Worms. (Sec 1-4)
Goals:
1. Identify the three main phyla of worms.
2. Describe the characteristics of each
worm phyla.
Characteristics of Worms.
1. Flatworms (Platyhelminthes)
2. Roundworms (Nematoda)
3. Segmented worms.(Annelida)
Characteristics of Worms…
Body structure
-worms are invertebrates with long
narrow bodies without legs
-worms have bilateral symmetry
-worms have a head, tail, tissue,
organs and organ systems.
Characteristics of Worms…
Nervous system
-the simplest organisms with a brain.
-have sense organs that are sensitive
to light, touch, and vibrations.
Characteristics of Worms…
Reproduction
-Exhibit both sexual and asexual
reproduction.
-Many species have separate male and
female individuals.
--Other species have one individual with
both male & female organs.
-Some reproduce asexually by breaking
into pieces.
Flatworms
Flatworms
- (tapeworms, planarian and flukes)
- flat and soft like jelly
--Many are parasites; who takes food from its
host
--Some flat worms are free living organisms
that glide over rocks, or swim in ponds.
Flatworms
Planarians
Flatworms
-Planarians
-Free living flatworms that are
-scavengers: feed on dead or
decaying material.
--Also predators that will attack smaller
animals.
-Have Eyespots: two dots that detect
light. Also have cells that can pick
up odors.
Tapeworms
Flatworms
-Tapeworms
-Parasitic flatworm.
- body is adapted to absorbing food from
host’s digestive system.
-Many can live in human hosts.
--Can live in more than one host during
their lifetime. (Fig 22. page 29)
Roundworms
Roundworms
(e.g: Hook worms, C.Elegans)
--Can live in nearly any moist environment.
-Difficult to see, but abundant.
-Some are free-living, some are parasites.
--Unlike flat worms, cylindrical.
--have a very efficient tube-like digestive
system.
Segmented Worms
Segmented worms
-earthworms, leeches and some sea floor
worms
-Body Structure
--made up of many linked sections called
segments
-have a long string of nerve tissue called
a nerve cord.
-have a digestive tube, one way with
two openings
-Circulatory system
--Closed circulatory system:
blood vessels.
Earthworms
Earthworms in the environment
-earthworms tunnel for a living, they come
out on damp or raining days
-seek leaves and decaying matter to take
underground
-need to keep skin moist,
-obtains oxygen through
moisture on its skin.
-Earthworms help loosen the soil, and
provide fertilizer.
Names: _______________________
Worms flow chart
WORMS
Round
Worms
(Nematoda)
.
.
Tape
worms
.
C. Elegans
.
.
Earth
worms
Names: _______________________
Sponges, Cnidarians and Worm
Comparison Chart
1. Animals
2. Phylum
3. Structure
4. Symmetry
5. Obtain food
6. Movement
7. Reproduce
8. Examples
Name: _______________________
Comparing Worms, Cnidarians, and Sponges
Answer the following questions.
1. What is the difference between the three types of worms?
2. What characteristics are common to all worms?
3. Describe how the stinging cells of cnidarians are used.
4. Describe two forms of cnidarians.
5. Describe how the immature and adult forms of sponges look.
6. How does a sponge obtain food and water?
7. In what ways are cnidarians more complex than sponges?
8. In what ways are roundworms more complex than cnidarians?
Sponges, Cnidarians and Worm
Comparison Chart
1. Animals
Sponges
2. Phylum
Annelida
3. Structure
polyps,
medusa,
tentacles, and
mouth
4. Symmetry
Bilateral
Symmetry
5. Obtain food
6. Movement
Parasitic,
Scavenger, or
Predator.
No
movements
7. Reproduce
8. Examples
Sexually
and
Asexually
Planarian,
tapeworms,
and flukes.
Comparing Worms, Cnidarians, and Sponges
1.What is the difference between the three types of worms?
Flatworms are flat parasites that obtain food from a host and have a digestive system with only one opening. Roundworms are
cylindrical and have a one-way digestive system that is open at both ends, like a tube. Segmented worms have bodies made up
of linked segments, a one-way digestive system, and a closed circulation system with blood vessels and a heart.
2.What characteristics are common to all worms?
Flat, round, and segmented worms all have tissues, organs, and organ systems. They are the simplest organisms with brains.
They also have bilateral symmetry, giving them heads and tails.
3.Describe how the stinging cells of cnidarians are used.
Cnidarians are characterized by stinging cells that inject venom. Stinging cells are used by cnidarians to capture prey and to
defend themselves.
4.Describe two forms of cnidarians.
Cnidarians may be either polyps—attached to the bottom like sea anemones—or medusas, free-floating "jellyfish.“
5.Describe what the immature and adult forms of sponges look like.
An immature larva is a hollow ball of cells that swims through the water. Eventually the larva attaches to a surface and develops
into a nonmoving adult sponge. The body of an adult sponge has an irregular shape and no symmetry.
6.How does a sponge obtain food and water?
Water enters through pores and flows into a central cavity. Whip like collar cells bend back and forth to move water through the
sponge. Water finally exits through large openings called oscula. A sponge feeds by using collar cells to strain particles from the
ocean water. Jellylike cells digest and distribute food through the sponge.
7.In what ways are cnidarians more complex than sponges?
Cnidarians are more complex than sponges because cnidarians have specialized tissues, while sponges have only specialized
cells.
8.In what ways are roundworms more complex than cnidarians?
Roundworms are more complex than cnidarians because roundworms have organs and organ systems, while cnidarians have
only specialized tissues.