Transcript sponges - csmithbio

SPONGES
PORIFERA
I was part of
the
Cambrian
explosion!
Where do they live?
• In fresh and salt water
• Extremely porous; names means “porebearer”
• No gastrula stage; loose multicellular
organization; no true tissues
• Sessile as adults - attached
Body Plan
• Asymmetrical; hollow cylinders
with top opening “osculum”, lined
with collar cells with flagella
“choanocytes” to circulate water,
nutrients, wastes, and gases for
respiration.
• Water enters through the pores
and exits through the osculum.
OSCULUM
Chonaocytes could be derived
from the ancestors of the animal
kingdom, the chonanoflagellates.
• skeleton made of:
– (a) spongin – made of the protein collagen
– (b) spicules – made of calcium carbonate
or glasslike silica
spongin
spicules
How they feed
• Filter-feeders
• contain amoebocytes – specialized
cells that move nutrients, wastes, and
sperm and also make spicules
osculum
pore
spicule
pinacocyte
choanocyte
flagellum
spongocoel
amoebocyte
mesenchyme
(Jelly-like material)
• No nervous system but some secrete
toxins
Reproduction
• Asexual – form buds (gemmules) during
hard times; also regeneration (replacing
lost body parts)
• Sexual – flagellated sperm swim into
pores and fertilize the egg.
• The larva is flagellated and can
swim away.
• Sponges are hermaphroditic
• and can produce both eggs and
sperm.
• They do not self-fertilize.
• Eggs and sperm are produced at
different times.
Sponge Development
Importances of the Sponges
• Habitats for many aquatic organisms
• Symbiotic relationships with photosynthetic
organisms; sponge provides protection for
food from the partner; may help in
camouflage - ex. sponge crab
• Commercial use
Can you find the sponge crab?
Sponge video 14 min)
http://shapeoflife.org/video/sponges-origins
CNIDARIA
Jellyfish, corals, sea anemones
and other stingers...
Characteristics
• Soft-bodied, carnivorous animals with
stinging tentacles
• Name Cnidaria comes from their
cnidocytes, or stinging cells. The
cnidocytes contain nematocysts which
is the stinging structure.
Cnidarians are Protostomes
which means their mouths
develop first from the
blastopore opening.
Body Structure:
• Have true tissues and TWO cell layers:
- an epidermis derived from ectoderm
- a gastrodermis derived from
endoderm which lines the
gastrovascular cavity
• A jelly-like substance, mesoglea, is found
between these layers and may be very
prominent as in the jellyfish.
mesoglea
Cnidarians have two cell layers.
• have radial symmetry
• have two body shapes:
polyp - vase-shaped and
medusa – bell-shaped
• Some exist as colonies of both shapes
such as the Portuguese Man – of – War.
• Polyp forms are sessile or attached. Some
can move infrequently though.
Is this a polyp or medusa?
• Have only ONE opening, hence a “sac”
gut.
• Digestion takes place extracellulary in
the gastrovascular cavity and food
particles diffuse into the cells.
Flagellated cells move water through
the cavity.
• They depend on diffusion to move
nutrients, waste, and gases through
their bodies.
Mouth/anus
EPIDERMIS
Basal disk
new features…
• The first animals to have a diffuse
nervous system (nerve net)
• Also have specialized cells to
determine a sense of gravity
• Have eyespots to sense light
We can move…
• For movement, the first animals to have
muscles.
• Their skeleton is hydrostatic (water
supported with muscles)
• Some jellyfish use jet propulsion for
movement.
How do we reproduce?
• Reproduction can be asexual by
budding in warm weather or sexual,
involving EXTERNAL fertilization.
• Sexes are separate.
• The larva is free-swimming.
• Some members go through both body
types and sexual and asexual
reproduction in their life cycles, such
as the Aurelia jellyfish.
Asexual reproduction in the
hydra
Bud
Aurelia – showing both asexual
and sexual reproduction
Tutorial 32.1 Life Cycle
of a Cnidarian
Aurelia
jellyfish
Ciliated larvae
Importances of the Cnidarians
• Many depend on symbiotic
relationships with algae for food (also
give them color).
Zooxanthellae
Symbiotic relationships with
other animals
Corals are small polyps that live
in colonies and secrete an
underlying skeleton made of
calcium carbonate (limestone)
which form coral reefs.
The little coral animals
look like tiny sea
anemones poking out of
their limestone skeleton
The coral pieces you see on the
beach are skeletons that are left
over after the coral animals have
died.
How are coral communities
threatened?
Coral communities are threatened by
• Overfishing
• Sediments from logging clouding the water
preventing photosynthesis of the symbiotic
algae
• Human damage from walking on them or
dropping boat anchors on them
• High temperatures causing bleaching or
death of the coral animals and/or the algae.
Coral reef distribution
Variables that affect coral reef distribution:
temperature, water depth, light intensity.
Coral Bleaching
If the present rate of
destruction continues, 70% of the
world's coral reefs will be
destroyed by the year 2050.
Take care of our coral!
Sea Fans
• Sea fans are corals with an internal
limestone skeleton.
Classes of Cnidarians
• Scyphozoa – jellyfish; medusas only
The Box Jellyfish is said to be the most toxic of all jellyfish
and a sting from them can easily kill a human because their
venom leads to paralysis, which often leads to drowning.
The majority of jellyfish stings occur in the Atlantic Ocean
(near Florida) and along the eastern coast of Australia.
Death Toll: 100+ per year
• Hydrozoa – hydras, Portuguese-Man-of-War;
Hydras are polyps; P. Man of War is a colony
of polyps and medusas.
Hydras are good cnidarians to
look at in our class.
Mouth/anus
EPIDERMIS
Basal disk
• Anthozoa – sea anemones, corals, sea fans;
polyps only
Now, that is a jellyfish!
Cnidarian video (14.4 min)
http://shapeoflife.org/video/cnidarians-life-move