classifying living things

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Classifying Living Things

1.1 Welcome

Notes:

Welcome to “Classifying Living Things”, an interactive science tutorial for students like you.


1.2 Meet Tony the Taxonomist

Notes:

Hey there, glad you could join me. My name is Tony and I’m a taxonomist. I love to study living creatures. In fact, it’s what I do in my job. I research and classify all living creatures or organisms - as we scientists say. Ah, yes a taxonomist is a biological scientist. Not all scientists do or study the same things! The specific branch of science that I work in is called taxonomy. Taxonomy is the branch of science concerned with the classification of living organisms.

A big part of my job is figuring out how living organisms on Earth are similar or different compared to each other and how to group organisms into categories.


1.3 Objective

Notes:

In this tutorial today, I’ll teach you to describe how and why living organisms are classified. This will include plants, animals and microorganisms.


1.4 Practice 1

Notes:

Let’s test what you already know about sorting organisms before we move on. Classifying is similar to sorting objects or organisms into groups based on characteristics they have in common. See if you can select the correct groups for the organisms on the screen by clicking, dragging and dropping them into their correct location. After you choose all of your groups, click the SUBMIT button below and feedback will appear to let you know how you did.

Drag Item Drop Target

turtle Reptile

fire salamander Amphibian

seedling Plant

shark Fish

dolphin Mammal

flamingo Bird

Feedback when correct:

Great job. You’ve sorted all the organisms on the screen correctly. You’re already showing you

know the basics to grouping organisms!


Feedback when incorrect:

Here is the correct arrangement, classification is all about organizing organisms by shared

characteristics. While some might be easy to identify, others can be quite challenging.


1.5 Prior Knowledge: What You Need to Know About Animals

Notes:

Before we get started, there are a few things we should review so you can be successful in following me through this tutorial. Let’s think about the ways we already know to classify living things, like you just did on the last slide.

We know there are animals and plants, and that they are different. We’ll take a look at animals first. Animals can be divided into many different categories. One category is whether or not animals have a backbone. Animals with a backbone or spine are called vertebrates, like the bird, goldfish and monkey. Animals without a backbone or spine are called invertebrates like the crab, worm and beetle.

We can also classify animals by how they give birth to their young. Some animals, such as birds and frogs, lay eggs. Other animals, such as most mammals, give birth to live young. An example would be elephants, cats, and dogs.


1.6 Prior Knowledge: What You Need to Know About Plants

Notes:

Plants can be divided into many different categories as well. Some plants are vascular, which means they have tubes that carry water and nutrients from their roots to the stems and leaves, like this rose bush. Some plants are nonvascular, which means they do not have these tubes for transport and so they must grow close to the ground, like this moss.

Other plants have flowers as part of their reproductive process, such as these wildflowers. There are also plants, take the fern for example, that are non-flowering and reproduce with spores.


1.7 Why Do We Classify?

Notes:

Have you ever observed a roly-poly? You know-- the little bugs that will roll into a ball if they feel threatened? Well have you ever seen a wood louse? What about a sow bug or a pill bug? Guess what, these are actually ALL common names for the SAME organism. This can happen with plants too. Have you ever picked a dandelion to blow the seeds and make a wish? Well, some people might call this same plant a blowball, a lion’s tooth or a cankerwort. Wow, that could get confusing! Think of how complicated it would be if every person had their own name for each living organism on Earth! Well it used to be this way, and it was confusing! But don’t worry, scientists have developed systems for classifying living organisms to avoid this confusion. There are many classification systems, but we’ll focus on only one in this tutorial today.

Another reason we classify organisms is because it is a good way to look at differences and similarities in organisms found throughout the world. We can observe patterns and study changes in organisms to see how they may or may not be related.

Scientists predict there are over 10 million different species on the Earth. Scientists, including biologists and taxonomists, try to study every known living organism on Earth. Think about how difficult this would be if a standardized or consistent way of organizing and representing these organisms did not exist!


1.8 Practice 2

Notes:

Read the explanations on the screen and choose the best option to explain why scientists use classification systems to organize organisms.

Correct Choice Feedback

No To keep a list of all organisms currently

living on Earth.

Try again. Classification systems are

used to keep a list of organisms but

there is more than that.

No Because animals need to know which

groups they belong to.

Try again. Animals don’t need to know

what group they belong to. Only

humans are really interested in that!

Yes To note similarities and differences in

different organisms and to avoid

confusion when studying them.

Excellent! Scientists use classification

systems to organize organisms to avoid

confusion when studying them.

No Because animals needed to have similar

names, but plants could have multiple

names without causing confusion.

Try again. Classification systems are

used for all living organisms; including

plants and animals. There are


Correct Choice Feedback

thousands of plant species on earth to

classify.


1.9 Your Challenge!

Notes:

Okay, now I’d like to present you with a challenge! I’m going to have you study how taxonomy works. We are going to figure out how closely related the Florida panther from the continent of North America is to the Bengal tiger, predominantly from the continent of Asia using Linnaeus’s system of classification to help you. Let’s see how well you do!


1.10 Do Cells Matter? Where Do We Start?

Notes:

Let’s think about what the Florida panther and the Bengal tiger have in common with each other and how closely they might be related. I’m not just talking about the fact they both have four legs, both are mammals, or they both eat meat. Those are pretty specific common traits. Let’s look at how all life is sorted but way down at the most basic level. We are going to zoom way in and look at the cellular level. Remember that all life is made up of cells. Cells are the basic unit of living things. Even the smallest organisms are living with just one cell. That even includes bacteria!

Both the tiger and the panther are made up of many complex cells; trillions in fact. Observing their cells is the first way we will look to classify these organisms. There are three large, basic categories that were developed to classify organisms on a cellular level: these are called domains. The three-domain system was developed by a scientist named Carl Woese. In his study of living organisms, he realized that organisms differed by the amount of cells they had and the complexity of their cells. Two of the categories he developed classified single-celled organisms. They are the Domain Archaea and the Domain Bacteria. To be in either of the domains means that the organisms are unicellular and they do not have membrane bound organelles or a membrane bound nucleus. We call these cell types prokaryotes.

Members of the Domains Archaea and Bacteria are also microscopic. They are small and only made up of one basic cell. In fact, there are more species of living things made up of one cell than there are made up of many cells. Examples of these organisms would be various forms of bacteria. Some of these bacteria you might be


familiar with and not even know it! Do you like yogurt? There are bacteria that help make yogurt. Have you ever had strep throat? Well, a bacteria made you sick with strep throat.


1.11 Do Cells Matter? : Eukaryotic Cells

Notes:

The other domain classified organisms with more complex cells, like the Florida panther and Bengal tiger. They named this domain Eukarya and all members have complex cells. Eukaryotic cells have membrane-bound organelles and their DNA is enclosed in the membrane-bound nucleus. Examples of some of the organelles they contain are mitochondria, endoplasmic reticulum, and chloroplasts-for plants. Plants, fungi, protists, and animals are all found in the Domain Eukarya.


1.12 Practice 3

Notes:

Click, drag and drop each organism into the correct domain on screen.

Drag Item Drop Target

Bengal Tiger Domain Eukarya

Florida panther Domain Eukarya

Helicobacter pylori bacterium Domain Bacteria

Escherichia coli Domain Bacteria


Great job. You remembered that tigers and panthers are made up of complex cells and belong in

the Eukarya domain. The Helicobacter pylori bacterium and Escherichia coli are both forms of

bacteria and belong in the Bacteria domain.


Nice try. The tigers and panthers are made up of complex cells and belong in the Eukarya

domain. The Helicobacter pylori bacterium and Escherichia coli are both forms of bacteria and

belong in the Bacteria domain.


1.13 How Do We Classify?

Notes:

Scientists classify living organisms so they can easily study and understand how they live, what behaviors they have or share, their eating patterns, and even the way they have changed over time. After being placed in one of the three domains, the classification method widely used with biologists is the Linnaean system of classification, named after the scientist Carolus Linnaeus who developed it in the 18th century. During his lifetime, Linnaeus collected over 40,000 different plants, animals and shells. He began to recognize a need to have a standard method for grouping and naming living organisms and so he created his classification system. The Linnaean system of classification groups living organisms into a hierarchy, meaning they are grouped into levels. This system of classification provides a standardized approach to naming, ranking and classifying living organisms.

There are seven levels to this system. There are six kingdoms that all living organisms can be placed in. Kingdoms are broken down into phyla or phylum for singular. Phyla are divided into classes, which are divided into orders, and further divided into families and genera or genus for singular, and then lastly into species. The Linnaean system was effective at establishing a standardized or consistent method for classifying living organisms based mainly on physical characteristics. Today scientists know much more about DNA and molecular biology, which has helped classify living organisms more accurately to provide a clearer picture of life on Earth. The Linnaean system is important and influential even though scientists have changed and altered it many times as new discoveries have been made. It is still relevant because it provided the first classification system of its kind.


1.14 Linnaean System of Classification

Notes:

Some people use mnemonics, which are memory devices to help remember large pieces of information. There is a mnemonic device used to help remember the levels of classification in Linnaeus’s system. The first letters of each word in the following sentence match the first letters of the classification system. You might use King-Phillip-Came-Over-For-Good-Spaghetti to help you remember the order of Kingdom-Phylum-Class-Order-Family-Genus-Species. Remember that domains weren’t included here because the Linnaean system of classification starts with kingdoms.


1.15 Classifying Plants & Animals

Notes:

I’m going to focus on classifying plants and animals now. Plants and animals are multi-celled complex organisms so the examples I review with you next will be part of the…any guesses… Domain Eukarya. There are four common kingdoms in the Domain Eukarya - Protista, Fungi, Plantae and Animalia. We’ll only be talking about two in this tutorial; the Kingdoms Plantae and Animalia. Discussing these two kingdoms will help you get closer to figuring out how closely related the Florida panther is to the Bengal tiger. There are many more categories under each of the Linnaean system of classification levels. We could be here a long time classifying living organisms, so I’ll focus on one example for the Kingdom Plantae and one example for the Kingdom Animalia. You’ll notice that the words ‘Plantae’ and ‘Animalia’ sound a lot like ‘plant’ and ‘animal’. These are just the versions of the words in the Latin language which is the language used by taxonomists. We’ll dive into this on the next slide.

Additionally, you’ll notice that species is the last level of Linnaeus’s system. Species is defined as the largest group of organisms capable of interbreeding and producing fertile offspring. This means animals of the same species can mate and have babies and their babies can have babies too. For example, I might have a black lab dog, and you might have a golden retriever dog. These two dogs could mate and have puppies with features from both of the parent dogs. Their puppies could then go on to have puppies of their own. As a result, we can call the black lab and the golden retriever the same species. We don’t know if our challenge animals, the Florida panther and the Bengal tiger, could mate with each other yet, so we need to gather more information.


1.16 Classifying Plants

Notes:

I’ll start by classifying an organism in the Kingdom Plantae. Remember that kingdoms are divided into many phyla and for this example we’ll study the Phylum Magnoliophyta more closely. This phylum is composed of plants that have leaves, stems, roots, and flowers. The plants in this phylum also have seeds with a shell-like coating. These seeds are easily spread by wind, water, or animals so more plants can grow.

This phylum is divided into two classes; I’ll use the Class Magnoliopsida for our example. Have you noticed as we move down each level in the Linnaean system of classification fewer and fewer organisms are showing? The whole point of this classification system is to show as you get closer and closer to the species, fewer organisms will have characteristics that are in common. The more classification levels shared, the closer organisms are related to each other. Are you seeing how this classification system will help us relate the Florida panther and the Bengal tiger yet?

The Class Magnoliopsida is again divided even further into about 27 different orders. We’ll look at the Order Asterales for our example. This order is composed of ‘ray flowers’, which are flowers with flat petals that extend from a central point, like the sunflower. In this order there are 11 different families. I’ll use the Family Asteraceae for our example. From here the family is further divided into the genus and species.


The names in these two levels signify another addition to the science world from Carolus Linnaeus. He created a unique naming system for classifying living organisms using his system called Binomial Nomenclature. This is a two part naming system where the first part of the name identifies the genus of the organism and the second part identifies the species. The genus and species is referred to as the scientific name for an organism. The scientific name uses Latin words to identify the organism. The genus and species will always appear italicized which means it is slanted, or underlined when written. The genus will always be capitalized, and the species will be lowercase. So if we continue with the Genus Helianthus and the Species annuus can you guess the scientific name using this system for the common sunflower?


1.17 Practice 4

Notes:

Try to recall the information from the last slide and choose the correct scientific name for the common sunflower. Use the labeling on the screen to help you.

Correct Choice

Yes Helianthus annuus

No Annuus Helianthus

No Helianthus

No annuus


Good job. Helianthus annuus is the correct scientific name for the common sunflower. It is the

Genus Helianthus first and the Species annuus second.


Nice try. Helianthus annuus is the correct scientific name for the common sunflower. It is the

Genus Helianthus first and the Species annuus second.


1.18 Classifying Animals

Notes:

Let’s classify a living organism in the Kingdom Animalia now. Hmmm…if only I could think of an idea for a living organism to use…Oh wait, I know! How about us? Yes I said us, meaning humans! This is a great example to use. Wouldn’t you like to tell your family tonight that you know how humans are classified? Excellent!

So all humans are in the Kingdom Animalia which is divided into many phyla just like plants, but for our example we’ll use the Phylum Chordata. One common characteristic for most of the animals in this phylum is the presence of a backbone. Check to make sure you have your backbone today… just kidding!

From here, the Phylum Chordata is divided into several more classes. For humans it breaks down further into the Class Mammalia or mammals. Remember these levels are named in Latin! So all the animals that are mammals share common characteristics.

This divides down further into the Order Primate. A common characteristic shared by primates are having forward facing eyes. Think about how difficult it would be to complete this tutorial if both your eyes were on the sides of your head! Good thing they are facing front! From here primates are divided into the Family Hominidae. This group includes the great apes, like orangutans, chimpanzees, gorillas, bonobos and humans. Dividing even further we have the Genus Homo. An interesting fact about this genus is that humans are the only remaining living organisms in this level, all others are extinct! Lastly humans are divided into the Species sapiens


where you and I are classified along with every other living human being on Earth. Now let’s see if you can identify our scientific name on the next slide!


1.19 Practice 5

Notes:

Let’s use our knowledge about classification and binomial nomenclature to choose the correct scientific name for all human beings. Click on the scientific name for humans. Use the labeling on the screen to help you.

Correct Choice

Yes Homo sapiens

No Sapiens Homo

No Homo

No sapiens


Good job. Homo sapiens is the scientific name for all human beings. It is the Genus Homo first

and the Species sapiens second.


Nice try. Homo sapiens is the correct scientific name for all human beings. It is the Genus Homo

first and the Species Sapiens second.


1.20 Practice 6: Matching Organisms

Notes:

Now that you understand how this classification system works, let’s try a more challenging question. Which organism is most closely related to the green anole- a type of lizard: an alligator, a rose, or a boa constrictor? Remember that the more levels of the Linnaean system of classification the organisms have in common the more they are closely related.

Correct Choice

No Alligator

K - Animalia

P - Chordata

C - Reptilia

O - Crocodilia

F - Alligatoridae

G - Alligator

S - mississippiensis

Yes Boa Constrictor


Correct Choice

K - Animalia

P - Chordata

C - Reptilia

O - Squamata

F - Boidae

G - Boa

S - constrictor

No Red Rose

K - Plantae

P - Magnoliopsida

C - Rosales

O - Rosaceae

F - Rosa

S - penduliina


Great Job! You saw that the Green Anole and the Boa Constrictor are in the same kingdom,

phylum, class and order. They had the most classification categories in common so they were

most closely related.


The Green Anole and the Boa Constrictor are the most closely related. They have the same

classification levels for kingdom, phylum, class and order. The rose and the green anole were

not even in the same kingdom. The alligator and the green anole were only in the same


kingdom, phylum, and class. But, since the green anole and the boa constrictor are in the same

order as well, they are more closely related.


1.21 Florida Panther and Bengal Tiger Classification

Notes:

Remember my initial challenge? I wanted to see if you could determine how closely related the Florida panther is to the Bengal tiger. Here is the full classification of each of these animals. Let’s first look at the similarities between the two. Based on the classifications shown, they both belong to the same kingdom, phylum, class, order and family. When we get down to the genus and species however, they have different classifications. So now I’d like you to explain how closely related these two organisms are in your own words.


1.22 Practice 7

Notes:

Now it’s time for you to show what you know. Type your response to the following questions in the answer box on the screen. Be sure to include information from the tutorial and answer in complete sentences. “How closely related are the Florida panther and the Bengal tiger? Could these two organisms mate and have offspring that would also be able to reproduce? Why or why not?”

If you need a little help with your response click the hint button in the lower right hand corner.

Feedback:

Thank you for your response! You should have included some or all of the following information:

The two species are from the same Kingdom, Phylum, Class, Order, and Family, which would

show a close relation.

Only Genus and Species differ.

Both are made of complex cells.

Both are vertebrate animals.

Both are mammals and give live birth.

They cannot mate and produce viable offspring.


Hint (Slide Layer)


1.23 Lesson Review

Notes:

Today I’ve shared with you that living organisms are classified by their characteristics. Many scientists, like biologists and taxonomists, classify living organisms using the Linnaean system of classification. Currently we start classification with domains, which classifies organisms based on their cell type. From that point, organisms can be classified into kingdoms all the way down to the species. The more classification levels two living organisms have in common, the more closely related they are. The order of classification from largest category to smallest category that we discussed in this tutorial are the domains, kingdom, phylum, class, order, family, genus, and species. Great work in this tutorial! Maybe one day you would like to study taxonomy like me!


1.24 Thank You

Notes:

Thank you for using this original tutorial. This screen shows your start and end times, which can be printed on your computer or tablet. Be sure to check out our other original tutorials too.

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Credits

All images licensed from Getty Images, iStock.com and/or Thinkstock.com, unless otherwise noted.

Credits (Slide Layer)

classifying living things

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