Earthworm Dissect Rev2015 1 
Patrick Farese
LAB- Earthworm Adaptations
Follow the procedures in this lab and answer the questions as you go. Answer these on a separate sheet. You can use your textbook, classroom charts, the worm itself or the internet to find the answers to the questions.
EXTERNAL STRUCTURE
Place a live earthworm on a damp paper towel in a dissecting tray. Observe its movements for a few minutes.
1. How can you tell the anterior end from the posterior end?
The anterior end has a prostomium, an over hanging lip located above the mouth. The posterior end has the clitellum, a reproductive feature.
Locate the mouth. Above the mouth is an overhanging lip called the prostomium. See if you can observe the earthworm extending the lip.
2. What do you think the function of the prostomium might be?
The prostomium functions as a seal for the worm's mouth, as a sensory unit, and can be used for navigation.
Observe the dorsal blood vessel which is visible through the earthworm’s thin skin.
3. What is the direction of blood flow in this vessel?
The blood flows towards the anterior end of the worm.
Locate the external swelling around the worm’s anterior end. This is the clitellum.
4. What is the function of the clitellum?
It's a reproductive organ that secretes a coccon/sac around the eggs when the eggs are deposited. While you are observing the worm it is probably reacting to the bright light in the classroom. 5. What is its response to light and what is the survival value of this behavior?
The earthworm tried to move to the moistest and darkest place possible instinctively avoid dehydration, over heating and death in a natural setting.
6. How do the overall external features of an earthworm (or lack of features) relate to the lifestyle of the earthworm?
The earthworm has basic features that satisfy it's limited activity, which include borrowing, eating, and reproduction; therefore, their anatomy does not need to be so sophisticated. Return the live earthworm to the container.
INTERNAL
LAB- Earthworm Adaptations
Follow the procedures in this lab and answer the questions as you go. Answer these on a separate sheet. You can use your textbook, classroom charts, the worm itself or the internet to find the answers to the questions.
EXTERNAL STRUCTURE
Place a live earthworm on a damp paper towel in a dissecting tray. Observe its movements for a few minutes.
1. How can you tell the anterior end from the posterior end?
The anterior end has a prostomium, an over hanging lip located above the mouth. The posterior end has the clitellum, a reproductive feature.
Locate the mouth. Above the mouth is an overhanging lip called the prostomium. See if you can observe the earthworm extending the lip.
2. What do you think the function of the prostomium might be?
The prostomium functions as a seal for the worm's mouth, as a sensory unit, and can be used for navigation.
Observe the dorsal blood vessel which is visible through the earthworm’s thin skin.
3. What is the direction of blood flow in this vessel?
The blood flows towards the anterior end of the worm.
Locate the external swelling around the worm’s anterior end. This is the clitellum.
4. What is the function of the clitellum?
It's a reproductive organ that secretes a coccon/sac around the eggs when the eggs are deposited. While you are observing the worm it is probably reacting to the bright light in the classroom. 5. What is its response to light and what is the survival value of this behavior?
The earthworm tried to move to the moistest and darkest place possible instinctively avoid dehydration, over heating and death in a natural setting.
6. How do the overall external features of an earthworm (or lack of features) relate to the lifestyle of the earthworm?
The earthworm has basic features that satisfy it's limited activity, which include borrowing, eating, and reproduction; therefore, their anatomy does not need to be so sophisticated. Return the live earthworm to the container.
INTERNAL