Download Sponge and Cnidarians

Invertebrates:
Sponges and Cnidarians
Journal 2
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You are an expert taxonomist who has been
given an unknown specimen to identify.
You suspect that it is an animal. How could
you prove your hypothesis?
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Open your books to page 664
Sponges:
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Phylum Porifera means- pore
bearer
Simplest of all animals
Assymetrical animals that live in
shallow waters
Sessile filter-feeders whose bodies
have many pores
Acoelomates-no body cavity
Obtain oxygen by filtering water
Uses: cleaning, bathing, cosmetics
No nervous system or organ systems
Sponge Reproduction
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Reproduce Asexually by
budding:
Buds form from sides of
parent sponge, bud break off
and grow into new individual
can grow back missing parts
(regeneration)
Reproduce sexually:
Hermaphrodites: produce
both eggs and sperm
Gametes are released into
water
Sponge Body Structures:
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Osculum: large
opening at the top of
the sponge
Pore cells: openings to
bring in water
Collar cells
(choanocytes): line
interior, have flagella
to help filter water
Spicules: hard,
supportive structures
found in body of
sponge
LABEL THE SPONGE ON YOUR LEFT
PAGE!!!
The Anatomy of a Sponge
Section 26-2
Osculum
Central cavity
Pores
Water flow
Choanocyte
Spicule
Pore cell
Pore
Epidermal cell
Archaeocyte
Cnidarians:
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Phylum Cnidaria: means
“stinging cell”
Marine
Radial symmetry
Have tentacles
Predators: capture and poison
prey with stinging cells on
tentacles (NEMATOCYST)
Acoelomates
Oxygen diffuses into body from
water
Cnidarian Body Forms
Polyp: body with
tentacles hanging
upward
 Ex: hydra, sea
anemone
 Medusa: body with
tentacles hanging
downward
 Ex: jellyfish
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Cnidarian Reproduction:
Asexually reproduce by
budding
 Sexually reproduce in
medusa form only, sperm
and eggs are released into
water
 Thousands of gametes are
released at a time
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Time to Think!
Why do sponges and cnidarians release
so many gametes into the water?
The body plan of an animal relates to its
complexity. What does that tell you about
sponges and Cnidarians since they are
both acoelomates?
Cnidarian Structures:
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Label the hydra on
your left page
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Basal disc: sticky end of polyp
form which allows them to stay in
one spot
One body opening (mouth) for
food to enter and wastes to exit
Gastrovascular cavity: interior
cavity where food is digested &
nutrients are circulated around the
body
Nerve net: net of nerves that
allow impulses to travel around
the body, senses the environment
Muscles: some muscles are
present; allows for some
movement
Three groups of cnidarians
Hydrozoans: colonies which
appear to be one organism
 Ex: portugese-man-of-war
 Scyphorozoans: independent
medusas
 Ex: jellyfish, box jellies
 Anthozoans: colonies of polyps
 Ex: corals, sea anemones
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Quiz
1.
2.
3.
4.
5.
Sponges __ animals.
a. are
b. are not
Sponges can reproduce asexually by ___.
a. budding b. regeneration c. both
Hydras have their tentacles pointing upwards. They
are __.
a. medusas b. nematocysts c. polyps
All cnidarians have ___ symmetry.
a. bilateral b. radial c. no symmetry
Cnidarians poison their prey with stinging cells called
___.
a. choanocytes b.nematocysts c. osculum