Name ____________________________________________
Date ___________________
Earthworm Observation
The earthworm, scientific name, Lumbricus terrestris, is a member of the animal phylum Annelida. An
earthworm is well adapted to a life of burrowing through the soil using its streamlined body. It also has a
mucus coating to lubricate the worm as it passes through the soil. The mucus coating also helps it to breathe by
allowing oxygen and carbon dioxide to pass through the skin. The earthworm moves through the soil by
sucking the soil in its path into its mouth with the help of a large muscular pharynx. Food will then pass through
the tube-like digestive system, being stores in the crop, ground up in the gizzard and then the nutrients will be
absorbed in the intestines, with the waste exiting out the anus.
In this investigation, you will examine the external and internal structures of the earthworm to see how the
earthworm is well adapted to its environment.
Procedure:
External Anatomy: Before beginning a dissection, one should always examine the specimen and then identify
all external parts.
1. Place all answers in the data table below.
a. Count the number of segments on your worm and record in table.
b. Measure the length of the earthworm in cm and record in table.
c. Count the number of segments between the mouth and clitellum and record in table.
Number of Segments
Length of Earthworm in cm
Segments between mouth
and clitellum
2. Rub your finger on the underside of the worm and feel the rough bristles. What do you think they are
there for?
3. Draw a picture of the worm and label the mouth, anus and clitellum (large ring with no segments on it)
on your diagram.
External drawing of the earthworm
Internal Anatomy:

Do not completely remove any body part unless instructed to do so. If a body part is to be
removed, leave it in the dissecting tray to be disposed of with the rest of the specimen.
1. Hold the earthworm in your hand with the darker colored dorsal side facing upward.
2. Using the scissors, insert the point of the scissors just behind the clitellum and under the skin. Cut with
the short, clipping motions with the point of the scissors pointing up to avoid cutting into the internal
structures.
3. Continue cutting all the way up to the very front of the worm, going through its lip.
4. Following the instructions for pinning the worm down onto the dissecting pan from your teacher.
5. Label the following parts of the earthworm on the diagram shown below.
a. Digestive system: Mouth, Crop, Gizzard, Intestines, and Anus
b. Circulatory system: Hearts and Blood Vessels
c. Reproductive system: Clitellum
G
A. _____________________
B. _____________________
C. _____________________
H
D. _____________________
F
E. _____________________
F. _____________________
G. _____________________
H. _____________________
Analysis: (Answer in full sentences please)
1. Discuss 3 ways how the earthworm is well adapted to its life in soil.