Darwin Charles, considered to be the father of evolutionary thought, was able to determine how earthworms behave and the type of food they prefer through his dedicated studies of their anatomy and characteristics. He was particularly fascinated by their behavior and life.
By meandering in the earth (in soil) and through their feeding habits, Darwin was also able to explain their benefits in agriculture.
In the early years of microscopy, there was an intriguing belief among certain scientists and philosophers that sperm cells, also known as spermatic worms, were akin to parasitic worms.
Earthworm dissection
Examining the earthworm will facilitate the exploration of its inner structure.
Observation
The insect can also be observed beneath the microscope, dividing the minuscule body sections of a partition. The back end is situated at the rectum. The insect is situated near the oral region and is referred to as the prostomium, a fleshly protrusion that can be observed at the front part under increased magnification capability.
The anterior region of the worm, located close to the larger genital pores, should be easily visible in the clear image. Additionally, the setae (small hair-like bristles) and pores on each body segment of the worm will also be readily apparent. It is worth noting that the ventral surface of the worm, which is both darker and flatter, differs from the dorsal part.
Requirements/Material
Roundworms (round worms) under the microscope
When examined under a microscope, eelworms can be cultivated using culture media prior to the aforementioned worms. In contrast to the aforementioned worms, eelworms are considerably tinier.
Procedure
· Put the earthworm in a Petri dish.
· Rotate the spinning turret to position the objective with the lowest magnification in place.
· Gently position the Petri dish on the platform.
· When observing through the eyepiece, softly rotate the focal knob to bring the picture into focus.
· The condenser can be adjusted to control the intensity of light.
Once the image is properly focused, attempt to locate the front part of the worm and proceed with examining the remaining body structure.
· Adapt to high magnification and repeat the procedure to obtain a more detailed examination of the worm and document your findings.
The above steps can be repeated to observe the movement of a live earthworm, how the worm moves its mouthparts and body.
Observation
When examining under the microscope, it will be feasible to recognize various aspects of the internal structure.
These include:.
· Aortic arches (Heart) – Five shadowy coils encircling the esophagus function as the core of the worm’s cardiovascular system.
The pharynx is located at the anterior part inside the mouth of the worm and consists of several lightly colored organs and muscles that will appear.
The genitalia, located in proximity to the heart, will be noticeable as pale tissue or petite white organs.
· Gizzard – is situated behind the crop (functions to store nourishment).
· Intestine – a lengthy tube extending from the gizzard towards the rear portion of the body.
The neural cord will appear as a lengthy pale cord, and its visibility can be enhanced by displacing the intestine to one side. It is situated on the dorsal region of the organism’s body. This is the central nervous cord.
Observation
These pigmented cuts are sensitive to sunlight, functioning like eyes. The anterior part of the worm, specifically the spots on its head, can also be observed. If you use a microscope, you will notice that the body of this worm appears flattened and elongated, resembling a flat leaf.
It might also be possible that feeding is involved in the pharynx spot. These points are known as auricles and serve as sensory structures involved in touch and smell. The shape of the head may be pointed on the sides depending on the species.
Conclusion
You are encouraged to gather various varieties of worms in your vicinity (or even purchase them online) and analyze their anatomical features to investigate their adaptations for survival in different environments. There is a wide array of worm species present in our surroundings. While some are parasitic, many others live freely.
Also explore additional concepts: What appears fascinating under a microscope?, More enjoyable microscope experiments.
Go back to the Annelida phylum.
Resume studying about Flatworms.
Explore further about Roundworms, alternatively referred to as Nematodes.
And comprehend the study of nematology.
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Eelworms
Eelworms are significantly smaller in size. It would be difficult to differentiate their different body parts under the magnifying glass. However, they can be seen moving around in a group. Eelworms are worms that can be compared to earthworms and Planarians.
By utilizing a microscope, you will have the opportunity to examine the outer and inner (via dissection) structure of the earthworm.
Microscopy
After the slide has been prepared, the subsequent step is to observe the specimen under the microscope.
This will include the subsequent stages:.
· Prior to placing the slide, rotate the turret to position the lowest power objective in place.
· Gently position the slide onto the stage and secure it in place with the clips.
· Peer into the eyepiece and rotate the focus knob to align the image in focus.
· By utilizing the stage adjustment knob, carefully shift the stage to observe various sections of the specimen.
· Change to a higher level of magnification and examine the specimen.
· Bring down the stage before taking out the slide.
General Introduction to Worms
The body that is soft and elongated/slender is characterized by bilateral symmetry, worms exhibit variation in size and shape, and are divided into three primary categories: flatworms, roundworms, and segmented worms. These invertebrate animals are essentially characterized by these traits.
Engaged in locomotion, certain organisms possess filamentous appendages. Utilizing a group of muscles, they navigate by crawling on surfaces and lack limbs.
Worms can be found in a variety of habitats across the world. Polychaetes are abundant in marine habitats, while earthworms can be found in many moist terrestrial environments. Earthworms., like such worms, can be found in many moist terrestrial environments, specifically in decomposing organic material or soil.
Other organisms that can be found living as parasites are worms. These worms can form a symbiotic relationship with sulfur bacteria, and they are found on the sea floor, specifically the Tube worms (Riftia pachyptila).
Some of the additional traits linked with worms comprise:
Some instances of worms comprise:
Preparation Procedure
· Place a mixture of ethanol (1 part ethanol and 9 parts water) in a Petri dish.
One step in preparing an earthworm for microscopy involves picking it up with a pair of tweezers and placing it in an alcohol solution for killing.
Pick up the earthworm and place it in a Petri dish with water – this step aims to wash off any mucus or dirt on the epidermis.
Preparing Temporary Slides
Planarian Flatworms
In comparison to the middle (central portion of the body), the pharynx is situated in close proximity to the head region and eyespots. The tail, found at the posterior end, is sharper than the broader anterior section. Despite their elongated bodies, these flatworms are considerably smaller (ranging from 3 to 15mm) than earthworms, boasting a flattened, leaf-like shape.
Requirements/Materials
Planarian Flatworm under a Microscope..
Requirements/Material
Observation
If you observe a worm, you will notice that it has a transparent outer layer called the epidermis. The eelworm’s body is cylindrical and tube-like, with a pointed part at the posterior end and a mouth at the anterior end. When magnified, you may see that the intestine runs from the esophageal bulb towards the posterior part of the body, similar to the flatworm.
Requirements/Materials:
· Magnifying lens – A standard magnifying lens typically has a magnification strength ranging from 1× to 2×.
· Culture plate.
· Set of tweezers.
· Examples: Earthworm (segmented worm), a Planarian flatworm, and Nematodes (roundworms).
· Set of gloves (Nitrile rubber).
· Container.
· Sieve.
· Small Garden Spade.
* The three types of worms have been selected because they can be easily found (Earthworms.; found in gardens and loose soil, Planarian flatworms can be found in shallow water, ponds, and rivers while Eelworms can be found infecting various crops e.g. tomatoes) and are safe to handle. Moreover, they represent each group and will make the comparison process easy.
Procedure
* This method is employed to observe live worms.
· Add a drop of hot agar (4 to 5 percent agar) on a clean glass slide – Agar. used for this technique consists of Oxoid Agar. Technical and cupric sulphate
· Utilizing a different pristine slide, smooth out the agar.
· After the agar has solidified, carefully take out the slide (which is used to flatten the agar).
· Utilizing a dropper, include a single drop of water onto the agar.
· Gently introduce the flatworm onto the drop of water and cover it with a coverslip.
To prevent the flatworm from being crushed, a small amount of vaseline may be added gently to the edge of the coverslip before pressing it down on the specimen.
Observation
Culture
Microscopy
Stereo Microscopy
To examine the outer structure of the worm, a stereomicroscope can be utilized.
Requirements/Materials
Objectives
This will enable students to determine some of the differences and similarities between these worms. The main objective of observing a worm under a microscope is to compare each member of the segmented worms, roundworms, and flatworms groups.
At the conclusion of these activities, students should have the ability to:
It is always recommended to use a magnifying glass or a microscope to get a general idea of what the worm looks like before viewing it.
The magnification power of a microscope allows you to magnify the image several times in order to get a general idea of its morphology, compared to lower magnification power.
Procedure: collecting specimen
For the most part, these worms are harmless, however, you may use a pair of gloves in order to collect the specimen.
· Employing a small garden spade, delicately excavate around your garden or loose damp soils to locate one or multiple earthworms.
(You might need to partially cover the Petri dish to prevent the earthworms from getting away) Utilizing a set of tweezers, cautiously grasp the earthworms and transfer them into a Petri dish.
Depending on the species, they can be black, gray, or brown in color. They are small in size, ranging from 15 to 3 mm in length. If you were able to get the worm, you will have to take a closer look at the water in the container to see whether it can be seen (you can use the magnifying glass).
The earthworms can be conserved by incorporating a small amount of water in the Petri dish. Ensure that each variety of worm is stored in a separate Petri dish and strain the water to effortlessly gather the worm and retain them in a Petri dish once you are certain you have gathered the planarians in your container.
Identifying a contaminated crop (such as tomatoes or rhubarb, potatoes, etc) enables the collection of the eelworms. The task of collecting eelworms might pose difficulties due to their minuscule size (0.4-1.2 mm), making them significantly less visible to the unaided eye in comparison to the other two.
To gather eelworms, the subsequent procedures can be utilized:.
· Carefully separate the affected portion of the harvest (e.G. Foliage) into small fragments.
· Put the foliage in a glass receptacle filled with water for approximately half an hour.
· After half an hour, you will witness eelworms (in a group) crawling at the bottom of the container.
· Carefully pour out the water, being cautious not to lose the weight of the eelworms.
By incorporating a small amount of water or delicately pouring it into a Petri dish, one can retain the eelworms within the container.
The earthworms are present in the Petri dish. This task can be accomplished by closely observing them with a magnifying glass after collecting the complete specimen in each Petri dish.
Requirements/Materials
Earthworm
It may be challenging to perceive anything, which can result in a darker complexion for certain species. Additionally, if you are observing the internal organs of a worm, you may also have difficulty identifying some vessels. These segments enable the organism to move and twist. When observed under a magnifying glass, the segments along the entire length of the worm’s body will be clearly visible.
At the anterior part of the body, you will notice a narrow and pointed section. This segment is smaller compared to the other body segments. Additionally, if you observe the middle part of the body, you will notice a distinct segment that appears lighter in color and swollen. In comparison to the other body segments, this segment stands out.
Some of the additional sections that can be identified using the magnifying glass include:
Procedure
* Examine the sample under the microscope by following the aforementioned procedures.
Procedure
· Using a dropper, add approximately 200ml of the vinegar into a pristine glass culture dish.
· Slice a few pieces of apples and place them into the glass container.
· Introduce the nematodes into the container and loosely cover it (covering the container loosely to decrease evaporation).
· Oxygenate the culture utilizing a sterile pipette (to inject air into the culture medium).
The worms can be observed by looking at the Petri dish (with a dark paper beneath it) through a stereoscope.