Earthworm Dissection

External Anatomy

research your earthworm and also determine thedorsal and ventral sides. Locate the clitellum which is ~ above the anterior finish of the worm. Locate the mouth the the worm on the far anterior finish of the worm The openings towards the anterior that theworm room the sperm ductsThe openings close to the clitellum are the genital setae.

Locate the dark line that runs down thedorsal next of the worm, this is the dorsal blood vessel. The ventral blood vessel can be seen on the underside that the worm,though it is generally not as dark.

Locate the worm"s anus top top the far posterior end of the worm

note the swelling of the earthworm near its anterior side, this is the clitellum.

brand the earthworm pictured:

A = _________________________________ B = _________________________________ C = _________________________________ D = _________________________________

Internal Anatomy

You are watching: Earthworm anatomy worksheet

1. Ar the specimen in the dissecting pan DORSAL side up. 2. Find the clitellum and also insert the reminder ofthe scissors around 3 centimeter posterior (behind the clitellum). 3. Cut carefully all the means up to the head.Try to store the scissors sharp up, and only cut through the skin. 4. Spread the skin of the worm out, usage a needle to tenderness tear the septa (little thread choose structures thathold the skin come organs below it) 5. Location pins in the skin to host it apart, edge the pins the end so that they are not in your way.

Reproductive System

The first structures you probably see room the seminal vesicles. They room cream colored and located towards the anteriorof the worm. These are provided for developing sperm. Usage tweezers come removethese white structures from over the optimal of the digestive system that liesunderneath it.

Circulatory mechanism

The dorsal blood vessel (X) shows up as a darkbrownish-red courage running follow me the intestine. The heart or aorticarches (Y) deserve to be discovered over the stomach (just posterior to the pharynx). Closely tease far the organization to disclose the arches of the heart, the runacross the worm.How countless aortic arches can girlfriend count? ______

The ventral blood ship (Z) is opposite thedorsal blood vessel, and cannot it is in seen right now because the digestivesystem covers it.

brand the diagram (use the letters alongside the bold words above)


Does the earthworm have a closed or open circulatorysystem? ________________

Digestive mechanism

The digestive device starts at the mouth. Youwill map the organs all the means to the anus and also identify every on the worm.

Find the mouth opening, the an initial part after ~ themouth is the pharynx, girlfriend will see stringy things attached to either sideof the pharynx (pharyngeal muscles) . The esophagus leads from the pharynxbut you most likely won’t be able to see it, since it lies under the heart .You will uncover a two structures close to the clitellum. Very first in the orderis the crop , complied with by the gizzard . The gizzard leader to the intestine which is as long as the worm and also ends in ~ the anus .

*Use your scissors to reduced open the crop and also thegizzard. I m sorry one has the more tough exterior? ___________

Place in the correct order (number)

____ Anus ____ crop ____ Mouth ____ Gizzard ____ stomach ____ Intestine ____ Pharynx

Nervous System

Locate the mind at the much anterior region of the worm. That is an extremely tiny and also whitish colored. If girlfriend can"t uncover it, that is probably because it was damaged when you cut the worm. You deserve to locate the ventral nerve cord by remove the intestines and searching for a white string-like structure that operation the length of the worm and also attaches come the brain. Remove the intestines and also locate the ventral nerve cord.

Lab Analysis (Answer True of False; most of the answers have the right to be uncovered in this worksheet)

1. ____ The mind attaches to the ventral nerve cord.2. ____ The dorsal next of the worm is lighter 보다 the ventral side..3. ____ The clitellum is located toward the anterior finish of the worm. 4. ____ The esophagus lies beneath the pharynx5. ____ Earthworms space hermaphrodites. 6. ____ The ventral nerve cord and also the ventral blood vessel room connected. 7. ____ The pale string-like framework 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 watched from the worm"s exterior.10. ____ Serminal vesicles are part of the worm"s digestive system.


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Brand these structures on the image: pharynx, esophagus, crop, gizzard, aortic arches, brain, dorsal blood vessel, seminal vesicles, clitellum



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