How to Dissect a Worm

Caveat: Earthworms have blood too. So be nice to them. If you are fortunate enough to go to a school where the pursuit of scientific knowledge is not being held hostage to PETA (or other ad hoc groups that consider anatomy and physiology politically incorrect, cruel and barbaric, etc...) the earthworm is your best bet for learning about life. Many a surgeon learned on something small and supposedly not cognizant - thus the earthworm. You will have to numb the brainstem of the earthworm as well. If the worm has circulation it can feel, so in the pursuit of knowledge, ethics must be present. Drop the earthwork in some alcohol is isopropyl- so that the poor thing can be studied painlessly.


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    Assemble your tools. You will need a Styrofoam tray, like the kind the butcher puts your steaks in, a selection of Exacto knives and blades, a shallow bowl filled with isopropyl alcohol and some pins with brightly colored balls on their tops as used in sewing.
    • Manicure scissors work well for those who cannot easily work with small things and fine detail. A magnifying glass with a light source is not a bad idea either. Unless you have especially gifted fine motor movement, use a toothpick to move things around, not your Exacto knife. Consider your toothpick like a surgical probe, and be gentle with it.
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    Find a big earthworm. If it is segmented and you see one or more bands, it is about to reproduce, so you may learn more. Worms can reproduce by themselves so do not feel guilty about dissecting a pregnant worm.
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    After you have observed the anesthetization of the earthworm, quickly remove it from the isopropyl alcohol and gently take the tip of your thinnest exacto knife blade and insert it into either end that shows an opening. If you have manicure scissors, you can cut instead, but in any case, do not go more than a quarter inch and keep the knife tip or scissors up, try not to go deep at all.
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    Quickly put a pin near your first incision so it is secure to the Styrofoam tray.
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    Continue gently cutting a line as straight as possible down the length of the worm.
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    Stop occasionally and gently pin the worm to the Styrofoam board by alternating your pins. If you find that you have rolling, gently take a toothpick and run it along your incision on one side only, because the tiny segments you see on the outside continue to the inside as ribs ( they are really muscles) so the worm tends to be ROUND . The toothpick breaks up the roundness so you can make it FLAT.
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    Pull up some images on the web so you can identify the brain, spinal cord, gut, intestines, anus.


  • Helpful Observation: If you hate using isopropyl alcohol to anesthetize the worms, wait till it has rained a lot, A drowned worm is easier to work on, but still use a little alcohol to make sure it does not undergo any pain. When you are done, put the earthworm into the earth and it will recycle itself organically.
  • The worm has mud in it, It is not pus. Be respectful of the fact that this small creature can literally move the earth, and does not need a hardhat and a big diesel shovel to do it. If it was not for earthworms, nothing would grow. There would be no such thing as dirt.

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Categories: Worms | Science for Kids