan
Sea Pen
Feathery Hydroid
Fungiid Coral- this coral can move!
Carpet Anemone
Giant Sea Fan
Mushroom Coral
Solid Table Coral
Staghorn Coral
Phylum Cnidaria –more
complex than sponges
A. Carnivorous animals with stinging tentacles
around their mouths
B. Simplest animals to exhibit symmetry –
cnidarians have radial symmetry
C. Simplest animals to have true tissues including
nerves
Cnidarians have two body forms
Polyp - stationary,
vase-shaped
Medusa - swimming,
cup-shaped
Examples: hydra, coral,
sea anemone
Examples: jellyfish,
portuguese man of war
Examples: hydras, jellyfishes, sea
anemones, and corals
A. Hydrozoans: Most of life as polyp ex.
hydra
B. Scyphozoans: Most of life as medusa 
ex. jellyfish
C. Anthozoans: Only polyp stage in the life
cycle  ex. corals and sea anemones
Simplest animal with true tissues.
– soft bodied, have tentacles, radial symmetry,
1. Gut – gastrovascular cavity with one opening
2. Nerve net- detects stimuli
3. Hydrostatic Skeleton- movement and support
with the use of muscles
The Polyp and Medusa Stages
1. Polyp - Stationary, Examples:
Hydra, Coral, and Sea Anemone
2. Medusa- Swimming, Cup Shaped.
Examples: Jelly Fish and Man O
War
The Polyp and Medusa Stages
3 tissue layers
Epidermis
Mesoglea
Gastroderm
Tentacles
Bell
gut
Mouth/anus
Mouth/anus
Gut
Tentacles
Medusa
Polyp
1. Feeding- kill small prey with stinging cells
in tentacles, digest in gut, food in and
waste out of one opening.
2. Respiration/Circulation/Excretion- all by
diffusion (no true organs)
3. Response- have specialized sensory cells
and nerve net to gather info and react to
stimuli.
Response
a. Statocysts: groups
of sensory cells that
help determine the
direction of gravity
b. Ocelli: eyespots
made of cells that
detect light
(Stinging
Structure)
(Stinging Cell)
4. Movement- propel themselves with water
using hydrostatic skeleton
5. Reproduction- asexually by budding,
sexually by external fertilization, sperm
and egg are released and meet in water
IX. Ecology of Cnidarians
A. Source of new drugs/chemicals
sunscreen 855
B. Provide habitats for marine organisms
C. Source of food for other organisms (like
sea turtles)
D. Symbiotic relationships with other
organisms
Jellyfish Life Cycle (Sexual
Reproduction)
Female medusa
(2N)
MEIOSIS
Egg (N)
FERTILIZATION
Adult medusas
reproduce sexually
by releasing
gametes into
the water.
Sperm (N)
Zygote (2N)
Male medusa
(2N)
Young
medusa
Each zygote grows into a ciliated
larva. The larva eventually attaches to
a hard surface and develops into a
polyp.
Swimming larva
Polyp
The polyp
buds to release
young medusas.
Haploid
Diploid
Fertilization occurs in the open water,
producing many diploid zygotes.
Budding
polyp
Answer the 2 review questions