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Phylum Porifera
(pore bearers)
pages 664 to 667
Sponges
YouTube - The wonderful world of the
sea sponges- The Abyss- BBc Wildlife
Sponges
Scuba sponge
Glass sponge
Variety
Unidentified sponge
Phylum Porifera
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sponges
various shapes, colours, sizes
at least 10 000 species
may live alone or in colonies
Have no tissues therefore limited (no muscle,
no movement; no nerve tissue, no coordiation)
Characteristics of Phylum Porifera
1. Multicellular – Specialized cells in two main
layers
a. Outer layer: Epidermis (flattened cells)
: Protective Layer
b. Inner layer : Flagellated cells that set up water
currents, drawing H2O which carries its food into
the sponge
• Between these 2 layers is a jelly-like substance
containing:
a. spicules:
-provide support as they are made of silicon
(glass) or calcium carbonate (lime).
-provide protection from predators. (Sharp
needles in mouth!)
b. amoebocytes which:
- are not specialized but can carry food particles
(diatoms, algae) and water that were digested by
the collar cells.
- pick up waste and carbon to take back to the
collar cells for disposal
Sponge eating
• http://www.youtube.com/watch?v=RmPTM96
5-1c&feature=related
Choanocytes (Collar cells)
Characteristics continued
2. Motile when “young”; sessile as adults
3. Body cavity exists as a hollow sac with many
pores and one large opening called the
osculum (at top). Food is digested in the collar
cells.
4. Reproduce asexually and sexually.
Asexually by budding (small groups of cells
grow from the body wall of the adult and
break off to attach somewhere else) and by
fragmentation.
Budding
Sexually: Most are hermaphrodites (organisms
that produce both eggs and sperm but not at the
same time so they do not fertilize themselves).
They need another sponge of the same species.
EX. Sperm is released into the water and enters
a pore of another sponge. It enters a collar cell
where an amoebocyte takes it to an egg. A zygote
results. Mitosis (cell division) occurs to develop a
flagellated larva. It is motile but will settle on a
surface and grow into an adult.
• Spawning Sponges - YouTube
Questions
• Page 667 1, 2,
1. What features do sponges share with other
animals?
2. How do sponges use water to carry out
essential functions?
4. Why would sponges not be able to live on
land?
Phylum Cnidaria
(Cnidarians)
• Jellyfish, sea anemones, hydras, and corals
http://www.youtube.com/watch?v=AjMWOeM3uA
Phylum Cnidaria
• 90 000 species
• aquatic, mostly in salt H2O (all except hydra)
• very beautiful
Characteristics
1 Radially symmetrical (Tentacles arranged
around an opening like spokes on a wheel)
2 Have 2 embryonic germ layers: ectoderm
(outside) and endoderm (inside). Ectoderm
and Endoderm separated by jelly-like
material.
3. Exist in one of two basic shapes:
- when young: a tube-like, vase-shaped hollow
body called a polyp. The upward facing mouth
is surrounded by tentacles. Sessile.
- when mature: opened umbrella shape or
bell-shaped called a medusa. The downward
facing mouth is surrounded by tentacles.
Motile. (Ex. Jelly fish, Aurelia)
4. Possess nerve tissue but no brain. Respond
to stimuli when touched—flatten out and pull
in tentacles
6. Carnivorous
-Tentacles have specialized cells containing
nematocysts (coiled stinging hair-like
structures). Each is attached to a fine thread
that pulls food into the mouth. 1000s+ in one
tentacle. Nematocyts penetrate prey or
predator and paralyze them.
Nematocysts at work
Eating continued
- No digestive system. Food enters the mouth
with the help of the tentacles. Enzymes are
secreted by endoderm cells.
- Some endoderm cells use phagocytosis to
engulf large particles and digestion then
occurs in the endoderm cell itself.
Note: There is no need for an organ systems
because there are only 2 layers of cells. Water
can diffuse in and carbon can diffuse out.
7. Reproduction:
- Asexually by budding
- Sexually when conditions are harsh.
Many are hermaphroditic but some have
different sexes. The ectoderm develops the
gonads which are organs for sexual
production: male-testis
female-ovary
Sperm swims.