Worms: Under The Microscope

Curious to know more about the inner workings of these weird and wonderful creatures? Looking at worms with our microscope can be a fun and exciting project for beginners.

It’s a great way to expose yourself to what’s beyond our field of vision, and it’s a great way to practice a fun experiment. 

Worms have been around for literal millennia! Evolving throughout hundreds of millions of years, the worm has undergone many, many changes of course- but the general structure remains the same!

According to an article published by the wonderful folks over at National Geographic, there was a recent discovery of a fossilized bristle worm that was over five hundred and eight million years old!

It even showed clear bristly hairs over its body and sensory tubular palps on it as well!

Though the bristle worms of today are slightly different, many of the same features and visual characteristics are pretty much identical to the bristle worm of today’s knowledge. 

This find was specifically well renowned as over this huge amount of time, this sort of tissue and body structure would have easily been destroyed, or decomposed.

To have a fossil that so clearly shows the segments and bristly body is pretty awesome, and it leads the way to hopefully discovering more well-preserved fossils!

This is another reason why looking at worms under a microscope is such a cool thing to do.

It shows us a small window into the past, looking at animals that were around long before mammals were a thing, and having more in common with leeches and earthworms that eventually evolved from these millions of year old bristle worm specimens. 

Earthworms were a particular fascination of the great Charles Darwin, who is largely considered the father of modern evolutionary biology.

His leading and groundbreaking work into these animals led to a dedicated study of their behavior, their preferred eating habits, and the earthworms’ various anatomy along with lots of other fascinating information that no one previously had bothered to study in-depth, or with as much vivacity. 

With Darwin’s long search into the life of the earthworm, he was also able to tell why they were so beneficial to agricultural practice and the health and wellbeing of our soil. 

FACT TIME: 

Here’s a weird one for you! Did you know that in the very early days of microscope use, sperm were thought to be parasitic worms by both scientists and philosophers of the age? 

What Are Worms?

There are three different types of worms. They are all invertebrate animals and are divided into these subsections- segmented worms, flatworms, and roundworms. 

Though the main principles of the animals remain the same, worms can vary in their shape, size, and where they can live. 

The main characteristics that they share are that they have a long body that is soft and malleable and that their body is bilaterally symmetrical.

That means that they are identical on both sides of their body, so they don’t technically have an ‘underside’ or ‘topside’ that looks different from one another. 

Worms’ most noticeable feature is of course that they are legless, and they, therefore, move by contacting their muscling body to edge forward across surfaces. 

Segmented Worms: There are over 22 000 subspecies of segmented worms. They are known as segmented worms because the sections of their long bodies are segmented, or separated into many repeated sections.

Most segmented worms feed on decaying matter, including species such as the earthworm, and leech, and also include some water-dwelling marine worm varieties.

Because they eat dead matter, the earthworm is amazing for regenerating soil and creating compost that can revive unusable organic debris into rich fertile soil that we can use to fertilize our crops and feed back into the land. 

Flatworms: The variety of worms known as flatworms is a group that has three defining characteristics.

They have bodies that can flatten (as the name suggests) and have only three layers of tissue comprising their bilaterally symmetrical bodies.

They have no respiratory system in the same way as we would usually think, and they have no body cavity. Types of flatworms include tapeworms, flukes, and planarians.

Platyhelminthes, or Land Flatworms, are often covered in slimy and sticky mucus that helps them to navigate the terrain and they are usually spotted by their slimy trail that follows in their wake.

Because they are so flat, they don’t even need blood in their bodies to survive! Instead, they absorb oxygen through pores in their skin which spreads directly to their nervous system and brain. 

Roundworms: Roundworms are worms that have a long, round body. They are also called Nematodes and come in an insanely varied range of lengths, from 2 millimeters to almost two meters!

These are common parasites and can live inside animals’ intestines, especially in dogs and cats, though they have been found in many others, including humans.

They live inside the intestine, feeding off partially digested food, and can be a serious cause of illness and infection if left untreated.

Varieties of roundworm include Hookworm, Threadworm, and Whipworm, amongst many others (over 15 000 different species!) Some species can even lay up to 200 000 eggs in a single day! 

Worm Characteristics

Here are some of the shared characteristics that are associated with most species of worm:

• Coelom- most worms have a body cavity (apart from flatworms who have nobody cavity at all).
• Digestive system- many species of the worm have a digestive system
• Nervous system- worms have a nervous system that is connected throughout their bodies. 
• Germ Layers- these layers are built up to build the body of the worm. 

Examples Of Worms

As we mentioned before, there are a huge amount of different types of worms, it would be impossible to list out every single one for you! Below is a short list of different examples of worms:

• Earthworm
• Leech
• Hookworm
• Tapeworm
• Yellow Papillae Flatworm

Observing A Worm Under A Microscope

What is the aim of observing a worm under a microscope? Well, there are a few reasons why this would be a fun and educational activity to do with students, kids, or even if you are just a budding microscope enthusiast! 

The main aim is for you or your students to compare an example of the three different types of worms and to discuss or elaborate on the differences that you can see between the three.

What makes them different or unique? Do they have any similarities in features or structure on a microscopic level? 

It is also a great way to introduce the use of a microscope. This activity will help to show how you can observe specimens and slices with the use of a microscope. 

It’s also a great activity to do if you want to compare and contrast different types of specimens to come to educated and reasoned conclusions. 

Part 1: Magnifying Glass

Before we get started with the microscope, it’s always a great idea to use a magnifying glass to get an idea of what your specific sample looks like in closer proximity. 

Whilst a magnifying glass is a lot less magnifying than a microscope, it can give you a better idea of the relative shape and size of various parts of your specimen. 

You Will Need:

• One magnifying glass that has a power of times one or times two
• A petri dish for your specimen
• A clean pair of tweezers
• One of each of the three types of worms- Segmented worm, Planarian Worm, Roundworm
• A pair of gloves
• A container
• A sieve
• A small shovel

There are three types of worms that we have selected because they can be easily found in your garden or amongst shallow ponds. 

We recommend trying to find an earthworm as your segmented worm, a planetarium worm that can be used as your flatworm example, and an eelworm that can be used as your roundworm example.

Earthworms can be found in your garden and loose soil, especially in an area that has decaying plant matter.  You can find planarian flatworms easily enough in rivers or shallow water. 

As for eelworms, you can find them infecting many different varieties of crops including tomatoes and we’ve chosen mealworms as their around worms that are safe to handle, unlike many other varieties. 

They are also really easy examples of the three types of worms which will make cross-examination and comparison a lot easier between the three. 

 How To Collect Your Samples

The first thing to do is put on a pair of gloves. These worm specimens are harmless. It’s important to keep yourself clean to prevent cross-contamination plus it’s a great habit to instill in general when doing scientific research or experimentation.

Using your small garden shovel you should dig around in your garden or loose soil to find some earthworms. We recommend finding more than one. 

Use your pair of tweezers to gently pick up the Earth Burnham and pop it inside your petri dish. It’s a good idea to pop a cover on this to prevent your worm from escaping. 

Collect your Planarian flatworm by dipping your container into a shallow pond or river. You may need to do this a few times to collect any worms. 

You’ll need your magnifying glass here to take a closer look at the water that you’ve collected to see whether or not the worm is in there.

This is because planarian flatworms can be really small in size, occasionally only 3 mm long. You’ll be on the lookout for a tiny wiggling worm in your water that is black, grey, or brown in color. 

Collecting eelworms is a bit more of a challenge as they are incredibly small and won’t be visible without the use of a magnifying glass.  but if you manage to find an infected crop such as rhubarb or potatoes, you should be able to collect the mealworms using the following method:

Break off some of the leaves of the infected crop, break them into small parts and leave them in a container of water for roughly half an hour. 

 The cluster of mealworms should move down to the bottom of the water full stop.

As you pour off the water you should be left with a small cluster of mealworms at the bottom of the container that you can pop into your petri dish along with a small amount of your water. 

What Do You See?

Now that you have collected all of your specimens, it’s time to have a look at them under your magnifying glass! Let’s look at these three samples in greater detail. 

Segmented Worm

With the use of a magnifying glass, you should be able to see the different segments of your earthworm.  make sure you’re under bright lights so that you can see how the segments allow your earthworm to move about. 

In good lighting, you should also be able to see some of the blood vessels and other internal organs of the worm which would not be visible in lower lighting. 

Notice how the head of the body is narrower than the rest of the body segments. 

You’ll also be able to see that there is a distinct segment within the middle of the earthworm that is larger and slightly lighter as well this segment is known as the clitellum.

The clitellum is involved in the reproduction of the earthworm. 

You should also be able to see the hair-like structures that appear on each of the various segments, these are called setae. 

Notice the shape of the body.  It is fully cylindrical. 

Flatworm

Take a look at your planarian flatworm with your magnifying glass. 

It will be hard to see anything concrete with the magnifying glass on the small planarian flatworms as they are usually between 3 and 15 mm long,  you should be able to see that the end of the body is a little broader and the tail is much more pointed.

You should also be able to see eye spots around the head and a pharynx that is located in the central part of your flatworm. 

Roundworm

Use your magnifying glass to have a look at the heel worms as they are significantly smaller.

It’s going to be pretty hard to make anything out with your magnifying glass but you should be able to see that they’re all moving around in a group.

Eelworms are so small that looking under a magnifying glass won’t have nearly the same effect as looking under a microscope. 

Under The Microscope

Now that we’ve got a good idea of what specimens look like under a magnifying glass it’s time to get out the microscope and have a little bit more of a detailed look at the inner workings of these worms. 

With the use of the microscope, we will be able to see a match player anatomy of our different types of worms and see the real difference between the three samples that we have chosen. 

Let’s begin with the earthworm. 

Segmented Worm Under The Microscope

With the use of dissection and a microscope, you’ll be able to view the full anatomy of the earthworm. 

You Will Need:

• An Earthworm in a petri dish
• Microscope
• Alcohol Solution
• Distilled water
• Tweezers

To prepare for this procedure, pop your alcohol solution into your petri dish with your earthworm.  this will kill your earthworm ready for you to examine it under the microscope. 

Once your earthworm is dead, pick it up with your tweezers and place it inside your distilled water. You should be aiming to wash off any excess dirt or layers of mucus and gunk that is on the outer layers of the earthworm. 

Now your earthworm should be ready to place under the microscope. 

Today, we will be using a stereomicroscope to examine the external anatomy of an earthworm. 

1. To do this, you want to place your EarthWorm into another clean petri dish. 
2. On your stereo microscope, turn the revolving tarot to its absolute lowest setting. 
3. Place your earthworm inside the petri dish onto the magnification stage.
4.  look through the eyepiece of your microscope.  turn the knob on the side of your microscope until the image is brought into focus.
5.  adjust the intensity of your light by turning the knob of the condenser. 
6.  Once you have a perfectly focused image of your earthworm move the petri dish around until you find the anterior end of the worm. 
7. Adjust the magnification to get a closer and closer look at the various sections of your earthworm. 
8. You can also do all of the above steps with a live earthworm.  This will give you a good opportunity to observe how the earth moves such as how the body parts contract and how the mouth opens and closes. 
9.  try to feed your Live EarthWorm and record all of your observations. 

What Do You See?

When looking for a Higher magnification you should be able to see the various sections of your earthworm.  and make sure you are viewing each part of it and labeling it accordingly.  You should be able to see the larger genital pores on the end of the worm, the settee, or that tiny hair bristles, and be able to see how the surface of the worm changes as you move further down its body. 

Dissection

To have a closer look at the internal structure of your earthworm,  you want to dissect your dead earthworm. 

You Will Need:

• Small dissecting pins
• Forceps
• Microscope
• Tiny knife for dissecting
• Dead earthworm
• Disinfected tray

To dissect your dead earthworm, place it on your dissecting tray. 

use your pins to secure each end of your earthworm. this will make sure that it does not slide around as you are inspecting it during dissection. 

Use your dissecting blade or scissors to very carefully cut a small opening below the clitellum of the earthworm.

Once you have made your cut, slide the blade downwards to cut the layer of the epidermis in a straight line from the head to the end. 

Use your forceps to lift the skin in from the sides of your earthworm and pin it to the sides of your trays with several pins so that you can see the internal anatomy of your worm. 

Use your microscope to identify some features of the internal Anatomy you should be able to see the Arches of the heart which are five Loops surrounding the esophagus in the worm. 

The intestines should be visible as a long tube running through the body and behind this tube should be the central nerve cord. 

Planarian Flatworm Under The Microscope

To view Planarian flatworms, we recommend you take a slightly different approach!

You’ll want to keep your worms in one place, so we recommend you use some vaseline on your preparation slide so that they stay secure whilst you are looking at them through the microscope. 

You Will Need:

• Glass Slides and cover
• Agar
• Vaseline
• Compound microscope
• Water

1. Add hot agar to your glass slide.
2. Flatten the agar with another slide. 
3. Once set, remove the top slide and add a drop of water to your agar. 
4. Place your flatworm onto the drop of water and secure it with a vaseline-coated coverslip, being careful to not crush your worm.

What Do You See?

Use your compound microscope to observe your worm. You should be able to map out every part of your worm and focus your microscope as you have for the previous specimen. 

Whilst Planarian flatworms are usually too small to dissect, especially for a beginner, you should still be able to identify all of the parts of its body.

Notice its sensory structure, the way that it eats food and processes it, the pigmentations in its skin that are sensitive to light, and the flattened shape of the body. 

Roundworms Under The Microscope

As eelworms are so much smaller, you will have to use a much higher magnification on your compound microscope to see them with any clarity. 

Use much the same process as you have for the previous two worms. 

1. Use a dropper to collect your worms that should be sinking to the bottom of your collected water jar. 
2. Place two drops of the worm-filled liquid onto your prepared glass slide. 
3. Mount your compound microscope to observe at both a low and higher magnification.

What Do You See?

Now that you have seen all three types of worms, what are the differences between them? What are the similarities?

You should be able to see that the eelworm has a thin, transparent skin compared to the other worms, and you should be able to observe how they move. 

With high magnification, you should be able to see the intestinal tract of the eelworms. How does it compare to that of the flatworm or the earthworm? 

Record all of your findings. There you have it! An interesting look at three similar, yet altogether unique worm varieties.

If you are doing this as a group exercise, compare and contrast your findings amongst the class. Were there any discrepancies? 

Final Thoughts

You should now have achieved your objectives in terms of understanding not only how the anatomy of different worms works, but also the basics of how to use a microscope.

You should now feel more comfortable taking scientific notes, and understand just how varied and amazing life is on this planet, even in such a small subsection of species such as worms! 

We hope this has inspired you to look into more small experiments and explore the wildlife and world around you!

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