Classification of

Living Things

A. ShannonBiology I

Warm~Up

• 1. What is the scientific name for the human species?

• 2. What do you think are the common names for Felis catus & Canis familiaris?

• 3. In each case what does the first of the two names refer to?

• 4. What does the second of the two names refer to?

WE HAVE A CLASSIFICATION SYSTEM TO:

Assign a single universal name to each organism

To place organisms into groups with those that have real

biological meaning.

The Field of Biology that deals with classifying organisms is called

TAXONOMY .  Taxonomy names and groups organisms

according to their characteristics and evolutionary history.

Taxon ( taxa-plural) is a category into which related

organisms are placed A Universal System is necessary to have clear

communication among scientists worldwide.

Organisms were First Classified more than 2,000 years ago by Greek philosopher Aristotle.

 He classified organisms as either Plants or

Animals.  He grouped animals into land dwellers, water

dwellers, and air dwellers As modern science developed in the fifteenth

and sixteenth centuries, Aristotle's system was inadequate.

Carolus Linnaeus~ established a simpler system for classifying and naming organisms. He developed a Hierarchy (a ranking system) for classifying organisms that is the Basis for

Modern Taxonomy

Linnaeus used an organisms MORPHOLOGY, its form & structure, to categorize it. 

Linnaeus developed the modern system of naming known as binomial nomenclature, a two-word name (Genus~ first word & species~ second word)

Scientific names should be italicized in print or underlined when writing

Always capitalize the genus name, but write the species in lower case

The genus name may be abbreviated, but not the species

EX: Acer rubrum - RED MAPLE TREEAcer is the Latin name for Maple (genus)   rubrum is the Latin word for Red (species)   Can be abbreviated as:   A. rubrum.

EX: HUMANS ARE NAMED: Homo sapiens Homo because of our large brain and upright posture.

sapiens because of our intelligence and ability to speak.

Can be abbreviated as: H. sapiens

In Linnaeus system of classification, he ranked the categories from the broadest

and most general taxa(THE TWO KINGDOMS - PLANTS AND ANIMALS)

to the Smallest and Most Specific TAXA (INDIVIDUAL SPECIES)----------------------------------- 

• Consist of Bacteria, Archaea, & Eukarya

• Bacteria~corresponds to the Kingdom Eubacteria: unicellular& prokaryotic Some need oxygen to survive, while others are killed by it.

• Archaea~corresponds to the Kingdom Archaebacteria: unicellular & prokaryotic. Most only survive in the absence of oxygen

• Eukarya~consists of all organism that have a nucleus. Protista, Fungi, Plantae, & Animalia

• Levels are arranged in descending order..• Domain is most broad and has 3 groups (Archaea,

Bacteria, Eukarya

1. KINGDOM 2. PHYLUM 3. CLASS 4. ORDER 5. FAMILY 6. GENUS 7. SPECIES Here’s an easy way to remember those

levels!!!!! Dumb Ken Put Candy On Fred’s Good Suit

• Modern taxonomists classify organisms based on their evolutionary relationships

• Homologous structures have the same structure, but different functions & show common ancestry

• The bones in a bat's wing, human's arm, penguin's flipper are the same (homologous), but the function is different 

• Analogous structures have the same function, but different structures & do not show a close relationship (insect wing & bird's wing)

• Similarity in embryo development shows a close relationship (vertebrate embryos all have tail & gill slits)

Phylogeny (evolutionary history):• Phylogenetic trees are branching diagrams showing how

organisms are related • Also called family trees • Fossil records help establish relationships on a phylogenetic tree • Organizes living things based on their evolution (systematics) • Common ancestor is shown at the base of the tree • Most modern organisms shown at tips of branches • Each time a branch divides into a smaller branch, a new species

evolves • Cladograms shows how organisms are related based on shared,

derived characteristics such as feathers, hair, scales, etc.

When Linnaeus developed his system of classification, there were only two kingdoms, Plants and Animals. But the use of the microscope led to the discovery of new organisms and the identification of differences in cells. A two-kingdom system was no longer useful.

Today the system of classification includes six kingdoms.

The Six Kingdoms:Plants, Animals, Protists, Fungi, Archaebacteria,

Eubacteria.How are organism placed into their kingdoms?• Cell type, complex or simple• Their ability to make food• The number of cells in their body

• DOMAIN 1:Archaebacteria~ Unicellular (one celled) organisms. • Found in harsh environments (undersea volcanic vents, acidic hot

springs, salty water) • Some survive without oxygen

DOMAIN 2:Eubacteria~ Like archaebacteria, eubacteria are single celled & prokaryotic. Most bacteria are in the EUBACTERIA kingdom. They’re

found everywhere and are the ones people are most familiar with. They’re heterotrophic & autotrophic

• Eubacteria are classified in their own kingdom because their chemical makeup is different.

• Most eubacteria are helpful. Some produce vitamins and foods like yogurt. However, these eubacteria, Streptococci pictured above, can give you strep throat!

• ALL OTHER Kingdoms are in DOMAIN 3: EUKARYA

Protists• Eukaryotes • Found in kingdom Protista • Most are unicellular • Heterotrophs that ingest small food particles & digest it inside food vacuoles

containing digestive enzymes • Classified by the way they move (cilia, flagella, pseudopodia...)

These delicate looking diatoms are classified in the protist kingdom.

Fungi~ • Eukaryotic  • Important decomposers & recyclers of nutrients in the environment • Most are multicellular, but some unicellular like yeast • Nonmotile • Grow best in warm, moist environments preferring shade

Mushrooms, mold and mildew are all examples of organisms in the kingdom fungi.

Fungi are organisms that biologists once confused with plants, however, unlike plants, fungi cannot make their own food. Most obtain their food from parts of

plants that are decaying in the soil.

Plants~ All plants are multicellular & contain chlorophyll inside of chloroplasts

• Plants (also called autotrophs or producers• All plants are multicellular, eukaryotic organisms that reproduce

sexually • Many medicines are produced by plants • Plants are very diverse & may be terrestrial or aquatic• Vary in size

With over 250,000 species, the plant kingdom is the second largest kingdom. Plant species range from the tiny green

mosses to giant trees.

• Without plants, life on Earth would not exist! Plants feed almost all the heterotrophs (organisms that eat other organisms) on Earth.

Animals~ All are multicellular & eukaryotic

• Cells lack cell walls & come in a variety of shapes • Heterotrophs (take in food & internally digest it) • Have some type of skeletal support • Reproduce sexually • Show levels of organization including cell, tissue, organ, & system

Modern taxonomy uses six kingdoms --- Archaebacteria, Eubacteria, Protista, Fungi, Plantae, & Animalia

• Archaebacteria & Eubacteria are unicellular prokaryotes lacking a nucleus, while Protista, Fungi, Plantae, & Animalia are all eukaryotes with a nucleus & membrane-bound organelles 

• All members of Plantae & Animalia are multicellular organisms • Fungi & Animalia are heterotrophs, while Plantae are all autotrophs capable

of making their own food  • Archaebacteria live in harsh environments like very salty lakes; intestines of

mammals; and hot, sulfur springs & may be autotrophs or heterotrophs • Eubacteria are true bacteria some of which cause disease • Protista are mainly unicellular with a few multicellular organisms and may

be autotrophic (Euglena) or heterotrophic (Ameba) • Fungi include multicellular mushrooms, mold, unicellular yeast, etc. & are

absorptive heterotrophs (digest food & then absorb it) • Animalia are ingestive heterotrophs that take in food & then digest it inside

their multicellular bodies. • Plantae includes all plants & are the only all multicellular, autotrophic

kingdom