How do you dissect an earthworm step by step?

Place the earthworm on its ventral side. (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. Be careful not to cut too deep or you will slice into the digestive system.

How do you distinguish between the posterior end and the anterior end?

Anterior or ventral – front (example, the kneecap is located on the anterior side of the leg). Posterior or dorsal – back (example, the shoulder blades are located on the posterior side of the body). Medial – toward the midline of the body (example, the middle toe is located at the medial side of the foot).

What is the anatomy of an earthworm?

An earthworm consists of a digestive tube housed within a thick cylindrical muscular tube that forms the body. The body is divided into segments, and furrows on the surface of the body mark the division between each segment. The first segment encloses the mouth, and has a fleshy, muscular lobe on the top.

What can you learn from dissecting a worm?

Dissections allow us to examine the internal structures of organisms that we normally see only in textbook diagrams. Seeing the size, color, and shape of these structures up close adds so much to the understanding of how life works. Take some time to properly prepare to get the full benefits.

When dissecting an earthworm which surface is cut?

Go slowly and be sure to cut just the skin—if you go too deep you may damage the internal organs. 2. Using the forceps and dissection pins, carefully pull apart the two flaps of skin and pin them flat on the tray.

What happens when you cut worms in half?

One half — the one with the brain — will typically grow into a full worm. Scientists have now identified the master control gene responsible for that regrowth in one particularly hardy type of worm.

How can you tell the difference between the dorsal and ventral side of an earthworm?

The dorsal surface of some species of earthworms is darker than its ventral surface. The bottom-side of an animal is called the ventral surface. In many animals, the ventral surface is a lighter colour or shade than the dorsal surface. The periproct is the last segment of an earthworm.

How do you identify the dorsal and ventral side of an earthworm?

3. Notice that the earthworm has a rounded dorsal (back) surface and a flatter ventral (belly) surface. Usually, the dorsal surface is darker than the ventral surface (though sometimes this is obscured in the preservation process). Lightly rub your finger along the ventral side toward the posterior end of the worm.

What is an earthworm dissection?

Earthworms are important helpers in the garden or field! Their tunneling mixes up the soil and brings rich soil to the surface. You can observe the organs of these tiny creatures by dissecting a preserved earthworm. Our earthworm dissection guide will walk you through the entire process. 1.

What is the external anatomy of an earthworm?

External Anatomy. Examine your earthworm and determine the dorsal and ventral sides. Locate the clitellum which is on the anterior end of the worm. Locate the mouth of the worm on the far anterior end of the worm. The openings toward the anterior of the worm are the sperm ducts. The openings near the clitellum are the genital setae.

How can I observe the organs of an earthworm?

You can observe the organs of these tiny creatures by dissecting a preserved earthworm. Our earthworm dissection guide will walk you through the entire process. 1. Find the anterior (front) end of the earthworm by locating the fleshy bump over its mouth, called the prostomium.

What are the incisions for dissection of a worm?

Incisions for Dissection © 2016 Ward’s Science All Rights Reserved 2 Illustrated by Veronica Zoeckler Lay the worm dorsal side up. Pin the cranial and caudal ends. Incise beyond the clitellum, then extend the cut to both ends, from the middle out.