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Transcript
Phylum Porifera
Porifera =
pore
bearers;
they are
sponges
Sponges
•About
15,000
species of
sponges
•Most
marine;
Some 150
species live
in
freshwater
Characteristics
• They are the simplest of multicellular animals.
• Their bodies are an assemblage of cells embedded
in a gelatinous mass and supported by a skeleton
of minute needlelike spicules and proteins.
• They are filter feeders that are attached to the
bottom of a river or the sea.
• They depend on currents to eat, and they depend
on the currents to wash way their waste.
Characteristics continued…
• They have no organs or true tissues. They
have no nervous systems. They have no
sense organs. They can be 2 mm in size to
2 meters in size. They either have radial
symmetry or no symmetry at all.
Phylum Cnidarians
Box jellyfish
This phylum includes hydras, jellyfishes, sea
anemones, and corals.
They live alone or in colonies.
Body Structure
• They are soft-bodied, carnivorous animals, that
have stinging tentacles arrange in circles around
their mouths.
• They are the simplest animals to have body
symmetry and specialized tissues.
They are a few cells thick and have simple body
systems.
• They are radially symmetrical and have a central
mouth and tentacles.
Stinging tentacles
They use their stinging tentacles to capture
prey and for defense.
• They each have a nematocyst. This is a
poison-filled, stinging structure that
contains a tightly coiled dart.
Reproductive
• They have a two staged life cycle; they are
polyps and medusas.
• Polyps are the cylindrical body with
tentacles. They don’t move.
• The medusas are belled shaped body and
motile.
Reproduction
They produce both sexually and asexually.
Polyps can reproduce asexually by budding.
In the Medusa form there is external
fertilization.
The male release sperm into the water and
the female releases eggs into the water.
Internal body structure..
• They have three layers: gastroderm (inner
lining where digestion takes place),
epidermis is the outer layer of cells, and the
mesoglea that lies between the two.
Feeding
• Feeding – Stung by tentacles and pulled into
the mouth
Other systems
• Circulatory, respiratory and excretion – All
take place by diffusion.
Movement and response
• Response – Gather info by specialized
sensory cells. They respond to touch and
have primitive eyes, which see light.
• Movement – Depends on the species. They
most often move by jet propulsion.