Earthworm Dissection

External Anatomy

research your earthworm and determine thedorsal and also ventral sides. Situate the clitellum i beg your pardon is on the anterior finish of the worm. Situate the mouth that the worm top top the far anterior finish of the worm The openings towards the anterior that theworm space the sperm ductsThe openings close to the clitellum are the genital setae.

Locate the dark line the runs under thedorsal side of the worm, this is the dorsal blood vessel. The ventral blood vessel can be viewed on the underside that the worm,though that is commonly not together dark.

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

keep in mind the ede of the earthworm near its anterior side, this is the clitellum.

brand the earthworm pictured:

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

Internal Anatomy

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1. Ar the specimen in the dissecting pan DORSAL next up. 2. Find the clitellum and insert the tip ofthe scissors about 3 centimeter posterior (behind the clitellum). 3. Cut very closely all the method up come the head.Try to store the scissors spicy up, and only cut through the skin. 4. Spread out the skin that the worm out, use a needle to gently tear the septa (little thread like structures thathold the skin come organs below it) 5. Ar pins in the skin to hold it apart, angle the pins out so that they space not in your way.

Reproductive System

The first structures you most likely see are the seminal vesicles. They space cream colored and located towards the anteriorof the worm. These are supplied for producing sperm. Usage tweezers come removethese white frameworks from end the top of the digestive mechanism that liesunderneath it.

Circulatory device

The dorsal blood vessel (X) appears as a darkbrownish-red courage running follow me the intestine. The heart or aorticarches (Y) can be discovered over the stomach (just posterior to the pharynx). Carefully tease far the tissues to expose the arches of the heart, the runacross the worm.How countless aortic arcs can friend count? ______

The ventral blood courage (Z) is the contrary thedorsal blood vessel, and cannot it is in seen currently because the digestivesystem covers it.

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


Does the earthworm have a closeup of the door or open circulatorysystem? ________________

Digestive system

The digestive system starts in ~ the mouth. Youwill trace the organs all the method to the anus and identify every on the worm.

Find the mouth opening, the very first part after themouth is the pharynx, friend will check out stringy things attached to either sideof the pharynx (pharyngeal muscles) . The esophagus leads from the pharynxbut you more than likely won’t have the ability to see it, because it lies under the heart .You will discover a two structures close to the clitellum. An initial in the orderis the crop , complied with by the gizzard . The gizzard leader to the intestine which is as lengthy as the worm and ends in ~ the anus .

*Use her scissors to cut open the crop and thegizzard. Which one has actually the more tough exterior? ___________

Place in the correct order (number)

____ Anus ____ chop ____ Mouth ____ Gizzard ____ esophagus ____ Intestine ____ Pharynx

Nervous System

Locate the mind at the much anterior region of the worm. It is an extremely tiny and whitish colored. If girlfriend can"t find it, that is probably since it was ruined when you cut the worm. You have the right to locate the ventral nerve cord by removed the intestines and also searching because that a white string-like framework that runs the size of the worm and also attaches come the brain. Eliminate the intestines and locate the ventral nerve cord.

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

1. ____ The brain attaches come the ventral nerve cord.2. ____ The dorsal side 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 space connected. 7. ____ The pale string-like structure running the size of the ventral next of the worm is the blood vessel.8. ____ an earthworm has actually fourteen aortic arches. 9. ____ The dorsal blood vessel can be seen from the worm"s exterior.10. ____ Serminal vesicles are component of the worm"s cradle system.


See more: Br A Cardiac Monitor Is Used To Measure The, A Cardiac Monitor Is Used To Measure The Heart

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



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