Name(s): ___________________________________________Date:________ Earthworm Dissection External Anatomy Examine your earthworm and determine the dorsal and ventral sides. Locate the two openings on the ventral surface of the earthworm. Locate the openings toward the anterior of the worm which are the s perm ducts. Locate the openings near the clitellum which are the g enital setae . Locate the dark line that runs down the dorsal side of the worm, this is the dorsal blood vessel. The ventral blood vessel can be seen on the underside of the worm, though it is usually not as dark . Locate the worm’s anus on the far posterior end of the worm. Note the swelling of the earthworm near its anterior side - this is the clitellum. Label the earthworm pictured. A_____________________________ B _____________________________ C _____________________________ D _____________________________ Internal Anatomy 1. Place the specimen in the dissecting pan D ORSAL side up. 2. Locate the clitellum and insert the tip of the scissors about 3 cm posterior. 3. Cut carefully all the way up to the head. Try to keep the scissors pointed up, and only cut through the skin. 4. Spread the skin of the worm out, use a teasing needle to gently tear the s epta (little thread like structures that hold the skin to organs below it) 5. Place pins in the skin to hold it apart – set them at an angle so they aren’t in the way of your view. Reproductive System The first structures you probably see are the s eminal vesicles. They are cream colored and located toward the anterior of the worm. These are used for producing sperm. Use tweezers to remove these white structures from over the top of the digestive system that lies underneath it. Circulatory system The dorsal blood vessel appears as a dark brownish-red vessel running along the intestine. The h eart (or aortic arches) can be found over the esophagus (just posterior to the pharynx). Carefully tease away the tissues to expose the arches of the heart. How many arches can you count? ______ The ventral blood vessel is opposite the dorsal blood vessel, and cannot be seen at this time because the digestive system covers it, find the ventral blood vessel on your worm. Label the diagram using the bold words in the section above. www.biologycorner.com Digestive System The digestive system starts at the mouth. You will trace the organs all the way to the anus and identify each on the worm. Find the mouth opening, the first part after the mouth is the pharynx, you will see stringy things attached to either side of the pharynx (pharyngeal muscles). The esophagus leads from the pharynx but you probably won’t be able to see it, since it lies underneath the heart. You will find two structures close to the clitellum. First in the order is the crop, followed by the gizzard. The gizzard leads to the intestine, which is as long as the worm and ends at the anus. Use your scissors to cut open the crop and gizzard. Which one has the harder exterior ______________________ Nervous System Locate the brain in the far anterior region of the worm. It is very tiny and whitish colored. If you can’t find it, it is probably because it was destroyed when you cut the worm. You CAN locate the ventral nerve cord by removing the intestines and searching for the white string-like structure that runs the length of the worm. Remove the intestine and locate the ventral nerve cord. Lab Analysis ( answer True or False) 1. ____ The brain attaches to the ventral nerve cord. 2. ____ The dorsal side of the worm is lighter than the ventral side.. 3. ____ The clitellum is located toward the anterior end of the worm. 4. ____ The esophagus lies beneath the pharynx 5. ____ Earthworms are hermaphrodites. 6. ____ The ventral nerve cord and the ventral blood vessel are connected. 7. ____ The pale string-like structure running the length of the ventral side of the worm is the blood vessel. 8. ____ An earthworm has fourteen aortic arches. 9. ____ The dorsal blood vessel can be seen from the worm’s exterior. 10. ____ Seminal vesicles are part of the worm’s digestive system. Label the image. www.biologycorner.com 4/22/2020 Frog Dissection Coloring Name: ______________________________________Date:________ Frog Dissection Coloring When the abdominal cavity of the frog is opened, many organs of the digestive and urogenital systems can be observed. As you read the descriptions of the organs below, color them on the diagram. 1. Leading from the mouth is a tube that connects to the stomach. Color the esophagus pink. 2. The largest organ is the liver, and it consists of multiple lobes. Color the right lobe (a) light brown. Color the left anterior lobe (b) medium brown, and the left posterior (c) lobe dark brown. The liver has several jobs related to digestion and detoxification. 3. Tucked under the liver is the gall bladder, which stores bile that is produced by the liver. color the gall bladder green and the bile duct (3b) a darker green. 4. The gall bladder connects to the duodenum of the small intestine. Color the duodenum light blue. 5. The duodenum connects to the curly part of the small intestine known as the ileum. The ileum is where nutrients are absorbed into the blood. Color the ileum dark blue. 6. The spleen is an organ that has an immune function and is found within the coils of the intestine. Color it red. 7. The ileum connects to the large intestine and the cloaca. Water is reabsorbed in the large intestine and wastes are stored at the cloaca before exiting the anus. Color this area orange. 8. At the lowest part of the abdominal cavity is a thin pouch for storing urine. Color the bladder yellow. 9. The stomach can be viewed if you lift the liver and is often curved, this is the first site of chemical digestion in the frog. Color the stomach orange. 10. Within the curve of the stomach is a gland called the pancreas. The pancreas is involved in the digestion and the uptake of sugars. Color the pancreas yellow. 11. The coils of the small intestine are held together by a thin membrane called the mesentery. Color it pink. 12. A female frog will have tiny curling tubes deep in the abdominal cavity that carry eggs. Color the oviducts red. 13. Also deep within the cavity are bean shaped organs, the kidneys which filter wastes from the blood, creating urine which is then stored in the bladder. Color the kidney gray. 14. Task – after reading the descriptions, write down the structure based on the description. Use the bold words above. _________________________ Carries eggs in female frogs _________________________ First site of chemical digestion _________________________ Stores solid waste, eggs, sperm _________________________ Filters blood, makes urine _________________________ Digestion, uptake of sugar _________________________ Holds the coils of small intestine _________________________ Stores urine _________________________ First part of the small intestine _________________________Stores Bile 15. Task - COLOR the frog according to the directions and LABEL each structure next to the number. https://www.biologycorner.com/worksheets/frog-dissection-coloring.html 1/2 4/22/2020 Frog Dissection Coloring https://www.biologycorner.com/worksheets/frog-dissection-coloring.html 2/2 4/22/2020 Frog Dissection Crossword Name:___________________________________________ Frog Dissection Crossword ACROSS DOWN 1. Membrane that covers the eye 4. Opening in the mouth, airway 2. Can be large or small, helps digest food 7. Tubes that equalize pressure to the eardrum 3. The largest organ in the frog's body cavity, having 3 8. Regulates food exiting the stomach, pyloric ______ lobes valve 4. The opening where waste, eggs, and sperm exit 10. System that includes the stomach and intestines 6. Located underneath the liver; _____ bladder 14. The very first stretch of the small intestine 9. Long tube that runs around the kidneys, carries eggs in 16. The esophagus leads to this structure females 17. Membrane that functions as an eardrum 11. The lower (single) chamber of the frog's heart 19. Located above the kidneys, but only in male frogs 12. Used to capture food, attaches to the front of the 20. Teeth at the roof of the mouth mouth 21. Spiderweb-like membrane that covers the heart and 13. Stores urine; urinary _______ other organs 15. Opening in the mouth where food enters 18. Famous from from the Muppets https://www.biologycorner.com/worksheets/frog_dissection_crossword.html 1/1 4/22/2020 Student Guide to the Frog Dissection Name: _______________________________________ Student Guide to the Frog Dissection Dissection Instructions 1. Place the frog in the dissecting pan ventral side up. 2. Use scissors to lift the abdominal muscles away from the body cavity. Cut along the midline of the body to the forelimbs. 3. Make transverse (horizontal) cuts near the arms and legs. 4. Life the flaps of the body wall and pin back. *If your specimen is a female, the body may be filled with eggs. You may need to remove these eggs to view the organs. Locate each of the organs below. Check the box to indicate that you found the organs. 1. Fat Bodies --Spaghetti shaped structures that have a bright orange or yellow color, if you have a particularly fat frog, these fat bodies may need to be removed to see the other structures. Usually they are located just on the inside of the abdominal wall. 2. Peritoneum A spider-web like membrane that covers many of the organs, most easily seen covering the heart.