Classification of living things
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Classification of Living Things. Classification of Living Things. Taxonomy : Branch of biology that names organisms according to their characteristics. Putting things into orderly groups based on similar characteristics. Why do scientists classify?

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Classification of living things1
Classification of Living Things

  • Taxonomy: Branch of biology that names organisms according to their characteristics.

  • Putting things into orderly groups based on similar characteristics.

  • Why do scientists classify?

    • Biologists classify living organisms to answer questions such as:

      • How many known species are there?

      • What are the defining characteristics of each species?

      • What are the relationships between these species?


(300 B.C.)

  • Aristotle

    • Greek philosopher and teacher more than 2000 years ago

    • The first person to group or classify organisms




Based on size of stem

Based on where they lived

Limitations of early classification
Limitations of Early Classification

1. Not all organisms fit into Aristotle’s 2 groups (plants or animals)

Ex: Bacteria Fungi

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Limitations of early classification1
Limitations of Early Classification

Ex: A jelly fish isn’t a fish,

but a seahorse is!

2. Common names can be misleading

Sea cucumber sounds like a plant but… it’s an animal!

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Limitations of early classification2
Limitations of Early Classification

3. Common names vary from place to place

Ex: puma, catamount, mountain lion, cougar are all names for same animal

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Limitations of early classification3
Limitations of Early Classification

4. Same organisms have different names in different countries.


Streifenhornchen (German)

Tamia (Italian)

Ardilla listada (Spanish)

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Limitations of early classification4
Limitations of Early Classification

  • Early Solution:

    • Description of Organism Using Latin Names


Quercus foliis obtuse-sinuatis setaceo-mucronatis

“oak with leaves with deep blunt lobes bearing hairlike bristles”

Limitations of early classification5
Limitations of Early Classification

  • Problem with Latin Name descriptions?

  • Names too long and difficult to remember

  • Names don’t illustrate evolutionary relationships

Carolus linneaus
Carolus Linneaus

Devised a new classification system based on morphology

(Organism’s form and structure)


“Father” of taxonomy and binomial nomenclature

Carolus linnaeus
Carolus Linnaeus

  • Linnaeus’s Classification System

    • Organisms grouped in a hierarchy of seven different levels

    • Each organism has a two part scientific name

      • Binomial Nomenclature

  • Kingdom

    • Phylum

      • Class

        • Order

          • Family

          • Genus

          • Species








  • Kingdom

    • Phylum

    • Class

    • Order

      • Family

      • Genus Species








Binomial nomenclature
Binomial Nomenclature

  • Binomial Nomenclature: Two name naming system

    • Italicized or Underlined

  • 1st Name = Genus

    • Capitalized

  • 2nd Name = Species Identifier

    • Lower case

Binomial nomenclature1
Binomial Nomenclature

Vampire batDesmodus rotundus

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Eastern chipmunk


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Binomial nomenclature2
Binomial Nomenclature


Homo sapiens


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Modern taxonomy
Modern Taxonomy

Modern taxonomy involves the use of Linnaeus’s naming/classification system, but with additional kingdoms.

Modern taxonomy1
Modern Taxonomy

  • Organizes living things in the context of evolution

Modern taxonomy2
Modern Taxonomy

  • Scientists use a variety of information in order to classify organisms:

    • Fossil Record

    • Morphology

    • Embryology

    • Chromosomes

    • Macromolecules (DNA and Proteins)

1 fossil record

We can trace some changes over time through the fossil record.

Evolutionary history =


2 morphology

Shape and Function

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  • Homologous Characteristics:

    • Same embryological origin (may have similar structure and function)

    • Example: Bat Wing and Human Arm

      Homologous characteristics suggest a

      recent common ancestor


Bat wing

and human arm

develop from same embryonic structures




  • Analogous Characteristics:

    • May have similar structure and function, but different embryological origin

    • Example: Bird Wing and Butterfly Wing

      Analogous characteristics evolved separately.

      Organisms not necessarily closely related.


Bird wing and

butterfly wing

have evolved with similar function


different structure


Insects and birds NOT closely related!

I don t get it
I don’t get it!

  • Analogous characters the same function but different underlying construction.

  • Homologous characters different functions, but show an anatomical similarity inherited from a common ancestor. **Important for cladograms!**

3 embryology
3. Embryology

Animals whose embryos develop in a similar pattern may be related

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Even differences show relatedness

amnion /am·ni·on/ (am´ne-on) bag of waters; the extraembryonic membrane of birds, reptiles, and mammals, which lines the chorion and contains the fetus and the amniotic fluid

4 chromosomes
4. Chromosomes

Similar karyotypes suggest closer relationships.


Chimpanzee: Middle School Life Science , published by Kendall/Hunt.

Human- 46 chromosomes Chimpanzee- 48 chromosomes

Even differences show relatedness

Chimpanzees have 2 smaller chromosome pairs we don’t have

Humans have 1 larger chromosome pair (#2) they don’t have.


Chimpanzee: Middle School Life Science , published by Kendall/Hunt.

5 macromolecules
5. Macromolecules

Comparison of macromolecules such as Proteins and DNA

Organisms with similar sequences are (thought to be) more closely related.

Evolutionary relationships
Evolutionary Relationships

  • Determined through the use of:

    • Morphology

    • Fossil Record

    • Embryology

    • Chromosomes

    • Macromolecules

      Evolutionary relationships can be illustrated on a phylogenetic tree



Evolutionary History

Shows evolutionary relationships based on “shared derived characteristics”

Cladistic relationships illustrated through the use of a Cladogram


  • The greater the number of derived characters shared by groups, the more recently the groups share a common ancestor.










  • Domains are taxonomic groups that are even bigger than kingdoms. Each of the six kingdoms belongs to a single domain.

  • Three Domains:

    • 1. Archaea

    • 2. Bacteria

    • 3. Eukarya

Domain Bacteria

  • Eubacteria are prokaryotes whose cell walls contain peptidoglycan.

  • “True bacteria”

Domain Archaea

  • Archaea are thought to be more ancient than bacteria and yet more closely related to our eukaryote ancestors.

  • Cell walls without

  • peptidoglycan

  • They are called extremophiles because they can live in extreme environments.

Domain Eukarya

  • All eukaryotes are classified in Domain Eukarya.

  • Domain Eukarya contains Kingdom Protista, Kingdom Fungi, Kingdom Plantae, and Kingdom Animalia.

Kingdom archaebacteria
Kingdom Archaebacteria

Some archaebacteria are heterotrophs, but some are autotrophs.

Most archaebacteria are unable to move, but a few can move.

Archaebacteria are the old known life forms.

Why are archaebacteria not classified with “modern bacteria”?

Archaebacteria and eubacteria are chemically different!

Kingdom archaebacteria1
Kingdom Archaebacteria

Cool archaebacteria info:

Three divisions of archaebacteria:Methanogens: methane producing organisms

Thermophiles: These can live in extremely hot, acidic environments like sulfur springs.

Halophiles: Can only live in bodies of concentrated salt water, like the Dead Sea.

Kingdom eubacteria
Kingdom Eubacteria

Traditional prokaryotic bacteria


Some are autotrophic, some are heterotrophic.

Found in soil, water, human body, etc.

Esterichia coli (E. coli) is found in large numbers in human intestines, where it produces vitamin K.

Kingdom eubacteria1
Kingdom Eubacteria

Unlike archaebacteria, eubacteria require oxygen.

Some bacteria contain cilia or flagella which allows them to move.

Kingdom protista
Kingdom Protista

  • Eukaryotic organisms.

    • This is why they are not considered bacteria!

  • Most protists are single-celled but some are simple, multicellular organisms

  • “Junk Drawer Kingdom” or “Odds and Ends Kingdom”

  • Some protists are autotrophic, some protists are heterotrophic.

    • Animal-like protists, plant-like protists

Kingdom protista1
Kingdom Protista

Most protists are able to move, but some cannot

Kingdom fungi
Kingdom Fungi

Molds and mushrooms are examples of fungi.

Fungal cell walls contain chitin.

(cell walls of plants contain cellulose).

The study of fungi is known as mycology.

Fungi are more closely related to animals than to plants!

Usually, the only fungi that we see are reproductive structures. Tasty!!

Kingdom plantae
Kingdom Plantae

Plants are eukaryotic, multicellular organisms.

They are autotrophs- they make their food through photosynthesis.

Plants can be found on land and in shallow water (where there is light)

Kingdom plantae1
Kingdom Plantae

Plant cells have cell walls

Made up of cellulose, to provide them with a rigid structure

Some plants reproduce through both asexual and sexual reproduction.

Kingdom animalia
Kingdom Animalia

This kingdom contains many complex, multicellular organisms.

All animals are heterotrophic.

All animals are able to move, even if it is only during some stages of the life cycle.

Kingdom animalia1
Kingdom animalia

All animals are eukaryotic organisms, but animal cells do not have a cell wall.

Most animals reproduce through sexual reproduction, but some are able to reproduce asexually (or both!).

The most simple organism

in the kingdom animalia

is a sponge.

A dichotomous key is a classification key that gives the students two choices to choose from before moving on to the next set of choices. 

Dichotomous key activity
Dichotomous Key activity students two choices to choose from before moving on to the next set of choices. 

With the person at your table, create a dichotomous key for the shoes at the front of the room. Remember, this should be a series of two choices that each lead you to next series or to the correct shoe. You can use descriptions in your choices, such as, casual or dress shoe.

1 a. Men’s ----------go to 2 students two choices to choose from before moving on to the next set of choices. 1b. Women’s ------go to 32 a. Casual ----------Converse2 b. Dress ------------ Merrell3 a. Casual -----------go to 43 b. Dress ------------go to 74 a. Open toe -------go to 54 b. Closed toe -----go to 65 a. Brown ------------Route 66 flip-flop5 b. Black --------------Yellowbox flip-flop6 a. Brown ------------Merrell6 b. Blue ----------------Reef7 a. Open toe---------go to 87 b. Closed toe-------go to 98 a. Purple ------------Mossimo8 b. Silver -------------Kelly & Katie9 a. Pointy toe ------ DL9 b. Round toe------Madden Girl

If the bobcat and lion are in the same order they are also in the same
If the Bobcat and Lion are in the same Order, they are also in the same _______________.

Class, Phylum, & Kingdom

Which two are analogous? example of?

Which two or homologous?

Fill in the cladogram with the following organisms: example of?Pigeon, Hagfish, Chimpanzee, Lizard, Perch, Mouse, Salamander

Write the Western Diamondback Rattlesnake’s scientific name in the correct format for binomial nomenclature.


crotalus atrox