The earthworm belongs to the phylum Annelida. It has many segments and searches for food at night in the soil. Earthworms are important for enriching soil by turning over tons of soil and bringing nutrients to the surface. The lab involved dissecting an earthworm to observe its external and internal anatomy, including organs like the brain, hearts, and digestive system. Key differences from humans are that earthworms have multiple hearts and need to keep their skin moist at all times.

1. Earthworm Dissection Lab
Background: (taken from Nascoʼs dissection guide for the earthworm)
The earthworm belongs to the kingdom Animalia. It is part of the phylum group Annelida (segmented
worms). The body of an annelid is usually divided internally and externally into well-defined segments
which may be separated from each other by membranous partitions. Except for the posterior and head
regions, all segments are essentially alike. Other members of this group include the clam
worms and tube worms, which live in the ocean, and the leeches.
The earthworm hunts food at night and thus has been called a “night crawler.” It usually extends its
body from the surface opening of a small tunnel which it makes by “eating” its way through the soil.
The posterior end of the wormʼs body remains near the opening while the head end forages for
decaying leaves and
animal debris.
It has been estimated that an acre of good soil contains over 50,000 earthworms. By their continuous
foraging and tunneling these worms turn over 18 to 20 tons of
soil per acre and bring over 3 centimeters of rich soil to the surface every four to five years. Thus,
indirectly, the earthworm enriches farmland and provides for
more food in a rapidly expanding population.
Objective:
To see if a earthworm can have some human organs like the worms.
To see what is inside it.
Study both the outside of the worm and the inside of the worm.
To see the organs inside the earthworm.
How the organs work in the earthworm.
Method:

2. Get a dissecting tray, after getting all your materials you get your worm and also get 10-20 pins. Then
you find the dorsal side which is the front. After finding the dorsal side you pin the worm down at his
anterior the head and the posterior his anus. Also be sure that you are wearing your goggles at all time
because the alcohol may squirt out. After pinning the earthworm at his head (mouth) and his tail you get
a scissor. Next you cut the worm skin, but you got to do carefully. To cut a worm skin you must use the
tip of your scissor jab it in a little not a lot. Like just a tiny stab. Then you snip it and repeat. While you
are sniping the worm put some pins at his skin. Stretch out the cut skin as far as it can go. Then you pin
the skin. After the snipping and pinning you must find where are the organ systems is. Identify the
organs like the brain its heart. Be sure to measure the worm as well (didn't told us to do it). After
identifying the organs you go to your teacher and talk about the organs place. Finally you are done with
dissecting a worm. Hope you had fun cutting the worm.
Data:
1. How many pairs of setae are there in each segment of the worm?
One for each segment
2. Does each segment have setae?
Yes, each segment does have setae
3. How many segments does your earthworm have?
37
4. How many centimeters is your earthworm?
I do not remember.
5. How thick is the worm?
I do not remember.
6. How many grams does it weigh?
We did not weight it.
7. What is the name of the major swelling on the earthworm?
Clitcillan
8. What side of the earthworm is the lighter colored flattened section?
The flattened section is the Vertral

3. 9. Where are the four pairs of hairlike bristles found (be specific, what segments)?
10. By what structure is each segment separated?
Internal:
1. How many aortic branches did you find? How many should an earthworm have?
There are five aortic branches. Earthworms should have five aortic branches.
2. Which organ is the most prominent (stands out the most) in the internal anatomy of an earthworm?
The Seminal Vesicles.
3. An earthworm absorbs oxygen through its moist skin. How is this a poor adaptation for life on land?
There are some place where it does not rain so it's really bad and the worm will die
4. What is the function of the crop?
To store the food and to give to gizzard
5. What is the function of the gizzard?
Grinds the food to piece
6. Which structure was the most difficult to identify? Why?
The brain because the Pharynx is blocking the brain and it looks like one too.
7. Next to what structure is the brain located? How is the brain connected to the rest of the body?
It is located near the Pharynx. The brain is connected to the rest of the body by Doran Blood Vessel
8. How is the earthwormʼs digestive system adapted for extracting relatively small amounts of food
from large amounts of ingested soil?
The body is long enough to take large amounts of food from the soil.
9. Your dissection of the earthworm did not go beyond segment 32. What will you observe if you dissect
the remainder of the worm to its posterior end?
You will observe lots of poop and the doran red blood vessel. As well as the whole body of the warm.
10. How is the digestive system of an earthworm different from yours?
It body is different and much smaller than than are system and we don't absorb moist through are skin.

4. Analysis
Why is it important for the skin of the earthworm to remain moist at all times?
so it can keep moving through the soil and so it can survive.
Why is an earthworm’s blood red like a human’s?
Cause it warm blooded like us.
What is the scientific classification of an earthworm?
Why is hermaphroditism an advantage for this species?
Why is the earthworm an important component of the ecosystem?
Without the worms birds will not be able to eat which will mean that the bird species will die.
Conclusion
Name at least three similarities and three differences found in the earthworm and humans.
We both have red blood, a digestive system and brain. The difference is that the worms has 6 hearts,
body is small and we don’t need to stay moist.
What are three interesting facts you learned about earthworms?
That is has 5 hearts and a really small brain and also that it needs to keep it skin moist.
What was the best part of the dissection?
Getting to open the worm up and see what was inside.
What would you change to improve the lab?
Get bigger worms so it would be much better to see the body.