This activity is appropriate for upper elementary through high school students and addresses the following National Science Education Standards:
- Grades 5–8, Science as Inquiry: Abilities Necessary to Do Scientific Inquiry; Life Science: Structure and Function in Living Systems
- Grades 9–12, Science as Inquiry: Abilities Necessary to Do Scientific Inquiry
Your students see them squirming in freshly turned garden soil, shriveling on hot pavement, or dangling from fishhooks. Maybe they even sing about them, as in
“Nobody likes me, everybody hates me, I think I'll go eat worms! Big fat juicy ones . . .” With this dissection you will give students the inside story on earthworms—and for good reason.
The earthworm is an ideal specimen for teaching both dissection and basic anatomy. It provides an economical and convenient opportunity for students to:
- Practice dissection techniques before progressing to more complex (and more expensive) specimens such as frogs or pigs. Earthworms are very simple to dissect. Students need only a pair of scissors to make the single cut down the ventral side of the specimen.
- Apply observational and analytical skills. Since the earthworm is small, students must be very attentive to details within the specimen’s body. Methodically opening and observing organs in each section of the earthworm are important skills to master.
- Learn basic anatomy based on the earthworm’s highly developed internal systems. Students can observe and make comparisons to vertebrate animals or other worm types. This can lead to discussions about structures present in all animals. You may want students to create Venn diagrams to show these observed similarities, as well as differences.
- Investigate simple digestive, nervous, reproductive, and circulatory systems. All of the earthworm’s systems are included in its simple linear body. Many internal structures of these systems are easier to find in earthworms than in mammals, which have structures layered and hidden under other organs. The linear simplicity also makes the structures easy to identify and understand.
The Young Scientist’s Animal Dissection Kit provides everything needed to dissect and study 4 specimens: frog, earthworm, crayfish, and grasshopper. Each specimen includes its own easy-to-follow color instruction manual with step-by-step instructions for observing structures, dissection procedures, and basic inquiry. Preserved in
Carolina’s Perfect Solution®, the specimens are ideal for use in your home, classroom, or lab. They are safe and nontoxic with no mandated disposal requirements, so they may be disposed of in the trash.
(Excerpt from the
Earthworm Dissection Student Instructions, “Observing Internal Anatomy” section)
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| Click on image to enlarge. |
- Place the earthworm in the dissecting tray dorsal surface up and fully extended. Use scissors to make a small cut through the body wall, about 10 segments posterior to the clitellum.
Insert the point of the scissors into the cut, and continue cutting the earthworm along the dorsal midline toward the
first segment. Be careful to cut only the body wall of the earthworm; avoid damaging the soft internal structures.
- Gently open the body wall. Notice the many cross-walls, or septa. Cut through the septa on each side with scissors, and then pin the body wall to the tray as shown in the photo. Insert the pins at an angle, so they will not be in the way of your observations.
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| Click on image to enlarge. |
- Using a hand lens, locate the earthworm’s digestive organs. Food enters the mouth and then the pharynx (4). From there, it moves through the esophagus (5) to the crop (6). The crop stores food until it enters the gizzard (7). The gizzard is a hard organ that grinds up food. The long intestine (8) absorbs nutrients from food before waste is excreted through the anus.
- Earthworms have 5 small hearts (9) located behind the esophagus at segments 7 through 11. Can you find any of the earthworm’s hearts? The thin, dark line running from the hearts down the length of the body is the dorsal blood vessel (10), an important part of the earthworm’s circulatory system.
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| Click on image to enlarge. |
- Locate the seminal vesicles (11) and the seminal receptacles (12). These are the reproductive organs of the earthworm. Earthworms are hermaphrodites. This means they have both male and female reproductive organs.
Now that you’ve seen a portion of the earthworm dissection, order the complete kit. Your young scientists can use their inquiry skills to learn about basic dissection techniques and the internal and external anatomy of 4 very different animals. The Young Scientist’s Animal Dissection Kit contains everything your students need to complete the mini-lab.
Are you ready to teach your students more detail about earthworm anatomy? Use
Carolina’s Earthworm Dissection BioKit® that includes 30
Carolina’s Perfect Solution® earthworms and a teacher’s manual with student guide. The detailed guide sheets allow students to identify many more internal and external organs.
Carolina carries an extensive selection of classroom dissection kits and
Carolina’s Perfect Solution® specimens to assist you in teaching anatomy. Learn more at
www.carolina.com/preserved, where you’ll find product information and secure ordering, plus classroom resources, activities, and additional teaching tips.
