Download Chapter 33

Chapter 33
-Sponges
-Cnidarians
-Ctenophores
Objectives
• Describe: the basic body plan of a
sponge
• Describe: the process of filter feeding
in sponges
• Contrast: the process of sexual and
asexual reproduction in sponges
Vocabulary
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Sponge
Sessile
Choanocyte
Ostium
Osculum
Spongin
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Spicule
Filter feeding
Amoebocyte
Gemmule
Regeneration
Hermaphrodite
Vocabulary
Porifera
• Comes from the Latin
word meaning “porebearer”
Sponge
• an aquatic
invertebrate of the
phylum Porifera that
attaches to stones or
plants and that has a
porous structure and
a tough, elastic
skeleton
Vocabulary
Sessile
• describes an
organism that
remains attached to a
surface for its entire
life and does not
move
Choanocyte
• any of the flagellate
cells that line the
cavities of a sponge
Vocabulary
Ostium
• one of the small
openings in a
sponge’s body
through which water
enters
Osculum
• an opening in a
sponge's body
through which water
exits
Vocabulary
Spongin
• a fibrous protein that
contains sulfur and
composes the fibers
of the skeleton of
some sponges
Spicule
• a needle of silica or
calcium carbonate in
the skeleton of some
sponges
Vocabulary
Filter Feeding
• in an aquatic animal,
a method of feeding
in which the animal
traps organic material
that is floating in the
surrounding water
Amoebocyte
• in sponges and other
invertebrates, an
amoeba-like cell that
moves through the
body fluids, removes
wastes, and
participates in other
processes
Amoebocyte
Gemmule
• an asexual
reproductive structure
produced by some
freshwater sponges
Regeneration
• The re-growth of
missing tissues or
organs
Vocabulary
Hermaphrodite
• an organism that has
both male and female
reproductive organs
Body Plan of Sponges
• The phylum Porifera is made up of
sponges.
• Sponges are sessile invertebrates that
have no true tissues or organs. The
simplest sponges are shaped like hollow
cylinders.
Body Plan of Sponges
• The body wall of a sponge is composed of
two layers of cells that are separated by a
jellylike substance called mesohyl.
• Choanocytes in the interior layer draw
water through the ostia that penetrate the
body wall. The water leaves through the
osculum.
• The body is supported by a skeleton made
of spongin, spicules, or both.
Sponge Structure
Feeding and Digestion in Sponges
• Sponges feed by filtering small organisms
and organic matter out of the water that
passes through their body. This is called
filter feeding.
• Nutrients are distributed through the body
by amoebocytes, cells which crawl about
within the body wall.
Sponge Reproduction
• Sponges can reproduce both
asexually and sexually.
• They reproduce asexually through:
–producing buds or gemmules
–regeneration of missing parts
Sponge Reproduction
• They reproduce sexually through the
joining of egg and sperm.
• Most sponges are hermaphrodites,
which can produce both eggs and
sperm.
Sponge Reproduction
Cnidaria and Ctenophora
• Cnidaria (nie-DER-ee-uh)
• Ctenophora (tee-NAHF-uhr-uh)
Examples of Cnidarians
• Freshwater Hydra
• Stinging Jellyfish
• Flowerlike Coral
Body Plan of Cnidarians
• Animals in the phylum Cnidaria are
radially symmetrical aquatic invertebrates
that are more complex than the sponges.
• They have tissues and a few simple
organs.
Body Plan of Cnidarians
• The cnidairan body is either a sessile
polyp or a swimming medusa.
• Some cnidarians alternate between both
types during their life cycles.
Body Plan of Cnidarians
• The body of a cnidarian consists of two
cell layers:
– an outer epidermis
– an inner gastrodermis
• The layers are separated by the
mesoglea.
Body Plan of Cnidarians
• The gastrovascular cavity has a single
opening (the mouth) surrounded by
tentacles.
Feeding and defense in Cnidarians
• Cnidarians have cells called cnidocytes.
• Each cnidocyte contains a nematocyst.
• When a cnidocyte is stimulated, its
nematocyst ejects a filament that can
paralyze or ensnare prey.
Nervous System in Cnidarians
• The cnidarian nervous system is a diffuse
web of interconnected nerve cells called a
nerve net.
Classes of Cnidaria
• Class Hydrozoa
– This class includes
Obelia, man-o-war, and
the hydra.
– Hydrozoans may live as
polyps, medusae, or
mixed colonies.
– Pic. Of Portugese Mano-war.
Reproduction of Obelia
Classes of Cnidaria
• Class Cubozoa
– This class
includes box
jellies.
– Cubozoans spend
most of their lives
as medusae.
– Pic. of Box
Jellyfish
Classes of Cnidaria
• Class Scyphozoa
– This class includes
jellyfish.
– Scyphozoans spend
most of their lives as
medusae.
Reproduction in Aurelia
Classes of Cnidaria
• Class Anthozoa
– This class includes sea anemones and corals.
– Anthozoans live only as polyps.
– Brain Coral