2.To study the movement of the earthworm.

3.To examine the internal body parts and organ systems of the earthworm.

paper towellingrazor bladescissors6 live earthworms

dissecting trayprobespinspreserved earthworm

forcepshand lensscalpeldissecting microscope

PROCEDURE:

1.Place a preserved or live earthworm on moist paper towelling in your dissecting tray.

2.Examine the body of the earthworm. When necessary use a hand lens or the dissecting microscope to locate the following body parts:

anterior endventral surfaceanusprostium

posterior endsegmentssetae

dorsal surfacemouthclitellum

Place a live worm on a piece of damp paper towel in your dissecting tray. Observe the worm to try to determine how it moves. Let a worm move along your hand in order to feel how it moves. If necessary use a hand lens or the dissecting microscope.

4.Moisten your finger and run it gently along the ventral surface of the worm in each direction to feel the setae or bristles. Alternatively feel the setae on a preserved worm. Attempt to determine in which direction the setae point.

5.Draw a LARGE properly formatted diagram of the external features of the earthworm. Label all of the features indicated in Procedure 2 above.

6.Answer the questions in the Observations section for external features.

1.Place a preserved earthworm specimen on a piece of paper towelling in the dissecting tray. The worm should be lying on its VENTRAL side. Carefully pin the worm at each end through the prostium and anal segment.

2.On the DORSAL side carefully take a pair of tweezers and lift the skin about 3 centimetres behind the clitellum.

3.Using the razor blade make a small cut.

4.Insert the tip of a pair of scissors into the cut. Using only the tip of the scissors CAREFULLY cut the skin slightly off center through to the anus.

5.Beginning at the anal end hold the body wall with the forceps and with a razor blade or scalpel cut through the septa on both sides of the intestine. Cut to within 2 centimetres of the clitellum. Be extremely careful not to damage the internal organs.

6.As you cut, pull the skin gently back and away from the organs. Use pins to hold the skin away from the organs as illustrated.

7.Cut through the clitellum starting from the posterior end and pin the remainder of the body wall to the tray as illustrated. Examine the inside surface of the clitellum and note its appearance.

8.Examine the internal structure of the earthworm. When necessary use a hand lens or the dissecting microscope to locate the following internal body parts:

hearts (which segments?)mouthcropprostiumsperm sac

dorsal blood vesselpharynxgizzardintestineseptum

esophagusstomachanus

9.Draw a LARGE properly formatted diagram of the dorsal view of the internal features of the earthworm. Label all of the features indicated in Procedure 8 above.

10.Carefully clean your dissecting equipment and store as instructed.

11.Answer the questions in the Observations section for internal features.

OBSERVATIONS AND DATA:Answer the following questions in complete sentences.

2.Copy the following paragraph filling in the blanks to describe how the worm moves:

"When the worm moves forward the end that moves first is the (front, back) end. The shape of this end when the worm begins to move is (stretched, fat) while the shape of the back end that is not moving is (stretched, fat). While the front end is moving the back end is (anchored, also moving). When the back end moves the front end is (anchored, still moving) and has a (stretched, fat) shape. Finally when the back part has been pulled up the shape of the worm is (stretched, fat, round)."

3.The clitellum is closer to which end of the worm's body ? Does the clitellum go completely around the worm's body ?

4.Describe the location of the setae and state in which direction they point, forward or backward.

2.In which segments were the five hearts located ?

3.Describe the inside surface of the clitellum.

4.Is the worm segmented internally as well as externally ? If so, what divides the segments ?

1.What is the function of the clitellum ?

2.What is the function of the setae or bristles ?

1.By what structure are the segments separated from each other on the inside of the worm ?

2.Does the earthworm have a skeleton ?

3.How many pairs of hearts does the earthworm have ? Where are they located ?

4.Name the parts of the circulatory system that were visible and state the function of each part.

5.Name the parts of the digestive system that were visible and state the function of each part.

6.Name the parts of the reproductive system that were visible and state the function of each part.

1.Very briefly describe the external appearance of an earthworm.

2.Briefly explain how an earthworm moves.

3.List the parts of the digestive system of the earthworm in the order that it processes food.