![]() Once you have observed the structures of the earthworm, dispose of the specimen in accordance with local guidelines and your teacher’s instructions.Also locate the seminal receptacles and seminal vesicles.Locate the excretory organs called nephridia in each segment.Identify the cerebral ganglia and the ventral nerve cord that extends from them, down the ventral body wall.Identify the 5 pairs of aortic arches, or hearts, which circle the esophagus. In this lab, you will dissect a frog in order to observe the external and internal structures of frog anatomy.Remove part of the intestine posterior to the gizzard and locate the ventral blood vessel.Using the diagram above, identify the organs of the digestive system:.Identify the thin walls between each segment.Using forceps, spread the incision open and pin the body wall to the dissecting pan as shown in the illustration.Be careful not to cut too deep or you will slice into the digestive system. (The ventral side is more flattened than the dorsal side.) Using dissecting scissors, cut through the dorsal body wall posterior to the clitellum and continue the incision toward the prostomium. Place the earthworm on its ventral side.It secretes mucus that holds 2 earthworms together during mating and produces a cocoon in which eggs and sperm are deposited for external fertilization. Get Free Worksheets In Your Inbox Print Animal Anatomy Worksheets Click the buttons to print each worksheet and associated answer key. It is important to determine which type of dissection is best for your student or child. The clitellum is the enlarged structure that begins at segment 31. This group of worksheets looks at the anatomy of frogs, earthworms, grasshoppers, starfish, crayfish, bony fish, and birds. Synthetic Frog Dissection Guide Project Frog dissections are a great way to learn about the human body, as frogs have many organs and tissues similar to those of humans.Also locate the openings to the sperm ducts on segment 15. Find the openings to the oviducts, which release eggs at segment 14, counting from the anterior end. 5 Before we proceed While dissecting, be respectful of your lab partners and of the specimen you are about to explore, observe and learn from. Earthworms are hermaphroditic so both sex organs are present.You may need to use a hand lens or stereomicroscope to see these openings. Each segment also contains a pair of small excretory pores called nephridiopores.Locate the tiny bristles on the ventral surface called setae.Earthworms are annelids, or segmented worms that have bodies made up of a series of ring-like segments.Locate the mouth opening and the prostomium at the anterior end. ![]() The earthworm has no head and no appendages, but it does possess external characteristics to study. The anterior end is somewhat larger than the posterior. First, identify the anterior and posterior ends.
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