Classifying Living Things

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Chapter 7

• Classifying Living Things

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Classify

• To group ideas, information, or objects based on
  similarities.

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Early HistoryAristotle Greek philosopher who
developed the system of classification over 2000
years ago. The science of classifying and naming
organisms is called taxonomy. He started to
classify living things by starting with 2
kingdoms. A kingdom is the largest of the
taxonomic categories. The two kingdoms that he
started with were the plant and the animal
kingdoms.
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After he named the animal kingdom, he divided it
even more by where they lived. Animals that
lived on land and animals that lived in the water
were in two different groups. The plant kingdoms
were separated by size and structure. Even
though Aristotle made a breakthrough by
classifying living things, there were many other
scientists that criticized him.
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What was their reason?There were too many
exceptions to his rules.Frogs live on land and
water.Trees are not related just because they
are trees!!
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Scientific NamingLinnaeus a Swedish naturalist
that created a new way to classify living things.
The way that he classified these living things
were by similarities in body structure and
systems, size, shape, color, and methods of
getting food. In his system, each organism has
two names. This naming system is called binomial
nomenclature.
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The two names that each organism is given is
called its scientific name or its Latin name.
The first word is in the name is the Genus a
group of different organisms that have similar
characteristics. The second word of its name is
its specific name or species.
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The whole name gives the name of a certain
species smallest most precise classification
category.As you know, organisms of the same
species canreproduce with each
other.ExamplesCanis familiaris
dog Cyanocitta cristata Blue jayCanis
latrons Coyote Felis catus domestic
catCanis lupus Wolf Felis onca jaguar
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Modern ClassificationAristotle and Linnaeus used
characteristics of organisms that we easily
observed. Today, scientists look at other traits
to classify organisms. They look at chemical
makeup of the organism and the organisms
ancestors. They look at similarities in genes
and body structures. They also look at fossils
and the embryos of an organism as it develops.
By looking at these things, scientists can find
the phylogeny of an organism.
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Phylogeny an organisms evolutionary
histroy.Classification is based on
phylogeny!!There are six Kingdoms in modern day
classification!!
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Animal

• Eukaryotes
• Many-celled
• Move
• Members eat plants and/or other animals

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Plants

• Eukaryotes
• Many-celled
• Dont move
• Make their own food

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Fungi

• Eukaryotes
• One and many-celled
• Dont move
• Get it from other organisms

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Protista

• Eukaryotic
• One and many-celled
• Some move
• Some make their own food and some get it from
  other organisms

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Eubacteria

• Prokaryotic
• One-celled
• Some move
• Some make their own food and some get it from
  other organisms
• Examples streptococcus

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Archebacteria

• Prokaryotic
• One-celled
• Some move
• Some make their own food and some get it from
  other organisms

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Organisms, as you can see, are placed in the
kingdoms based on several characteristics. Some
of these characteristics are presence or absence
of a nucleus, single celled or multi-celled,
ability to make food, and ability to move.
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Prokaryote organisms without a
nucleusEukaryote organisms with a nucleus
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Kingdoms are also separated into smaller groups.
These smaller groups are PhylumClassOrderFamil
yGenusSpeciesEach is a division of the
division before it.
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Identifying OrganismsCommon names and scientific
namesJust because an animal or plant have the
same common name does not mean that they have the
same scientific name. Also, an organism may have
many different common names but their scientific
name is the same.
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Examples

• There are many kinds of birds that are called
  robins around the worldbut they all have
  different scientific names.
• Mountain Lion, Cougar, Puma, Florida Panther all
  are the same species!!

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Scientific names serve 4 main purposes1 Help
scientists avoid errors in communication.  2
Organisms with similar evolutionary history are
classified together.
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3 Gives descriptive information about the
species.   4 Allow information about organisms
to be organized and found easily and efficiently.
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Scientists classify living things by using more
detailed lists of traits called a dichotomous
key.Dichotomous keys are arranged in steps with
two descriptive statements at each step. The
steps are usually labeled 1a, 1b, 2a, 2b, and so
on. To use the key that is given to you, you
must always begin with a choice from the first
pair of descriptions. At the end of each step
you will either see a scientific name or
directions to go to another step with more
descriptions. You will eventually get to the
species name of the animal or plant that you are
looking for.