Classification of Living Things

Summary

This video introduces viewers to the science of taxonomy, explaining how organisms are classified and named. Starting with a quiz about a puma, cougar, or panther, the host explains that these are all names for the same animal. The video dives into the Linnaean system of classification, where organisms are categorized based on shared traits, leading to the scientific naming system known as binomial nomenclature. The video also demonstrates how dichotomous keys are used to identify species and explores how this system helps us understand relationships between different organisms.

Takeaways

• 😀 The Puma, Cougar, Mountain Lion, and Panther are all names for the same animal, depending on the region or language.
• 🧑‍🔬 Taxonomy is the scientific method used to classify and name living things, often based on observable characteristics like appearance, behavior, or location.
• 🔬 The Linnaean system of classification categorizes living organisms in a hierarchical manner, from broad categories to more specific ones.
• 📜 Binomial nomenclature is the system of naming organisms using two terms: the genus and species, such as Homo sapiens for humans.
• ✍️ In binomial nomenclature, the genus name is capitalized, the species name is lowercase, and both are italicized (or underlined when handwritten).
• 🌍 Humans belong to the domain Eukarya, kingdom Animalia, and have a hierarchical classification that descends to Homo sapiens.
• 🐻 Organisms that share the same genus are more closely related, such as grizzly bears and polar bears, which are more closely related than a panda bear.
• 🧩 Dichotomous keys are tools that help identify organisms based on a series of choices about their observable characteristics.
• 📚 Dichotomous keys can be presented in both text and pictorial forms, guiding users step-by-step to identify an organism.
• 🔑 Dichotomous keys allow for identification of even closely related species by focusing on distinguishing traits.

Q & A

What animal is referred to by multiple names such as Puma, Cougar, Mountain Lion, and Panther?

The animal referred to by these names is the same, and depending on the region or dialect, it has over 80 different names.

What field of science focuses on classifying and categorizing living organisms?

The field of science that focuses on classifying and categorizing living organisms is called taxonomy.

What are some of the characteristics used to classify organisms in taxonomy?

Taxonomists use observable characteristics such as morphology (physical appearance), behavior, and geographic location to classify organisms.

Why can it be difficult to distinguish between species, particularly in certain environments like Lake Malawi?

In environments like Lake Malawi, which has over 1,000 species of fish, distinguishing between species can be challenging due to the high number of closely related species and their similarities.

What is binomial nomenclature, and how is it structured?

Binomial nomenclature is a system of naming organisms using two names: the genus and the species. The genus is always capitalized, while the species is not, and both are italicized or underlined when handwritten.

Who introduced the system of classification we commonly use in biology, and what is it called?

The system of classification was introduced by Swedish naturalist Carl Linnaeus, and it is called the Linnaean system of classification.

How is the Linnaean system of classification structured?

The Linnaean system is hierarchical, with levels of classification called taxa. It starts with the broadest category (domain) and narrows down to the most specific (species), with organisms becoming more closely related at each level.

What are the genus and species names for humans?

The genus and species names for humans are 'Homo sapiens.'

How can taxonomy help us determine how closely related different organisms are?

Taxonomy helps determine how closely related organisms are by comparing how many levels of the hierarchical system (such as family or genus) they share. The more levels they share, the more closely related they are.

What are dichotomous keys, and how do they work?

Dichotomous keys are tools used to identify organisms by following a series of choices based on observable characteristics. These choices lead the user to the correct identification of the organism.

Outlines

00:00

🦁 Exploring the Many Names of One Animal

The video starts with a quiz asking viewers to identify an animal that can be called a puma, cougar, mountain lion, or panther, emphasizing how regional and linguistic differences result in this one species having over 80 names. This serves as an introduction to the need for a universal classification system in biology, known as taxonomy, which helps scientists categorize and name living organisms systematically based on observable traits like morphology, behavior, and geography.

05:00

🔬 Introduction to the Linnaean System of Classification

The Linnaean system, created by Carl Linnaeus, is introduced as the standard method of biological classification. It organizes living organisms into hierarchical levels, or taxa, starting from broader categories to more specific ones. At the bottom of this hierarchy are the genus and species, which together form the binomial nomenclature or scientific name for each organism. For example, humans are classified as *Homo sapiens*, with 'Homo' being the genus and 'sapiens' the species. Rules for writing scientific names, such as capitalization and italicization, are also explained.

10:02

📊 Understanding Hierarchical Classification Using Humans

A deeper dive into the hierarchical classification system is provided, using humans as an example. The system starts from the domain, which is the largest and most inclusive taxon, and moves down through kingdom, phylum, class, order, family, genus, and species. Humans belong to the domain Eukarya, kingdom Animalia, phylum Chordata, and class Mammalia. The breakdown helps explain how living things are grouped based on shared characteristics, with humans being the only living species in the genus *Homo*.

🐼 Comparing Relatedness: Bears and Pandas

This section explores how the hierarchical system of classification can reveal how closely related different species are. Through examples like the panda bear, polar bear, grizzly bear, and red panda, it is shown that while all three bears share the same family, the polar and grizzly bears are more closely related because they share the same genus. The red panda, despite its name, is more closely related to raccoons than pandas.

🔍 Using Dichotomous Keys for Species Identification

Dichotomous keys, both pictorial and textual, are introduced as tools for identifying organisms based on a series of criteria. These keys operate like a 'choose your own adventure' story, where you follow pathways based on observable traits, such as whether an organism has wings or a shell. The process is demonstrated using examples, where a bat and a turtle are identified by following the appropriate steps in the key.

🗝️ Mastering Dichotomous Keys: Practical Example

A more detailed look at using dichotomous keys continues with an example organism that does not have wings but does have a shell, ultimately identified as a turbot. The section reinforces that while the examples are simple, the method remains the same for more closely related organisms, making dichotomous keys a valuable tool in species identification.

🔬 Conclusion: Applying Taxonomy and Dichotomous Keys

The video concludes by summarizing the importance of taxonomy in categorizing and classifying living things. It reinforces the understanding of hierarchical classification, the use of binomial nomenclature, and how dichotomous keys can help identify organisms in the field. These tools not only distinguish individual species but also help show how closely or distantly related different organisms are.

Keywords

💡Taxonomy

Taxonomy is the scientific field that focuses on classifying, categorizing, and naming living organisms. It plays a crucial role in the video's theme by providing a structured way to identify and differentiate species, as illustrated by the example of the animal with over 80 names (puma, cougar, etc.). Taxonomy ensures that scientists have a universal system for referencing organisms, regardless of language or region.

💡Binomial nomenclature

Binomial nomenclature is a two-part naming system used in taxonomy to classify living organisms, consisting of the genus and species names. The video explains how this system, popularized by Carl Linnaeus, is essential for scientific identification. For example, humans are classified as 'Homo sapiens,' with 'Homo' as the genus and 'sapiens' as the species. This system helps scientists universally name and differentiate organisms.

💡Linnaean system

The Linnaean system is a hierarchical classification method developed by Carl Linnaeus, which organizes living things into groups or 'taxa' based on shared characteristics. The video describes this system as foundational in biology, highlighting how it categorizes organisms from the broadest grouping (domain) down to the most specific (species). The example of humans moving through various taxa, from domain Eukarya to species Homo sapiens, illustrates its use.

💡Genus and species

Genus and species are the two lowest taxa in the Linnaean classification system, used together in binomial nomenclature to identify organisms. The genus name is capitalized, while the species name is not. For instance, humans are identified as 'Homo sapiens.' This concept is central to the video as it shows how organisms are given scientific names that are recognized globally.

💡Eukarya

Eukarya is the domain that includes organisms with eukaryotic cells, meaning they have a true nucleus. This is one of the largest and most diverse groups in the hierarchical classification system. The video uses humans as an example, explaining that they belong to this domain because their cells contain nuclei. Eukarya contrasts with other domains like Archaea and Bacteria, which do not have true nuclei.

💡Dichotomous key

A dichotomous key is a tool used to identify organisms by answering a series of questions that lead the user through a decision tree based on observable characteristics. The video shows both pictorial and text-based dichotomous keys, illustrating how they are used to classify organisms in the field by narrowing down options based on visible traits, like whether the organism has wings or a shell.

💡Morphology

Morphology refers to the study of the form and structure of organisms. In the video, morphology is highlighted as one of the observable characteristics used in taxonomy to classify organisms. The example of distinguishing fish species in Lake Malawi based on physical traits showcases how morphology helps scientists categorize closely related species.

💡Phylum Chordata

Phylum Chordata includes animals that have, at some point in their life cycle, a notochord, a hollow dorsal nerve cord, and other characteristics. Humans, as well as other vertebrates, are placed in this phylum. The video uses humans as an example, showing how they belong to this phylum due to their anatomical features, as part of the larger classification system.

💡Closely related species

Closely related species are organisms that share more taxa as they move down the Linnaean hierarchy, making them more genetically and evolutionarily similar. The video explains this concept with the example of polar bears and grizzly bears, which share the same genus and are more closely related than a panda bear, which only shares the same family with them.

💡Domain

Domain is the highest and broadest taxonomic rank in the Linnaean system, encompassing the largest groupings of organisms. The video describes three domains—Eukarya, Archaea, and Bacteria—using humans as an example to explain that they belong to the domain Eukarya due to their eukaryotic cells. This concept is central to understanding how living organisms are grouped at the highest level.

Highlights

This animal has over 80 different names depending on the region, dialect, or language.

The field of taxonomy is used to classify, categorize, and name living organisms using scientific methods.

Taxonomy often categorizes organisms based on observable characteristics like morphology, behavior, or geography.

The Linnaean system of classification is commonly used in introductory biology to categorize living organisms.

The Linnaean system uses a hierarchical method, starting with broad categories and narrowing down to individual organisms.

The system of naming organisms is called binomial nomenclature, which uses two names: genus and species.

Humans are classified as Homo sapiens using the Linnaean system, where 'Homo' is the genus and 'sapiens' is the species.

When writing scientific names, the genus is capitalized and the species is lowercase, and the names are italicized.

Humans belong to the domain Eukarya, which includes all organisms with cells that have a nucleus.

The system of classification helps determine how closely related organisms are, such as comparing bears and pandas.

Dichotomous keys are tools used to help identify organisms by following a series of choices based on observable traits.

Pictorial and text-based dichotomous keys are examples of how to identify organisms using taxonomy.

Using a dichotomous key, you can systematically narrow down an organism’s identity by answering yes or no questions about its features.

The red panda is more closely related to a raccoon than to the panda bear, despite similarities in diet and behavior.

Dichotomous keys are a practical way to identify organisms in the field, based on easily observable criteria.

Transcripts

so I'm gonna start off this video here

with a little quiz this animal here is a

a Puma be a cougar see a mountain lion

or D a panther which one did you pick

well if you said any of those you're

right because this animal right here

depending on region that you live in or

depending on the dialect that you speak

or even the language that you speak has

over 80 different names so if you are a

biologist and you are speaking about

this particular animal in one part of

the country to an individual another

part of a country or maybe even a to an

individual who speaks a different

language

how are we to agree upon what to call

this organism surely there's got to be a

better way that we have to classify in

named things using some scientific

method so yes

scientists have a field of study that we

refer to as taxonomy and taxonomy

identifies and categorizes and

classifies living things and a lot of

times this is just based on the

observable characteristics so it could

be things like morphology or what that

particular organism looks like it could

be behavioral how they behave and how

they interact under certain conditions

it could be geographic where these

organisms are located relative to one

another but even then it's not quite

that simple sure it might be easy to

identify an elephant versus a crayfish

but if we take a look at something like

fish it's not that easy to distinguish

between individuals of different species

for example we can take a look at one

lake in Africa like Malawi and that lake

itself has over a thousand different

species of fish and while we are in an

era where DNA is at least a little

better understood than it has been in

decades past

it's not always easy especially in the

field to try and take a DNA sample and

compare it to something else so the

system that I'm gonna introduce you to

in the system that we're gonna focus on

in this video in fact the system that's

most often focused on an introductory

biology courses is the Linnaean system

of classification so carolus linnaeus or

carl linnaeus if you want to anglicize

his name was a Swedish naturalist and he

came up with a way of categorizing

living things based on their shared

characteristics and so he categorized

these living things

two different layers or taxa as they are

called the top or highest level of this

hierarchical method of classification

was the one in which we found the most

organisms but they were the most

distantly related as we progress down

through the different levels of the

hierarchy through the different taxa

these organisms became more and more

closely related until at the very bottom

we had individual organisms and so in

order to identify one organism from

another we take the final two or the

bottom two levels of these taxa and we

put them together into two names and

because we're using two names and we're

naming something we refer to this as

binomial nomenclature and it's probably

something you're fairly familiar with

the two taxa that we use are the genus

and the species and we put these

together and we have the genus in the

species name or as we say it the

scientific name for a particular

organism so for example humans genus is

Hummel and the species refers to sapiens

so Homo sapiens or Homo sapiens are the

scientific name at least based on the

Linnaean system of human beings now I

want you to notice a couple of things we

put together the scientific name when

we're using binomial nomenclature the

genus name is always capitalized while

the species name is not capitalized and

you will notice especially when we can

that it's going to be italicized if you

were to handwrite the genus and species

name because you are using the

scientific name for an organism through

binomial nomenclature you would

underline it because it's not easy to

italicize things when you're writing it

so this system this Linnaean system of

classification using binomial

nomenclature the genus in the species

name is currently the accepted method

for identifying these organisms using

some type of classification system and

taxonomical study now let's delve into

this hierarchical system of

classification a little bit deeper using

humans as an example so in the domain

this is the largest grouping of

organisms that we have in this layer of

taxa in this hierarchical classification

system and the domain that

humans are in is something called

Eukarya and eukaryote dystrophy

organisms that are eukaryotic that have

a true nucleus so anything that has a

cell with a nucleus is going to be found

in this domain it's extremely large and

extremely diverse we have closely

related relatives and we have extremely

distantly related relatives now as we

move down one level or one taxon into

the kingdom we see that we are in

kingdom Animalia we are an animal we

have a backbone we have a notochord so

we are in the phylum Chordata we are in

the class Mammalia and in the order

primates so we are in the family a

minute.i otherwise known as the great

apes or the hominids

this is the last taxa that we have where

we have a living relative so as we move

into the genus Homo we are the only

organisms in that particular genus left

living on this planet and therefore

being individual species were obviously

the only sapiens or sapiens that are

found on this planet as well it should

be noted that there are some other

divisions subdivisions infra divisions

super divisions within this particular

type of naming system but we're only

going to focus on these major eight for

the time being so not only does this

hierarchical system of classification

help us classify and categorize living

things but it can also help us determine

how closely related certain organisms

are so here I have some imagery I have a

panda bear I've got a red panda I've got

a polar bear and I've got a grizzly bear

so just take a second look at these

images and what I want you to think

about is how closely related do you

think the panda bear is to each one of

these other organisms well here I want

to show you the genus and species name

for each of them now notice that the

panda bear is not in the same genus as

any one of these organisms so it's

actually not as closely related to the

polar bear as say the grizzly bear is

and in fact it's not really all that

related to the red panda either sure

they both eat a lot of

boo and they both have developed sort of

thumbs in order to grasp onto this

bamboo but they're actually quite

distantly related the red panda is a

little bit more related to a raccoon

than it actually is to the panda bear

and the panda bear is believed to be

somewhat closely related to the polar

bear but the polar bear in the grizzly

bear

as we can see share the same genus and

so they are more closely related because

they are more closely related in terms

of the level of the taxa that they have

in common but if we move up a level we

will see that all three bears do share

the same family so they are all related

in the sense that they belong to the

same family but the grizzly bear and the

polar bear are more closely related

because they share the same genus okay

great so we've got a system of

classifying and categorizing living

things but how does that help us in

practice meaning is there a way that

this system can be used to help identify

an organism out in the field well yeah

we do have a couple of tools that we can

use to help us identify these organisms

or at least to narrow down the field of

what a potential organism could be so

here we have a couple of tools these are

referred to as dichotomous keys one of

them is a pictorial representation where

we're kind of following the line and the

other one is a text representation where

we are reading through certain criteria

I mean you may be familiar with books

that we refer to as

choose-your-own-adventure at least they

were to choose your own adventure when I

was reading them as a kid I don't know

what they're called now but the book

kind of work like this you read through

a page and if you decided to go into the

scary dungeon you would go to page 87

and if you ran away in fear you would go

to page 33 and invariably if you ran

away and fear something horrible would

happen to you and if you went into the

dungeon then the story would continue on

but they're kind of like that you have

to identify what the criteria are before

you can move on to the next step so what

we're going to do is we're going to go

through each of these dichotomous keys

to see if we can figure out what a

particular organism is or how we would

go about using these to identify what a

particular organism

now we're gonna be fairly high level

here but remember that it is just an

introductory exercise so let's take a

look first of this pictorial

representation you will notice that

basically there's multiple pathways to

follow and it's just based on whether or

not a certain criteria is met now for

the most part these are going to be

easily observable criteria it's not

going to be something like how many

chambers of the heart does this organism

have because that's not something that

we can easily identify from its outward

appearance so if we take a look at our

first option does this organism have

wings yes or no so if we're going to use

a bat as an example we are going to say

that yes it has wings so we are gonna

move to this branch of it does this

organism possess feathers well the

answer is no the bat does not possess

feathers so we would follow this branch

now since we only have four options here

and all other options are eliminated

therefore it can only be a bat in this

scenario okay so now we're gonna move

over to the text version of the

dichotomous key now even though the

organisms that we are looking at here

are fairly distinguishable from one

organism to the next remember we're just

learning how to use this dichotomous key

right now so the first question is does

this organism have wings and I think

it's fairly evident that if this is our

example organism it does not and so we

are going to move down to question

number three question number three now

States does this organism have a shell

well yes this organism has a shell so in

that case this organism is a turbot so

here we have used that I kata miss Kibo

in pictorial form and in text form to

help us distinguish between different

organisms and ultimately to help us

identify what a particular organism is

now it should be noted that these again

are fairly straightforward examples but

the way that these dichotomous keys

function then the way that you use the

dichotomous keys are the same now you

are probably going to be using them to

distinguish between far more closely

related organisms but the mechanism by

which you use these is going to be the

same so hopefully after watching this

video you have a better understanding of

taxonomy and how we use that field of

study to categorize and classify living

things you understand the different

levels or taxa in terms of hierarchical

classification and now

only how we use genus and species to

identify what those individual organisms

are but also how we can use the

different layers to identify how closely

related or how distantly related to

species are in addition hopefully now

you understand a little bit better or at

least have been introduced to how to use

dichotomous keys to help us identify and

narrow down what a particular organism

may be thanks for watching