Transcript Simple Invertebrates

I. Simple
Invertebrates
A. Characteristics:
1. All animals without backbones.
 2. Have external skeletons
(exoskeletons).
 3. Includes 97% of all animals.
 4. Sexual & asexual reproduction.
 5. Some are hermaphrodites –
posses both male & female sex
organs.

II. Invertebrate
Phyla
A.
Phylum
Porifera
Ex. sponge
1. Characteristics
a. Sessile – Adults are
permanently attached to a
surface & do not move.
 b. Filter feeders of
plankton.
 c. Can regenerate missing
body parts.
 d. Live in fresh & salt H2O.

2. Body Parts: See Handout
1. Ostia – tiny openings to filter.
 2. Collar cells - flagellated cells
to trap food.
 3. Amoebocytes - carry food to
other cells; help in reproduction
 4. Spongin - flexible protein
skeleton.
 5. Spicules - tiny needles of
silica or calcium carbonate that
make up the skeleton.

3. Reproduction
 a.
Asexual
•Budding – growth of new
organism on body of parent;
breaks off to form new
sponge.
•Regeneration – regrow missing
body parts.
•Gemmules- encasing produced
when conditions are bad.
b. Sexual
 Sponges
are
hermaphrodites.
 They produce both egg &
sperm in the same body,
but at different times to
prevent self-fertilization.
B. Phylum Cnidaria
 Means
“stinging
animal.”
 Ex. - Jellyfish,
hydra, coral, &
sea anemone.
Coral Reef
1. Characteristics:
 a.
Have radial symmetry.
 b. Live as individuals or
in colonies.
 c. Have tentacles with
“stinging cells”.
d. Have 2 body forms:
 1)
polyps - vase-shaped
body. Ex. - hydra
 2) medusas - umbrellashaped body. Ex. –
jellyfish
e. Live in fresh & salt
H2O.
2. Body Parts: See Handout
3. Reproduction
a.
Sexual - Sperm
fertilizes egg, then
zygote develops into
a larva, then into a
polyp.
b.
Asexual - Polyp
(formed in sexual
reproduction), forms
buds that become
tiny medusa.
Sea anemone
II. Invertebrate
Phyla Continued:
C. Phylum
Platyhelminthes
Flatworms
•Ex. - planaria,
tapeworms, &
liver flukes.
Planarian
1. Characteristics:
a.
Have bilateral
symmetry.
b. Have a dorsal &
ventral surface.
c.
Live in fresh & salt
water.
d. Planarians are freeliving scavengers.
e. Tapeworms &
flukes are parasites
(require a host).
2. Body Parts: See
Handout
Planaria
Tapeworm
Deer Liver Fluke
3. Reproduction:
a.
Asexual - binary
fission
b. Sexual – by internal
fertilization (they are
hermaphrodites)
Tapeworm Infection
D. Phylum Nematoda
Roundworms
•Ex. – hookworms,
pinworms, Ascaris, &
Trichina
Ascaris
1. Characteristics:
 a.
Have anterior &
posterior ends.
 b. Found everywhere.
 c. Are dioecious - have
male & female gonads,
but not both.
2. Body Parts:
a.
Mouth at anterior
end, anus at posterior
end.
b. Muscles are used
for locomotion.
3. Reproduction:
a.
Sexual
4. Parasitic Diseases:
a.
Trichinosis caused by eating
raw pork containing
the Trichina worm.
b.
Hookworm enters feet through
the skin (common in
the U.S.).
Hookworm
 3.
Pinworm - infestation
is common in children in
daycare settings when
they eat something that
has come in contact with
contaminated soil.
Pinworm
E. Phylum Annelida
Annelida
means “little
rings.”
Segmented Worms
•Ex. – earthworm &
leech
1. Characteristics:
 a.
Have bilateral symmetry.
 b. Live in marine & freshwater
& in soil.
 c. Have well-developed organ
systems.
 d. Have a coelum – fluid-filled
body cavity.
2. Earthworm Body
Organs & Systems: See
Handout
a. Digestive System:
1.
mouth, pharynx,
esophagus, crop,
gizzard, intestine, &
anus
b. Closed Circulatory
System:
1.
5 aortic arches,
dorsal & ventral
blood vessels, &
blood (colorless)
c. Excretory
System:
1.
nephridia &
anus
d. Nervous System:
1.
brain, ventral
nerve cord, &
ganglia
e. Muscular System:
1.
lengthwise
(longitudinal) &
circular muscles.
f. Reproductive System:
1.
clitellum,
ovaries, seminal
vesicles, & seminal
receptacle
g. Respiratory System:
NO
ORGANS oxygen diffuses
through the skin to
the blood vessels.
2. Reproduction:
Sexual
–
hermaphrodites, but
they do not fertilize
their own eggs.