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

Types of amphibians: European Common Frog (Rana temporaria) & European Toad (Bufo bufo) on a grassy patch of soil
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): Image CC by 2.0, by Brian Gratwicke, via Wikipedia Commons

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
Types of amphibians: Axolotl. Image via Instagram.

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

8 Websites with the Best AP Practice Exams

 High school is a challenging time in everyone’s life. And for students enrolled in AP courses, the end of the year is particularly challenging. As high-achieving students gear up for long exams that offer the potential for early college credit, many students are searching high and low for reliable study materials.

One favorite way to practice for an important exam is by taking practice exams. But finding high-quality AP practice exams is challenging. That’s why we curated this list of websites for you. Whether you’re looking for AP Biology practice exams or one for AP Art History, these websites will help you in your quest for a good score.

Why You Should Take a Practice Exam

The best way to gauge how ready you are for an exam is by taking a practice test. While its best to drill yourself with a wide variety of study materials throughout the year, use of a full-length practice test will help you to prepare for the exam in a whole new way. In addition to helping you study, taking a practice exam can offer the following benefits:

  • Enables you to acclimate to the test format.
  • Relieves unwanted test anxiety.
  • Familiarizes you with test content.
  • Offers an opportunity to customize your study plan.
  • Gives testers a sense of readiness.

Practice exams are a helpful tool for getting yourself in tip-top test shape. But don’t forget to apply the knowledge you gain from taking practice tests. For example, if you come across the material in the practice test that you don’t understand, bring it up with your teacher as soon as possible.

girl studying

Source: Pexels.com

Below you’ll find a list of websites that offer AP practice exams in one format or another. Not all of them provide full-length tests, but all of them will help you get ready for your AP exams. Keep in mind, that AP tests are different each year and the practice questions you find online won’t necessarily be the ones you encounter on your exam.

8 Websites with the Best AP Practice Exams

College Board

image by: College Board

If you’re looking for a good starting place when it comes to mastering an AP exam, start with the official College Board website. There are many useful resources available on this website for students who are preparing for any of the AP Exams. In addition to study materials, the College Board website provides all of the information students need about the AP exams.

In addition to general information about each of the AP exams, the College Board website also offers sample questions for curious students. While a limited number of multiple choice sample questions are provided, a wide array of free response questions are typically available. Also, you’ll find a handful of student responses for comparison.

While this website doesn’t provide full-length practice exams, it is a great starting place. College Board is the official company behind all of the AP exams, and therefore the study materials they provide will be most like the AP tests.

APPracticeExams.com

image by: appracticeexams

This website is an all-purpose study site from students preparing for AP exams. From AP Biology practice exams to class notes on Statistics, this website has a little something for everyone. It’s also worth noting that all of the resources on this web page are provided free of charge.

Unlike some websites that maintain their database of practice materials, AP Practice Exams provides links to the best free AP practice exams online. Students love using this site because it is easy to navigate and understand. Parents like this website because all of the materials are free.

While you can find a lot of resources through this web page, it does have its limitations. More specifically, the site is not backed by any testing or tutoring service. This drawback means that you’re on your own with the resources provided. However, for those who are self-driven, this site can be a treasure trove of information.

Also, it’s worth noting that the website is very low-key and doesn’t feature many stunning visual features or modern conventions. However, because the resources are all free, it’s a good option for many.

Albert

image by: albert

Albert is a study and test-prep website designed to help students get the most out of the learning experience. Unlike the sites already mentioned above, the resources available through this website are not free of charge. However, they do offer a comprehensive program for preparing for many of the AP exams.

Pricing for the materials on this website varies by subject area, but for the most part, you can expect it to be relatively affordable. Unfortunately, it doesn’t seem that there are any concessions made for students who can’t afford the costs associated with using Albert.

Albert provides a variety of study materials including practice multiple choice questions, practice free response questions, and at least one full-length practice exam. Additionally, there are numerous study tips and testing tricks to help students make the most of test day. Albert also offers an overview of the core concepts that are tested in each subject.

This website features an attractive and easy-to-use interface that simplifies the study process. However, the fact that you must pay to use these study materials means that many students won’t be able to take advantage of this program. All in all, this is a good website for students whose parents have a little extra cash to spare.

Get A Five

image by: getafive

Get A Five is a web-based tutoring program that is available to students and teachers free of charge. However, unlike some other websites, this one is somewhat limited in scope. But, if your AP class is available, we highly recommend taking advantage of this valuable resource.

Unlike other programs, Get A Five offers a virtual study room, a diagnostic test, practice tests, and video-based lessons. Each program available in this online resource is customized to provide users with the ultimate learning experience.

Despite being limited to the few materials available, this website is an excellent resource for AP students in the classes offered. And, for a small fee, you can have your practice free response questions hand graded. We love that this resource doesn’t cost anything to use, but provides excellent value nonetheless.

Get A Five currently offers four courses for students preparing for the AP exam period. The subjects offered include AP Calculus AB, AP Biology, AP US History, and AP World History. While this selection is limited, it’s worth checking back from time to time to see if new courses become available later on.

High School Test Prep

Highschooltestprep

High School Test Prep is another free resource available for students preparing to take an AP exam. The materials available on this website are relatively limited but can prepare you for the general idea of how the test will be. However, it’s worth noting that this resource does not provide full-length exams. Also, it only covers multiple choice questions.

To help students understand the subject area they are testing over, each multiple choice question on this website gives a brief explanation of the correct answer. And while we wouldn’t recommend relying on this website alone, it serves as an excellent way to see where you stand.

After reviewing the materials on this website, you’ll be better prepared to formulate a study plan that will adequately prepare you for your upcoming test. Once you’ve studied the areas that are more difficult for you, use one or more of the other resources listed here to prepare yourself even more.

logo

image by: study.com

Study.com offers students a variety of materials for preparing for several different AP exams. They even provide several short practice exams to help you evaluate where you stand concerning the test you’ll be taking later in the school year.

In addition to the short practice tests they offer, study.com also offers test prep services. However, it’s worth noting that these services are not free of charge. Information on pricing is not disclosed without starting a “free trial” so explore these options carefully.

We like that there are several free practice tests available, but the lack of clarity when it comes to plans and pricing seems a bit dubious. Still, if you’re willing to spend a little money, it may be worth it to explore this option.

If you feel that you still need extra practice after thoroughly searching through these websites, consider visiting your local library. There, you may find practice books that contain additional practice questions or exams.

Keep in mind, not all study resources are free, and you should be extremely cautious when choosing how to spend your extra money. Also, always use caution when you have to input a credit card number online. And never purchase online materials without your parent’s permission.

With the resources listed above, you should be well on your way to finding the practice exam that’s right for you. Also, don’t forget that practice exams are only part of the study equation. Remember to brush up on necessary vocabulary and time management strategies as well.

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.