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Earthworm Dissection Guide

1) The document provides a 7-step guide to dissecting an earthworm. It instructs how to euthanize the worm, lay it out on a tray, make a shallow cut behind the clitellum, continue cutting the skin towards the head using scissors, sever the septum walls, pin the skin flaps, and identify the internal organs. 2) Key steps include euthanizing the worm in alcohol, pinning it dorsal side up on a tray, making a shallow cut behind the clitellum to open the skin without puncturing intestines, cutting and pinning the skin flaps to expose the internal organs for identification and study.

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JJ Almagro
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540 views4 pages

Earthworm Dissection Guide

1) The document provides a 7-step guide to dissecting an earthworm. It instructs how to euthanize the worm, lay it out on a tray, make a shallow cut behind the clitellum, continue cutting the skin towards the head using scissors, sever the septum walls, pin the skin flaps, and identify the internal organs. 2) Key steps include euthanizing the worm in alcohol, pinning it dorsal side up on a tray, making a shallow cut behind the clitellum to open the skin without puncturing intestines, cutting and pinning the skin flaps to expose the internal organs for identification and study.

Uploaded by

JJ Almagro
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Guide to the Dissection of an Earthworm

1) To euthanize your earthworm, place it inside a small


glass jar with a cotton balls heavily soaked with 70%
alcohol. Cover the jar and wait for the worm to stop
moving.

2) Lay the worm on the dissecting tray with its dorsal


side facing up (dorsal side is darker in color). Stretch
the worm enough to steady the body across the tray
before securing the head end and posterior end with
pins.

3) Using your scalpel, start with a small (up to 1 cm)


dissection posterior/behind the clitellum, cutting
towards the tail (if your specimen does not have a
visible clitellum, start 1 inch below the head). Go
slowly and make it shallow enough to cut just the
skin (if you go too deep, you will puncture the
intestines, indicated by a blackish discharge).

4) Insert the tips of small dissecting scissors into the


opening and continue cutting the skin towards the
head end. Again, make sure to ONLY CUT THE SKIN.

5) Using your forceps, carefully pull apart one side of


the flap of skin. Carefully drag a pin along the inside
of the skin to sever the septum walls to make it
easier to spread the skin. Repeat the same on the
other flap of skin.

6) Once the septum walls are severed, pin the skin flaps
on the tray. Pin it diagonally.

7) Identify and study the internal organs


Skill-building Activities (with answer key)
• Read the instructions carefully and answer accordingly. Good Luck!

1) Identify and label the structures on the external anatomy of an earthworm.


2) Identify the structures on the internal anatomy of an earthworm and state their function.

Structure Function
1

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