Lesson Plan 1- Meeting an Earthworm
Students participating in the National
Worm Survey must use the Key
to Reproductively Mature Earthworms Found in Canada. Before
they can use this key, students must become familiar with the
anatomical features of an earthworm. This activity is designed
to introduce students to earthworms and their anatomy. It is
also intended to encourage students to practice their science
skills of observation and recording information.
Key Concepts and Skills
Students will develop an understanding
of the nature of science as well as the social and environmental
contexts of science and technology.
Students will develop the skills required for scientific inquiry,
problem solving, communicating scientific ideas and results,
working collaboratively, and making informed decisions.
Students will construct knowledge and understanding of concepts
in life science and apply these understandings to interpret,
integrate, and extend their knowledge.
Students will be encouraged to develop attitudes that support
the responsible acquisition and application of scientific knowledge
to the mutual benefit of self, society, and the environment.
Key Terms: prostomium,
tumescences (GT), clitellum,
pubertatis (TP), setae,
Figure 1. The anatomy of an earthworm
Additional Science Information
Earthworm Anatomy - External Features
Earthworms are invertebrates.
That is, they do not have a backbone. Insects, sea
stars, spiders, jellyfish, and millipedes are other
examples of invertebrate animals.
Study the illustration of an earthworm shown below.
You will notice that earthworms have long, cylindrical
body that is divided into similar segments.
The grooves that extend around the body of the worm
show the arrangement of the segments.
Some species of earthworms have a body composed
of over 100 segments. How many segments does your
Earthworms have bilateral
symmetry. This means that if you cut the
earthworm down the centerline, the left side of
the body would be identical to the right side.
One of the key features
of an earthworm is the colour of its body. Some
species of earthworms have a dark-red or
red-violet body while other species are muddy-green.
However, there are species that do not have these
colours. For the purposes of Worm Watch,
these animals are said to have "other body colours."
Some species of earthworms have a tongue-like
lobe above the mouth called prostomium. The
prostomium is actually a sensory device. Earthworms
do not have a nose, eyes, ears, or hands to gather
sensory information about their environment. Instead,
they depend on their prostomium and sensory receptors
in their skin to "feel" their way through the soil.
The first body segment
is called the peristomium. The peristomium
contains the mouth.
Adult (sexually mature) earthworms have a distinct
swelling called a clitellum. It is located
about one-third of the way down the earthworm. The
clitellum is often white or orange in colour. It
produces most of the material secreted to form earthworm
cocoons. The clitellum forms a band that can be
flared, non-flared, saddle-shaped, or annular. It
is generally found between segments 26 and 33.
The clitellum is only found on adult worms. Young
or juvenile worms do not have a clitellum. The clitellum
of each species of earthworm has a distinct colour,
size, and shape. Another key structure found on
the clitellum is the tubercula pubertatis.
The diagram shows the shape and structure of the
clitellum. They may have any combination of shapes.
|Tubercula Pubertatis (TP)
The tubercula pubertatis (TP) is another
structure used to identify earthworms. The TP are
glandular swellings located on both sides of the
clitellum. They can assume a variety of shapes such
as long and narrow, triangular, or sucker-like.
The shape and location of the tubercula pubertatis
(TP) on the clitellum are key features used to identify
|Genital Tumescences (GT)
The genital tumescences (GT) are areas
of modified epidermis (skin) that do not have distinct
boundaries. These are openings through which follicles
of genital setae open.
The pattern and location of the GT are important
clues to identifying different species of earthworms.]
Locate the clitellum of a mature earthworm. The
shorter region to one side of the clitellum is the
anterior or head-end of the animal. This
end of the worm is usually more pointed than the
posterior end of the animal.
The prostomium is the first segment at the anterior
end of the animal.
Locate the clitellum of
a mature earthworm. The longer region is the posterior
or tail end of the earthworm.
The top-side of an animal
is called the dorsal surface. For example,
the fin you see in all shark movies shows the dorsal
fin of a shark just before it attacks. The dorsal
surface of some species of earthworms is darker
than its ventral surface.
The bottom-side of an animal
is called the ventral surface. In many animals,
the ventral surface is a lighter colour or shade
than the dorsal surface.
The periproct is
the last segment of an earthworm.
Each segment, except the first and last, have
tiny bristle-like structures called setae.
These structures help the earthworm to move and
act to sense the environment.
The number and arrangement of setae are important
clues to the identification of earthworms.]
The epidermis is the name
for the skin of an earthworm. It is the outer layer
of worm and it secretes a mucous.
|Collect living, adult earthworms
Remember, adult earthworms have a visible clitellum
- by digging in a garden
- buying from shops that sell worms for fish bait
- buying from shops that sell worms for vermicomposting
You will need
- one earthworm for every two students
||Storing earthworms until they
- you need to keep the earthworms damp soil
- add leaves and other vegetable matter to the soil
- earthworms do not like the light - keep in dark location
or in covered container
- set up an earthworm terrarium in classroom (see Discover
Soil activity for instructions)
Suggestion: Ask the students to bring worms from their garden
or somewhere near their home where they have permission to sample.
Then the students can practice sorting the earthworms into adults
and juveniles. It is important to have adult earthworms for
this activity so the students should try and bring a good selection
of earthworms but at the same time try to minimise damage to
For the Investigation
Apparatus and Materials
- Earthworms do not like the light. Remind your students
to keep the earthworms covered with the moist paper
towels as much as possible.
- Teachers may want to spend more time on this activity.
See extension ideas, as well as the Information and
Communication Technology integration section.
- Students are not expected to memorize the names of
- If you do not want to keep the worms after this activity,
place them into a plastic bag. Place the bag in the
freezer over night. The worms can be used for compost
or fish food.
- Do not add store-bought worms to the soil in your
community. They may be an exotic species and may compete
with the indigenous worms in your area.
Go over the instructions with your students. You may have
to read the instructions to younger students. Make sure they
understand that earthworms should be handled carefully and treated
If you do not have access to a computer during this investigation,
you may want to download the Earthworm Anatomy notes found in
the Worm Watch Resource section of the web site. Photocopy and
distribute one set of notes for each team.
Ask your students to copy the data charts into their science
notebook before giving them the earthworms.
Students should collect all of the materials before they are
given the earthworm. Remind the students to keep their earthworms
covered with moist paper towels throughout this investigation.
In the first part of the investigation, students make observations
and record these in a data table. Encourage students to make
very detailed observations and to use their sense of touch as
well as sight.
In the second part of the activity, students look at the anatomical
features that they need to find in order to identify the earthworm.
Students do not need to memorize the names of these structures.
However, they do need to be able to find these structures and
recognize the patterns made by the GT and TP within the area
of the clitellum. The patterns of the GT and TP are unique to
each species of earthworm.
Hints and Suggestions
Make an overhead transparency or use an computer-projection
system to show the genital tumescence (GT) and the tubercula
pubertatis (TP). Students may be concerned with the long names
but these are very important features used to identify worms.
Once again, earthworms do not like the light. Students should
keep the worms covered with a moist paper towel as much as possible
throughout the activity.
Caution students about a hand lens and the damage it can cause
to their eyes as well as to the earthworm. Some students may
have started a fire with a hand lens - you MAY want to use this
as way to remind them about the dangers of looking at the Sun.
Caution students to wash their hands with soap and water when
they are finished this investigation.
Place unwanted worms into a bag and put them into the freezer
overnight. The worms can then be used for compost or fish food.
Have students return their earthworms to the container and
clean up the mess.
Use an over-head transparency or other means to review all
of the main features of the earthworm with your students. Or,
photocopy an illustration of an earthworm and have students
label all of the key structures.
- Earthworms belong to the Phylum Annelida. Use your library
and/or the Internet to locate information on other worms found
in this phylum.
- There are other activities relating to soil ecology in Discover
- Design and develop a multimedia presentation that describes
the external features of an earthworm.
- Design and develop a web page that describes the external
features of an earthworm.
- Design and develop a database that includes all of the external
features you have studied to this point.
- Use graphics software to create an earthworm poster.
- Make a model of an earthworm out of modeling clay or play-dough.
Encourage students to place all of the structures they observed
in the investigation on their model.
- Write a poem or story about the earthworm they have observed.
- Draw a poster that shows the anatomy of an earthworm.
Assessing Student Learning
Rubrics are rating scales commonly used to evaluate student
performance. These scoring guides can be used to evaluate a
wide variety of activities. They are quick and efficient methods
of subjectively evaluating progress. However, you can make this
form of evaluation more objective by making the criteria more
specific. The more specific the criteria, the more feedback
you will providing your students. The following is a sample
rubric that you can use to evaluate the students in this activity.
At Level 1, student is performing below expected standard.
At Level 2, student is performing in the lower range of the expected
At Level 3, student is performing in upper range of the expected
At Level 4, student is performing beyond the expected standard.
student can follow directions
with minimal direction
|Student needs constant help to complete the activity.
||Student needs some help to complete the activity.
||Student needs minimal amount of assistance.
||Student does not require any assistance to complete the
choose right tools and materials with
|Student needs constant direction.
||Student needs some guidance.
||Student needs little guidance.
||Student can help others in the class.
|Handling the earthworms.
student handles worms
carefully and with respect
|Has limited respect and needs continual supervision.
||Student has some respect, but does need some supervision.
||Student shows good sense of respect and is careful with
||Student shows a great deal of respect and can supervise
student follows all safety procedures
with little prompting
|Student needs constant reminders to follow rules.
||Student needs frequent reminders to follow rules.
||Student needs minimal reminders to follow rules.
||Student follows rules and leads other to do so.
student cleans up work space with little
|Student needs constant reminders to clean up work space.
||Student needs frequent reminders to clean up worm space.
||Student needs minimal reminders to clean up work space.
||Student does not need to be reminded and leads others
to do so.
Student can identify most of
the parts of an earthworm.
|Student can identify few parts of the earthworm.
||Student can identify some of the parts of an earthworm
||Student can identify most of the parts of an earthworm.
||Student can identify all of the main parts of the earthworm.
works will with other members of the
class or team
|Student needs continual reminders to work with others.
||Student needs frequent reminders to work with others.
||Student works well with others members of their group.
||Student works very well with others and shows leadership
(to be determined by the teacher)
(to be determined by the teacher)
Black Line Masters
- Blank Worm Diagram
[48k PDF] - Use the Key Terms in this lesson to label the
parts of the earthworm.