Classification of Living Things
Summary
TLDRThis 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
🦁 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.
🔬 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.
📊 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.
Mindmap
Keywords
💡Taxonomy
💡Binomial nomenclature
💡Linnaean system
💡Genus and species
💡Eukarya
💡Dichotomous key
💡Morphology
💡Phylum Chordata
💡Closely related species
💡Domain
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
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