Category: 2nd Semester

8 Most Useful Bill Nye Videos To Watch

-Even if you are in college.

Bill Nye the Science Guy hasn’t produced new episodes since the end of Season 5 in 1998, but the show’s namesake host remains active in the promotion of science – and many of his videos remain outstanding content to watch even if you’re in College (or beyond).

Here at Biology Junction, our focus is on our own namesake subject, and that’s what this list focuses on – but for those of you who came here for a more general list, we’ve also included a few non-Biology videos down at the bottom. These videos are helpful regardless of what type of science you’re interested in, so everyone should take a look at them.

How We Chose These Videos

What good is a list without an explanation of how we made it? It wouldn’t be good science if we just threw it up here! Truth is, though, creating this list wasn’t very hard. First, we narrowed our list of sources to the best selections of Bill Nye videos – his classic show and the more-recent Greatest Discoveries series.

Next, we considered how useful each topic is to know. For students studying biology, it does no good to dive into topics more advanced than you’re ready for. Fortunately, most of Bill Nye’s videos are accessible even to beginners and provide a strong foundation for the topic. This ended up being a minor concern, but we were determined to go through the process.

Finally, we checked for the availability of videos. It doesn’t help to be told to watch a video if you can’t find it. A simple search should be enough to locate any of the videos on this list. If that fails, you should be able to get them from your library or preferred streaming service. We had a preference for videos that are freely available since budgets can be tight in college, but that didn’t significantly impact this list.

For our non-Biology videos, we used a similar process. Instead of emphasizing Biology, though, we decided to focus on the foundations of science and the information that’s most useful for everyone to know.

The Best Biology Videos From Bill Nye

Here are our top choices for Biology videos.

1: Biodiversity (S1 E9)

Biodiversity is the 9th episode of Bill Nye the Science Guy, and while it’s not the first to feature a Biology topic, we think it’s easily one of the most important episodes. This video focuses on more than just where things live – it also explains the concept of ecosystems and how important it is to have a variety of living things in each area.

Fish in the habitat

Arguably the most important lesson of this episode is understanding that ecosystems are far more complex than figuring out which living things eat each other. Each part of an ecosystem affects all of the other parts. That’s why we have to be so careful when introducing plants or animals to new habitats – if the ecosystem isn’t ready to handle it, the whole thing could collapse.

A second lesson to focus on is how ecosystems can vary in size – and, in many cases, overlap each other. The Great Barrier Reef has its own ecosystem, but it’s part of the larger Pacific Ocean – and from there, it ultimately affects all life on the planet (even if the impact isn’t obvious).

Understanding biodiversity is critical to understanding biology as a whole. Life does not exist in a vacuum – not unless we put it there, anyway. Environments affect life and vice versa, and if you want to understand why something is the way it is, you have to look at the bigger picture.

2: Cells (S1 E17)

cells

Cells are a fundamental component of life – and even if you think you understand them, it’s good to get a refresher on the topic before you start your studies. The main reason for this is that when we say something “affects an organ”, what we mean is “it affects certain cells of the organ in a particular way”.

For example, if you want to understand why too much alcohol can hurt the liver, you need to look at its impact on the cells of the liver. If you want to heal that liver when you’re done, you have to figure out what will encourage the cells to do that. Cells are the ultimate “micro” topic in biology, making the Bill Nye cells video easily one of the most important episodes for biologists to watch.

3: Food Web (S2 E6)

It’s hard to talk about biology without eventually talking about food – but how things get their food is a little more complicated. Only watch this video after you’ve watched Biodiversity, because that video provides some important groundwork for this topic.

The short version is that a food web describes how each part of an ecosystem gets its food. Ultimately, each living thing gets food either from other living things (like insects, plants, or rodents) or from the sun. Every living creature is ultimately dependent on plants – who, let’s not forget, are often nourished by the uneaten bodies of dead creatures.

(If you’re having flashbacks to a certain Disney movie about a young lion, there’s a reason for that – the Circle of Life, where living things depend on each other, is quite real.) Watch Food Web

4: Plants (S3 E3)

Given how important plants are to the previous video, now’s a good time to get a refresher on what they are, how they work, and what sort of impact they have on our lives. The crazy thing is how plants can synthesize their own food as long as they have sunlight, water, and carbon dioxide – though healthy soil and a few other nutrients certainly help.

plant

Plants are also important for their impact on other aspects of Biology. For example, many medicines are made from plants or plant by-products and affect certain living things in specific ways. Once we understand how something works, we can start figuring out the best way to make use of it.

This is particularly helpful if you’re looking for a job with biology. Most of your work will likely involve seeing how various inputs (types of food, situations, etc.) affect living things, and plants will be a part of that. Studying life alone is a limited topic – but there are endless possibilities when studying the way things affect life.

5: Populations (S3 E19)

Populations are a group of similar living things living in a set area. We often refer to the population of the human race, but we may also talk about the population of a specific city, voting district, or another region.

sunset with population

In biology, the most important thing is understanding the populations of other living things, how they’ve changed over time, and what’s caused them to do so. As you learned in videos like Biodiversity and Food Web, living things all affect each other – and a sudden rise or drop in one population will ripple across the ecosystem and begin affecting other creatures.

There may not be as many fancy names or scientific terms here, but it’s still worth watching this video to ensure you have a good grasp of the fundamentals of biology.

6: Biology – Greatest Discoveries

Finally, Bill Nye’s Greatest Discoveries video on Biology rounds out the best videos on this topic with a look at 13 of the most important discoveries in biology. This includes a discussion on the discovery and impact of:

  • Microorganisms like bacteria, blood cells, and sperm
  • The Cell Nucleus that functions at the center point of most cells
  • Archaea, microorganisms that lack a cell nucleus but aren’t quite like bacteria
  • Cell Division, the process of growth and, in many ways, life itself
  • Sex Cells and how they differ from most other types of cells
  • Cell Differentiation and how different types of cells are made
  • Mitochondria, which are separate from cells but provide a critical function for metabolizing chemicals
  • The Krebs Cycle, which is how protein, fats, and sugars are turned into energy
  • Neurotransmission, which centralizes the body’s ability to control itself
  • Hormones, which are far more complicated than teenage urges
  • Photosynthesis, a process where light is turned into chemical energy
  • Ecosystems, a quick look back at larger ecological units
  • Tropical Biodiversity, or why warm and sunny places tend to have a much greater variety of life

Together, all of these are important for biologists to know.

The Best Overall Science Videos From Bill Nye

Whether or not you’re focused on biology, these videos are helpful for improving your overall understanding of science and are worth watching at any age.

1: Pseudoscience (S4 E9)

Many things that sound like science but aren’t. These things are often called pseudoscience, and learning how to recognize them is a valuable skill for any scientist. Fortunately, the entire topic can be brought down to a few simple principles.

First, science involves testing claims and ideas. If somebody says something can’t be tested, then it’s not within the realm of science and shouldn’t be treated as such. In those cases, it’s okay to say “perhaps we’ll never know for sure”.

Second, extraordinary claims require extraordinary proof. In other words, the more important your claim is, the more you need to support it with verifiable evidence. As the person making a claim, it is your job to provide corresponding proof. It is not the job of others to demonstrate that you’re right.

Furthermore, your results should be reproducible. Proper science only happens when someone tries to prove you wrong – fairly, of course – and fails to do so. If you repeat an experiment and keep getting results, you don’t have any answers – just more questions to ask.

Finally, you should learn critical thinking. This graphic is especially helpful for that and provides many questions that help you uncover the truth. For example, when presented with a claim, you may want to figure out who benefits from it, what the best/worst case scenarios of it are, where it might be a problem or solution, what might make it unacceptable, why people might need it, and how to approach it safely.

In many cases, purveyors of pseudoscience are simply looking to profit from your ignorance. As a scientist, it is your duty to see past things like that and uncover the truth. Watch Pseudoscience now.

2: Measurement (S5 E17)

Coming in as one of the last episodes ever aired, Measurement is something that honestly should have been one of the first videos they made. Measuring things is critical to the foundations of science as a whole. Proper measurements provide objective, verifiable information using a common set of standards, and it’s impossible to overstate how important this is.

There are a few important things to learn from this video, Measurement.

First, there are many ways of measuring things. You can measure units (members of a population), dimensions (the size of something), time (how long it takes something to happen), effects (what happens), and many other topics.

Second, you’ll learn why things should be measured. It’s not just to expand the amount of information we have, though that’s valuable in and of itself. Instead, measurements help us understand what’s different about two subjects so we can proceed to uncover why and how that difference occurred.

Taken far enough, this can lead to discoveries, such as finding that one person in a neighborhood didn’t get sick because they ate a particular herb.

Measurements are almost never a focus in and of themselves – but they’re a vital part of most scientific activities. If you want to be a scientist, then you’re almost certainly going to do a lot of measurements over the course of your career. That makes this innocent-sounding video one of the most helpful episodes of Bill Nye.

From Water to Land: 10 Amazing Types Of Amphibians

There are nearly 8,000 types of amphibians, including some of the most unusual and exciting creatures found on land and water.

About two million species of animals inhabit Planet Earth. More than that, scientists discover and categorize about 10,000 other new species every year. Animals are broken down into classes which include vertebrates and invertebrates, or animals with or without spines.

Amphibians belong to the vertebrate class along with birds, fish, mammals, and reptiles. All amphibians are cold-blooded, meaning they cannot generate body heat on their own. For that reason, they must rely on their environment to keep them cold or warm enough for survival.

Going further, most amphibians undergo a metamorphosis from a juvenile to an adult form. For example, frogs begin as tadpoles with gills and a tail. As they mature, they develop lungs. Over time, four legs replace most types of amphibians tails.

The Types of Amphibians

Amphibian species include three subgroups or orders. Firstly, there is the Order Anura which includes about 6,500 species of frogs and toads.

Secondly, the Order Caudata or Urodela includes about 680 species of newts and salamanders. Thirdly, Order Apoda or Gymnophiona, includes about 200 species of caecilians.

Frogs and Toads

European Common Frog (Rana temporaria) & European Toad (Bufo bufo): Image CC by 2.0 Generic, by Thomas Brown, via Wikipedia Commons
European Common Frog (Rana temporaria) & European Toad (Bufo bufo): Image CC by 2.0 Generic, by Thomas Brown, via Wikipedia Commons

Frogs and toads typically have short bodies, webbed fingers and toes, and no tails. And, they usually have bulging eyes.

Newts and salamanders

yellow-spotted salamander, an amphibian, on a white background
Spotted salamander -Ambystoma maculatum

Newts and salamanders look similar to lizards and have short legs, skinny bodies, and long tails. Surprisingly, salamanders and newts have the remarkable ability to re-grow lost limbs and tails.

Caecilians

Caecilian: one of the types of amphibian with eggs in wet soil
Presumed Microcaecilia dermatophaga mother with eggs: Image CC by A 2.5 Generic, by Wilkinson M, Sherratt E, Starace F, Gower DJ (2013), via Wikipedia Commons

Caecilians don’t have any legs and resemble worms or snakes. That is because they mostly live underground, or in the substrate under streams. As a result, they have strong skulls and pointed noses to help them burrow through mud and dirt.

Fun Facts About Types of Amphibians

Amphibians are an evolutionary link between water-dwelling animals such as fish and land-dwelling animals such as mammals. Let’s be honest, they are some of the most fascinating animals on Planet Earth.

For example, amphibians have extremely primitive lungs. However, they have thin, moist skin that absorbs limited amounts of oxygen. So, you could say some types of amphibians breathe through their skin.

Another exciting fact about them, amphibians are carnivores and predators. But, they cannot chew their food. So, they swallow their prey whole.

Amphibians are also one of the planet’s most endangered animal species. It is believed that nearly half of the world’s amphibians are threatened species. That’s due to a combination of factors, including habitat loss, pollution, and climate change.

10 Amazing Types of Amphibians

Amphibians include some of the most amazing and unusual vertebrates found on earth. Much like their ancestors, most of them stick close to water.

We gathered a collection of photos of 10 of the most exciting types of amphibians currently roaming the earth, below. Then, we included a brief introduction to each one.

1. Axolotl

The axolotl is a type of salamander that is native to central Mexico. Unlike many other types of amphibians, axolotl larvae do not undergo metamorphosis when they reach maturity. As a result, they retain their gills, and tails, and are entirely aquatic throughout their life cycle.

photograph of an axolotl under wooden structure in a tank - one of the types of amphibian
Courtesy of Instagram – axolotltwins

2. Fire Salamander

Fire salamanders are native to the forests of central and southern Europe. These types of amphibians stay near to ponds and streams, which they rely on for breeding. Another cool fact, they are active both night and day.

photograph of a fire salamander - a type of amphibian
Fire Salamander. Image via Instagram.

3. Golden Toad

The golden toad was native to the tropical mountain regions of Costa Rica, known as montane cloud forests. Sadly, golden toads are one of many types of amphibians thought to be extinct since they have not been seen since 1989.

photograph of a golden toad - a type of amphibian
Golden Toad. Image via Instagram.

4. Green Tree Frog

Green tree frogs are native to New Guinea and Australia. Their colors range from brown to green, depending on the surrounding air temperature. These are one of the most abundant types of amphibians dwelling in trees.

photograph of a green tree frog - a type of amphibian
Green Tree Frog. Image via Instagram.

5. Hellbender

Hellbenders are native to wetlands of Kentucky, Pennsylvania, and Tennessee. However, they are sometimes located in smaller numbers in the surrounding states. Sadly, hellbenders join other types of amphibians on the IUCN Red List of Threatened Species.

photograph of a hellbender - a type of amphibian
Hellbender. Image via Instagram.

6. Luristan Newt

These black and white spotted newts are native to the Luristan Province of Iran. While they look like cows, they are clearly amphibians. The Luristan newt is listed as “critically endangered” on the IUCN Red List of Threatened Species. However, they are currently protected under Iranian law.

photograph of a black and white spotted luristan newt - a type of amphibian
Luristan Newt. Image via Instagram.

7. Poison Dart Frog

The poison dart frog is native to the subtropical and tropical regions of South America. They can also be found in Central America. Bright colored dart frogs are extremely poisonous. However, dart frogs with cryptic or dull coloring have nominal toxicity. In fact, some are not toxic at all.

photograph of a poison dart frog - a type of amphibian
Poison Dart Frog. Image via Instagram.

8. Red-Eyed Tree Frog

The red-eyed tree frog is native to the Neotropical rainforests of Mexico and Central America. In addition to their bulging red eyes, these tree frogs have webbed orange feet and blue and yellow flanks. Luckily, due to their large number, they are listed as “least concerned” by the IUCN Red List of Threatened Species.

photograph of a red-eyed tree frog - a type of amphibian
Red-Eyed Tree Frog. Image via Instagram.

9. Endemic Tailed Caecilian

The endemic tailed caecilian is native to the tropical regions of Sri Lanka. Resembling a giant earthworm, endemic tailed caecilians range in size from 9 inches to nearly 16 inches. Additionally, the endemic tailed caecilian is listed as vulnerable by the IUCN Red List of Threatened Species.

photograph of a sri lankan endemic tailed caecilian - a type of amphibian
Sri Lankan Endemic Tailed Caecilian. Image via Instagram.

10. Tiger Salamander

The tiger salamander is native to the mountainous and lowland regions of the United States and Mexico. Unlike other types of amphibians, they tend to avoid water. Additionally, they can grow to lengths of 12 inches and larger.

photograph of a tiger salamander - a type of amphibian
Tiger Salamander. Image via Instagram.

What We Learned About the Types of Amphibians

We hope you enjoyed our article and accompanying photos of amazing and unique types of amphibians.

You have seen our favorite types of amphibians. Now we want to know about your faves. Using the comments section, let us know any unusual types of amphibians you would like to see included in future articles.

Featured image: A collage of various amphibians CC by ASA 3.0 Unported, by Various Artists: File:Litoria phyllochroa.JPG, File:Seymouria1.jpg, File:Notophthalmus viridescensPCCA20040816-3983A.jpg, File:Dermophis mexicanus.jpg, via Wikimedia Commons

Everything You Need to Know About the Calvin Cycle

The Calvin Cycle occurs during photosynthesis and consists of light independent redox reactions that convert carbon dioxide into glucose. This conversion happens in the chloroplast, or more specifically the stroma of the chloroplast. The chloroplast region is an area between the thylakoid membrane and the inner membrane of the organelle which is typically located in the leaves of plants.

This cycle used to create carbon sugars, mostly, was discovered by Melvin Calvin, Andrew Benson, and James Bassham in 1950 at the University of California. The used radioactive material to trace the pathways carbon atoms took during the carbon fixation step in plant life.

You’ve probably heard the Calvin Cycle called a few other names including the CBB Cycle, C3 Cycle, and dark reactions to name a few.

This process of carbon fixing by plants is essential to all life on the planet. Most new organic growth stems from plants converting carbon to sugars either directly or indirectly. Other plants, or animals, can use these sugars to forms more complex sugars and amino acids when they consume them. It all stems from little plants working day and night to capture light and water.

A Technical Take on the Calvin Cycle

The Calvin Cycle

The Calvin Cycle occurs during photosynthesis and is repeated until it forms a glucose molecule. Photosynthesis goes through two stages to create food and building materials for plants to grow. During the first stage, chemical reactions from light produce ATP and NADPH. The second stage is when the Calvin Cycle takes place. In this stage, carbon dioxide and water get converted to organic materials like glucose. These reactions are called dark reactions which confuses people, but they do not take place at night.

The short explanation of the Calvin Cycle is that it begins with carbon fixation. Carbon dioxide molecules are plucked out of the air to produce glyceraldehyde 3-phosphate. RuBisCO, an enzyme found abundantly around the planet, brings on the carboxylation of a 5-carbon compound and provides a 6-carbon compound that halves itself form two 3-phosphoglycerate. The enzyme phosphoglycerate kinase uses the phosphorylation to create biphosphoglycerate.

Next, the enzyme glyceraldehyde 3-phosphate dehydrogenase uses the reduction of biphosphoglycerate by NADPH. This is called the reduction reactions. Eventually, when the cycle ends, the reactions and reductions produce one glyceraldehyde 3-phosphate molecule per every three carbon dioxide molecules.

That’s a lot of massive words. What that means is the plant uses light and water to convert carbon dioxide into nutrients and oxygen. It takes six turns on the Calvin Cycle for the plant to produce a single glucose molecule. Now that we simplified the process, let’s look at the chemical equation for the Calvin Cycle:

3 CO2 + 6 NADPH + 5 H2O + 9 ATP → glyceraldehyde-3-phosphate (G3P) + 2 H+ + 6 NADP+ + 9 ADP + 8 Pi (Pi = inorganic phosphate)

The Simplified Function of the Calvin Cycle

Simplified-Calvin-Cycle-diagram

How plants create sugar from sunlight, water, and carbon dioxide is complicated as you probably noted from the previous section. However, plants toil away day and night creating glucose, starch, and cellulose so they can grow. The Calvin Cycle plucks carbon molecules right out of the air and creates new plant growth.

The Calvin Cycle is vital to every ecosystem, and it reaches far beyond the plants using it. Plants are the building blocks of all the food in any ecosystem. Herbivores eat plants for energy and growth while carnivores eat herbivores for the same reasons. In the end, everything goes back into the ground and plants start the process all over again.

If plants stopped all their hard work tomorrow, it would only take a few days for animals to start feeling the effects and starving. Herbivores lose their food right away. Carnivores would follow behind the herbivores. Plants make most of the basic building blocks we all need to continue life as we know it. Without their hard work, we’d all be doomed.

While plants are supplying us with the building blocks, we need to continue living, and they help out the environment in other ways. Because the Calvin Cycle depends on carbon dioxide, plants indirectly play a role in regulating carbon dioxide and other gases proven to be harmful to the atmosphere. Plants perform an essential role in helping us clean the air we breathe.

The Calvin Cycle Step by Step

Calvin Cycle step by step

Carbon fixation is the first step. We explained it in brutal technical detail above, but let’s look at it in simpler terms in this section. A carbon dioxide molecule is plucked from the air and combined with a five-carbon acceptor molecule called ribulose-1,5-bisphosphate, or RuBP for short. The result is a six-carbon molecule.

The six-carbon molecule is split in half to form a set of new carbon molecules called 3-phosphoglyceric acid, or 3-PGA for short. The new three-carbon molecules are catalyzed by an enzyme called RuBisCo. This creates the simple sugar molecules the Calvin Cycle needs for stage two. On a side note, because it is used by every plant during photosynthesis, the RuBisCo enzyme if the most common catalyst on Earth. The result of this step is passed on to the next phase.

Step two of the Calvin Cycle is called the reduction step. The 3-PGA molecules created in the carbon fixation step are used in phase two to develop glyceraldehyde-3 phosphate or G3P for short. G3P is a simple sugar. This process uses energy and reactions captured during light-dependent stages of photosynthesis.

This step is called the reduction step because electrons are stolen from molecules created during photosynthesis and given to our new sugars. In chemistry, when you take electrons from a molecule, it’s called a reduction hence the name of this stage. Technically, the electrons are donated and not taken. Taking electrons by force is called oxidation, and that’s not what happens in this stage.

At this point, our plant has created sugar it can store for a long time and use for energy. Anything that eats this plant gets to take advantage of these sugars as well including humans. The plant may choose to use these stored molecules to form new plant materials or repair itself, but that’s not part of the Calvin Cycle so we won’t get into it. This is the end of the sugar-producing phase of the Calvin Cycle.

The final stage of the Calvin Cycle is called the regeneration step. Some of the G3P are held back and not used to make sugars. Instead, they are used to revitalize the five – carbon compound the Calvin Cycle needs to start the process over again. It takes six carbon molecules to make glucose, so plants have to go through the Calvin Cycle six times to make one glucose molecule.

Once the plant has completed this cycle six times, the Calvin Cycle ends and begins again. So, technically, the Calvin Cycle is all three steps done six times each. Plants repeat this process over and over during daylight hours. At night they continue to work making various compounds that don’t require light. This makes plants the most efficient lifeforms on the planet.

Bonus Information About Plants and Their Internal Food Factories

plants

We usually consider waste products bad or at least not edible. However, we need the waste materials plants to produce to survive. An essential waste, or by-product, plants produce is oxygen. While plants are using water and carbon dioxide to make sugars, they release oxygen into the air around them as a waste product.

The delicious fruits and vegetables we all enjoy get most of their flavor from the carbon sugars plants store for energy. From the crunchy stalk of the celery plant to the succulent meat of the peach, plants developed all using just carbon dioxide, water, sunlight, and a few minerals leeched from the soil. I think we can assume these tasty treats are little gifts from the plant kingdom.

The tiny organelles called chloroplasts on the surface of a plant’s leaves can move. Ok, they can’t move individually, but in many plants, they can turn the leaf, so it gets better exposure to sunlight. These plant-based solar cells help capture sunlight so being able to point yourself in the sun makes sense. Some plants take it to another level and bend their stalk or branches to help reach the sunlight.

Some Final Notes

photosynthesis diagram

The fantastic plants we ignore all around us are vital to our survival. They use energy from the Sun in little energy reactors called chloroplasts to do all sorts of cool things. If you glance at the bigger picture and oversimplify it, plants take light from the Sun and turn it into carbon sugars they can store for long periods of time. We could call them solar powered batteries if we want to be humorous about the process.

Plants pitch in and help everywhere they can from cleaning the air to enriching the soil they grow in for the next plants. Plants give us so many things from apples to steak. Without plants toiling away at the bottom of the food chain, nothing in the top of the food chain could survive. Every food we consume comes from plants either directly or indirectly.

Your Guide To Your First Earthworm Dissection

Earthworms play essential roles in many ecosystems. They help introduce oxygen to the soil and mix it up. As they tunnel through the ground, they enrich the soil and push it toward the surface where it’s easier for plants to get to the nutrients. You can see the organs that help these worms do their jobs by dissecting an earthworm.

Safety First

woman showing earthworms

Safety is critical in all aspects of our lives. It may seem trivial in a controlled environment like a school biology lab, but it’s not, and all safety rules should be followed. They are in place to protect you and your classmates, so don’t skip any regulations just because you think it will be ok or those rules don’t seem to apply to your circumstances. The basic common-sense rules are:

  • Wear safety gear when necessary like goggles, gloves, and aprons.
  • Most preserved specimens contain formaldehyde, so wash them first.
  • Do not play with lab equipment or instruments such as scalpels and scissors.
  • Do not eat any parts of your specimen. Yes, there is an apparent reason for this rule.

Your lab should have the rules and safety measures available plus your instructor will go over them with you. Don’t assume the only rules are the ones we list here. The type of lab and type of specimen determine the rules. Ask for a copy of the rules if you don’t see one posted in the lab. Your teacher should be close by most of the time to help you guide you as well.

Always wear safety goggles and gloves. If you have to carry a sharp instrument, hold it with the pointed end pointing down and away from your body. Don’t rush or run while holding a scalpel or scissors. Never carry a knife or scissors by any part other than the handle. Scalpels are razor sharp, and it only takes a split second for them to cut you open.

Keep your station clean and tend to any spills immediately unless they pose a breathing hazard. Dispose of any blades, gloves, aprons, and specimens according to the established rules in your lab. Your teacher will probably explain all the rules to you, but don’t wait to ask if you aren’t sure what to do. Teachers are there to help educate you and keep you safe.

Earthworm Dissection Guide

earthworm dissection

Earthworms are great for helping you understand simple organisms and basic anatomy. They’ll help you get a grasp on lab safety before you progress to larger specimens like pigs or frogs. As a bonus, they’re small and soft, so handling them is much more comfortable as well.

The first step is to examine the exterior of the earthworm. Earthworms are segmented works, so they look like a long stack of small rings. They don’t have a head or any limbs, but they do have a fascinating exterior anatomy to study. The anterior end of the earthworm is a little fatter than the posterior. When you locate the anterior end of the work, pin it to the dissecting pan or tray.

Earthworms are annelids which means their bodies are composed of multiple ring-like sections or segments. This part may not be on your teacher’s list, but it’s always interesting to count the segments while you study the exterior anatomy of the earthworm. While you count, notice the small setae on the ventral surface. These little bristles help the worms move through the dirt with ease.

Each segment along the worm’s exterior has small pores. These pores excrete the sticky film you find when you run your finger along a live worm. You may need a magnifying glass or small microscope to see them. It depends on the size of your earthworm specimen and your eyesight as well.

From the anterior end of the worm, count your way down to segment fourteen. Typically, this is where the oviducts are located. The oviducts release the eggs when the worm reproduces. The exciting part is the next segment after the oviducts; it contains the sperm ducts. Earthworms have both male and female reproductive organs.

Further down the worm at segment 31 is the clitellum. It secretes a sticky mucus that binds two earthworms together while the mate. It develops a cocoon to hold the eggs and sperm after mating is finished. Earthworms are simple worms, but fantastic at the same time. Their exterior anatomy is fascinating to study.

Earthworms are hermaphroditic which means they have both female and male reproductive organs. Eggs come from the ovaries inside segment fourteen, sometimes thirteen. It can be hard to count the segments on small worms. Worms have testes which can form in segments near the oviducts. Study these segments and see if you can find the reproductive organs on your specimen.

When worms mate, they get stuck together briefly to help keep the reproductive organs aligned. Sperm from both worms travels into the other worms seminal receptacle. The clitellum creates the cocoon which moves along the outside of the worm to collect the semen and the eggs. The eggs are fertilized outside the worm in the cocoon.

By now, you should have a good understanding of the exterior anatomy of your earthworm specimen. Remove the pin from the anterior end of the earthworm and place it on its ventral side, then put the pin back in the anterior end of the worm. The ventral side of the worm is a little flatter than the dorsal side, and it may be a lighter color.

Carefully and slowly make a shallow incision using your scalpel from the anterior end of the work to the clitellum. Never cut toward your body or fingers. Be extra careful and keep the incision shallow, so you don’t cut into the worm’s digestive system and internal organs. Use your forceps to spread the worm open and pin the sides of its body to your dissection pan or tray.

The inside of the worm should be exposed now. You may want to lightly sprinkle water over the worm to keep it from drying out while you study the inside of it. The interior part of the walls is called the septa. See if you can tell the difference. If possible, ask your teacher to point them out and help you see the different layers.

Now, the internal digestive organs should be exposed and available for study. Starting with the mount on the anterior end of the worm, locate the organs. The first organ you see is the pharynx. The worm’s esophagus protrudes from the pharynx. About halfway down your incision are the crop and gizzard. Skip the other organs for now and find those two.

The crop is essentially a stomach. It stores food until the food is moved to the gizzard which grinds it up. The food leaves the gizzard and goes into the intestine, much like it does in humans, and travels to the anus. Along the way, the worm’s intestines absorb nutrients from the food the gizzard crushed and ground up. Earthworms don’t eat dirt. The consume organic materials found in the soil.

Make your way back up to the crop. If you look above the crop on the anterior side, you’ll find five pairs of aortic arches. This is the worm’s version of a heart. The hearts are located around the esophagus, and they connect to the dorsal blood vessel. That’s the worm’s version of an artery. Most earthworms can take direct damage to half their aortic arches and live.

Move your attention back to the pharynx at the anterior end of the worm. Locate the cerebral ganglia beneath the pharynx on the dorsal side. You may need to use your forceps to move some organs around to get a good look at it. The ventral nerve starts at the cerebral ganglia and runs the length of the worm. It may be hard to see if it is too small.

They are simple creatures speaking purely on their anatomy, but how their bodies and mating works are truly amazing. If you have time, go back over this tutorial again and study the worm longer. When you finish exploring, make sure you clean your workstation and dispose of your specimen correctly. Dispose of your lab gear according to the lab rules. Wash your hand thoroughly with soap and water.

Some Final Notes

earthworm

Earthworms are vital to the health of our soil. The improve drainage, help stabilize the land, and add nutrients to the ground. Worms feed on organic materials they find in the dirt. Their bodies use the nutrients they need and deposit what’s left back into the soil as waste. Fortunately for plants, that waste is usually nitrogen-rich along with other nutrients plants need to grow.

Their worm tunnels help loosen the soil which aids plants in root development. We could go on and on about the benefits of earthworms. If you follow our guide to dissecting earthworms and read our interesting facts along the way, we’re sure you’ll be able to dissect an earthworm specimen safely. You may even appreciate these simple creatures a little more when you are done.