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Worm RG/Lab
Flatworms (Ch.34): Phylum __Platyhelminthes___
Flatworms are the simplest creatures with __
They develop from __
bilateral__symmetry.
three__ germ layers (as opposed to Porifera, Cnidaria
Ctenophora that only had 2). They do not have a hollow __
body__
cavity___.
__
Because they are flat, they can exchange oxygen and CO2 with the environment
diffusion (their skin)__. They have no __circulatory__
through __
respiratory_ systems. They have an incomplete digestive system
or __
gut_ with a single _single opening__. Things go out the
consisting of a _
way they come in. Nerves and sensory organs are located at one end. This is known
as _
cephalization__.
parasites__, living on or in other creatures. Some
Many flatworms are _
are not and are found in freshwater, marine and terrestrial (land) environments.
Class Turbellaria:
Planarian__, such as Dugesia species

Includes the __

Feed by _

Food is ingested through a __
scavenging for__ bits of decaying plant and animal matter
pharynx__ which is extended out from the
body

How do they get rid of excess water?
Network of tubes w/flame cells (cilia)

What are the cerebral ganglia, and what do they do?
Clusters of nerve cells…simple brain

Describe the two ways Planarians reproduce:
Sexually…hermaphrodites, fertilize each
other
Asexually…fission, splits in the middle
Color/label the diagram below. Examine the slides of Planaria. Draw and label any
parts you can identify.
Cerebral Ganglia
Eyespot
Gastrovascular cavity
Nerves
Mouth (pharynx)
Class Trematoda and Monogenea:
flukes__

Consist of parasitic __

They can live in the _
blood_, __intestines__, _lungs_, __liver__
endoparasites_.
or other organs and are called _

Ones that live on the outsides of their host are called
ectoparasites__.
__

How does a fluke stick to its host and what else does this structure do?

Anterior, ventral suckers
Draws in body fluids
Most flukes are _hermaphroditic_. Fertilized eggs are stored until
release, where __

tens of thousands__ may be released at a time.
Most have a complex life cycle that involves _
more__ _than__ __one___
host
One disease caused by flukes includes _schistosomiasis_, which affects
more than 200 million people each year in Asia, Africa and South America.
Look at the slide of Clonorchis sinensis (Oriental liver fluke) under the microscope
and identify any structures you can see

Class Cestoda:

Also known as _
tapeworms__, which can live in the intestines of almost
all vertebrates

At the anterior end is a structure known as the scolex. What is its structure
and function?

Hooks & suckers attach to host
Behind the scolex are the body segments called __proglottids__.

What happens to these during reproduction?
Mature and produce eggs…up to 100,000

How can a human become infected with a tapeworm?
Proglottid breaks off…onto vegetation…
eaten by 1 host…in muscle…we eat that…
hatches and lives in us
Look at the slide of Taenia pisiformis (a tapeworm from beef) under the
microscope. There are four sections. The top section is the scolex. Draw and identify
the hooks and suckers. The other three sections are the proglottids, in various stages
of maturity. Draw the most mature ones (4th one) and identify the ovary, uterus and
testis.
Roundworms (Ch.34): Phylum __Nematoda__
Roundworms have _
bilaterally_ symmetrical bodies and a fluid filled
internal organs__ and _eggs/sperm_ and for
space to store _
support. They have a complete digestive system, that is, one with __
two__
openings, unlike cnidarians, ctenophores and flatworms. Why is this a significant
advancement?
Food goes in one end and out the
other…different parts specialized for different
functions
They have separate _sexes__. The vast majority are _free-living__ on
land and in the water, and are parasites of plants and animals.
Identify what the following creatures can do in humans:

Ascaris:

Hookworms:

Trichinella:

Pinworms:

Filarial worms:
live in intestines, feed on digested food,
block intestines
clamp on to intestinal wall, feed on
bloodanemia
In wall of intestinespain, muscle
stiffness, death
live in lower intestine…crawl out anus
at night to lay eggs
live in lymphatic system
elephantiasis
heartworms
Look at the slides of Trichinella in muscle and draw what you see.
Segmented worms (Ch. 35.2): Phylum __Annelida__
Feather-duster worms, common _
earthworms_ and __leeches__ are
all members of this phylum. The phylum name means __
little rings____. These
bilaterally_ symmetrical and, like mollusks, have a true
organisms are _
coelem__, a complete internal body tube. What does this structure allow to
__
happen when the organism moves?
Different parts expand and contract
independently
Most have external bristles called __setae__. All organ systems are
complete__.
_
Class Oligochaeta:
earthworm__.

The most familiar member of this class is the __

Describe how it moves (and the structures involved):
Anchors 1 segment (setae), contracts
circular muscle, sends anterior forward,
seta grab, longitudinal muscle contract
pulling posterior forward.

Complete or incomplete digestive tract? Explain.
Complete…two openings…pharynx, crop,
gizzard, intestine, anus

Open or closed circulatory system? Explain.
Closed…blood completely in vessels…5 aortic
arches (‘hearts”)
diffuse__ directly through the skin.

Oxygen and CO2 _

Earthworms get rid of wastes through tubes called _
are they found?
nephridia__. Where
On each segment

The nervous system consists of a chain of _
ganglia__ connected by a
nerve cords_. Segmented worms don’t really “think” like we
ventral _
do, but what can they respond to?
Light, touch, chemicals, moisture,
temperature, vibrations

How do earthworms reproduce? Be sure to mention any special structures and
their functions.
Hermaphrodite…can’t fertilize self…anchors at
clitellum
We’ll look at the structures of the earthworm when we do the dissection. Until
then, look at the earthworm c.s. (cross section) slides under the microscope and
identify any structures you can see.
Class Hirudinea:
leeches__.

Consists of about 500 species of __

They have no setae. At each end is a _
sucker__ that can attach to
surfaces.

What two things do they secrete when they suck blood?
Anesthetic…so don’t feel it
Anticoagulant…so don’t stop bleeding