Transcript Sponges and Cnidarians

Sponges and Cnidarians
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I. Introduction to the Animal
Kindgom
A. What is an animal?
1. Animals are heterotrophic (feed on
organic compounds)
2. Multicellular
3. No cell wall
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4. The bodies of most animals contain tissues.
5. Animals have epithelial, muscular,
connective and nervous tissue.
6. Over 95% of all animal species are grouped
into a group called the invertebrates (animals
without a back bone)
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7. The other 5%
contains animals in
the vertebrate
groups (animals with
a back bone)
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B. What animals do to survive
1. Animals carry out the following
essential functions: feeding, respiration,
circulation, excretion, response,
movement and reproduction.
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C. Trends in Animal Evolution
1. The animal kingdom starts with simple
animals and goes to complex animals.
2. Animal cells have evolved to carry out
different functions, such as movement and
response.
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3. Animals that reproduce sexually begin life
as a zygote or a fertilized egg.
4. The zygote undergoes a series of divisions
to form a blastula-which is a hollow ball of
cells.
5. A protostome is an animal whose mouth is
formed from the blastopore.
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6. A deuterostome is an animal whose
anus is formed from the blastopore.
7. The anus is the opening through
which waste leaves.
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8. During early development, the cells
of most animal embryos differentiate into
three layers.
9. Endoderm (inner most), mesoderm
(middle) and ectoderm (outer)
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D. Body Symmetry
1. Body symmetry is the way a body
can be divided. See page 662.
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2. Radial symmetry
is a body part that
repeats around the
center of the body.
Example: sea
anemone
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3. Animals with
bilateral symmetry
can be divided into
right and left sides.
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Asymmetry
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E. Cephalization
1. Cephalization is the concentration of
sense organs and nerve cells at the front end
of the body.
2. Most animals have a body cavity, which is a
fluid filled space that lies between the
digestive tract and the body wall.
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II. Sponges
A. What is a sponge?
1. Sponges area classified, as animals
because they are multicellular, heterotrophic,
have no cell wall and contains a few
secularized cells.
2. Because sponges are so different than
other animals, scientists think they evolved
independently from all other animals.
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B. Form and function in sponges
1. Sponges have nothing resembling a mouth
or gut, and they have no tissue or organ
systems.
2. Sponges are asymmetrical; they have no
front or back ends, and no left or right sides.
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3. Chanocytes are
specialized cells that
use flagella to move
a steady current of
water through the
sponge.
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4. Water leaves
through the large
opening called the
osculum.
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5. The movement of water through the
sponge provides a simple mechanism for
feeding, respiration, circulation and excretion.
6. Sponges have a simple skeleton.
7. In harder sponges, the skeleton is made of
spiny spicules
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8. Spicules are made by archaeocytes, which
are specialized cells that move around within
the walls of the sponge.
9. Softer sponges have an internal skeleton
made of spongin.
10. Sponges are filter feeders.
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11. Digestion takes place inside of the cells.
12. Sponges rely on the movement of water
through their bodies to carry out body
functions.
13. Sponges do not have nervous systems
that would allow them to respond to changes
in their environment.
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14. Sponges can reproduce either sexually or
asexually.
15. In most sponges they contain BOTH egg
and sperm. It usually produces it at different
times.
16. In sponges the sponge will release its
sperm and then it will float to another sponge.
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17. In sponges fertilization occurs inside
the sponge, called internal fertilization.
18. After fertilization they zygote
develops into a larvae.
19. A larvae is an adult form.
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20 The larvae of sponges are motile and are
usually carried by currents before they settle
on the sea floor.
21. Sponges can reproduce asexually by
budding or by producing gemmules.
22. Gemmules are groups of achaeocytes
surrounded by a tough layer of spicules.
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C. Ecology of sponges
1. Sponges are important in aquatic ecology.
2. They provide habitats for other marine animals.
3. There are some that are photosynthetic
therefore they produce oxygen for other organisms.
4. Sponges are filter feeders so they clean up the
water.
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III. Cnidarians
A. What is a cnidarinan?
1. Cnidarians are soft bodied, carnivorous
animals that have stinging tentacles arranged
in circles around their mouth.
2. They are the simplest animals to have
body symmetry and specialized tissues.
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3. Cnidarians get
their name from their
cnidocytes (stinging
cells.) they are
located on their
tentacles.
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B. Form and Function in Cnidarians
1. Cnidarians are only a few cells thick and
have simple body systems.
2. Cnidarians typically have a life cycle that
includes two different looking stages.
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3. Polyp and a medusa see page 670.
4. A polyp is slim with arm like tentacles. The
mouth points upward. Polyps are usually
sessile.
5. A medusa has a motile, bell-shaped body
with the mouth on the bottom.
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Polyp
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Medusa
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C. Feeding
1. After paralyzing its prey, a cnidarians pulls
the prey through its mouth and into its
gastrovascular cavity- a digestive chamber with
one opening.
2. Food enters and a waste leaves the body
through that opening.
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D. Respiration, circulation and excretion
1. After digestion, the nutrients are usually
transported throughout the body by diffusion.
2. Cnidarians respire and eliminate wastes
through their body wall by diffusion.
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E. Response
1. Cnidarians gather information from their
environment using specialized sensory cells.
2. Both polyps and medusas have a nerve net.
A nerve net is a loosely organized network of
nerve cells that together allow cnidarians to
detect stimuli.
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F. Movement
1. Different cnidarians move in different
ways.
2. An anemone moves by hydrostatic
skeleton.
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G. Reproduction
1. Most cnidarians reproduce both sexually
and asexually.
2. Polyps can reproduce asexually by budding.
3. In most cnidarians, sexual reproduction
takes place with external fertilization in the
water.
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4. External fertilization takes place outside the
female’s body.
5. The sexes are often separate (either male
or female)
6. The female releases eggs and the male
releases sperm.
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7. They float until they are fertilized into
a zygote and then a swimming larva and
finally back to a polyp. See page 672.
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H. Groups of cnidarians
1. Cnidarians include jellyfishes,
hydras and their relatives and sea
anemones and corals.
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2. The class
Scyphozoa contains
the jellyfish.
3. They live their
lives primarily in the
medusa stage.
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4. The class
Hydrozoa is mainly
polyps.
5. They grow into a
branching colony.
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6. The class
Anthozoa contains
sea anemones and
corals
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7. Sea anemones
are solitary polyps
that live at all depths
of the ocean.
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8. Most corals live as a
colony.
9. Hard coral colonies
are usually founded
when a motile larva
settles onto a hard
surface and develops
into polyp
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I. Ecology of corals
1. The worldwide distribution of corals is
determined by a few variables: temperature, water
depth and light intensity.
2. Many coral reefs are suffering from human
activities.
3. Coral bleaching has become common.
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4. High
temperatures can kill
the algae that
usually live in the
tissues of corals,
leaving behind white
skeletons.
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THE END
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