Classification

Chapter 18

Taxonomy

• Science of classifying organisms.

Why classify?

• Over 10 million species on Earth

The problem with common names…

Mountain lion, puma, cougar or a panther.

Pill bug, doodle bug, roly poly

Common names vary among languages and even among regions, sometimes different species even can share the same common name.

• Without using the name of the organism use as many terms as needed to describe the organism and it’s differences from other organisms.

Early efforts to classify

• Described physical characteristics, sometimes over 20 words long for one name.

• PROBLEM : different scientists describe organisms differently

Binomial Nomenclature

• Set up by Carolus Linneaus – father of taxonomy, used physical characteristics to classify

• Each species is given a 2 part name, the first word is capitalized and the second is lowercase, both are written in italics or underlined.

Ex. Homo sapien Homo sapien

Say my name, say my name.

Scientific Names• For a grizzly bear, Ursus is the genus name

and arctos is the species name• Species names are unique to that individual group

of organisms and are usually a description of an important trait or an indication of where that organism lives

• Ursus maritimus, where does he live?– Maritim means to live near the sea

Common Name: Grizzly Bear Scientific Name: Ursus arctos

Common Name: Polar Bear Scientific Name: Ursus maritimus

Felis domesticus, catwhat does “domesticus” mean?

Meow.

Roar (loudly).

Domesticus = “of the house”

Scientific NamesAll bears are NOT alike- but they are

all bears.Scientific Names of bears:

Common Name: Grizzly Bear Scientific Name: Ursidae Ursus arctos

Common Name: Polar Bear Scientific Name: Ursidae Ursus maritimus

Common Name: Black BearScientific Name: Ursidae Ursus americanus

Common Name: Panda Bear Scientific Name: Ursidae Ailuropoda melanoleuca

Common Name: Sloth BearScientific Name: Ursidae Melursus ursinus

KingPhillipCameOver For Good

Spagetti.Yummy.

Linnaeus’s System of Classification• Linnaeus’s system is hierarchical, and includes

7 levels (largest to smallest), each level is called a taxon or taxa(plural).

Kingdom

Phylum

Class

Order

Family

Genus

Largest- plants, animals, insects, fish, bacteria- everything fits in here

SpeciesSmallest

Homo

sapiens

Animalia

Chordata

Mammalia

Primates

Hominidae

Example: Humans

Grizzly bear Black bear

Giant pand

a

Red fox Squirrel

Coral

snake

Sea star

KINGDOM Animalia

PHYLUM Chordata

CLASS Mammalia

ORDER Carnivora

FAMILY Ursidae

GENUS Ursus

SPECIES Ursus arctos

Bear Classification as an Example

Question:Which organism is

more closely related to the polar bear, the squirrel

or the fox?

Duh, it’s the fox.

Organisms are increasingly similar as you go from the level of kingdom to the level of species.• Kingdom Animalia, Phylum Chordata,

Class Mammalia, Order Carnivora

Family Canidae (canine)

Genus Canis

Are these dogs the same species?

YES!

• Remember the definition for species? Group of similar organisms that can breed and produce fertile offspring.

horse + donkey = mule (non-fertile offspring)

species + species = non-species

• All dogs are given the species name Canis familiaris, the differences seen are called breeds.

Similarities in DNA and RNA

• Most classification methods are based on physical similarities and differences.

• However the genes of many organisms show important similarities at the molecular level.

• These similarities can help classify organisms and figure out their evolutionary relationships.

Similarities in DNA and RNA• Most classification methods are based on physical similarities and

differences.• genes of many organisms show important similarities at the

molecular level.• These similarities can help classify organisms and figure out their

evolutionary relationships.

African Vulture

American vultureStorks

Falcon

Molecular Clocks• DNA comparisons can also be used to mark the

passage of evolutionary time• Molecular Clock model uses DNA comparisons to

estimate the length of time that 2 species have been evolving independently– Looks for mutations that separate 2 species– Other changes in DNA – Compares DNA sequences between species

Human:   CCA TAG CAC CTA Pig:   CCA TGG AAA CGAChimpanzee:   CCA TAA CAC CTA Cricket:   CCT AAA GGG ACG

Which organisms are more closely related?

Why?

Only 1 mutation separates human and chimp in this portion of the gene

Evolutionary Classification

Crab Barnacle

Limpet

CLADOGRAM

Crustaceans

Gastropods

Molted exoskeleton

Tiny free-swimming larva

Actually, crabs and barnacles are more closely related evolutionarily.

This branching shows that crabs and barnacles share a more recent common ancestor.

Derived characteristics in crustaceans = -Segmented bodies-Hard external skeleton shed during growth

Barnacles

Limpet

Crab

Box 13

Cladogram = shows the evolutionary relationships among a group of organisms

Box 14

Classification today

• Developed by Whittaker, contains the 5 kingdoms

• Greatest division is no longer between plants and animals but rather prokaryotes and eukaryotes

• The three “higher” kingdoms are distinguished by their ecological strategies:absorption (FUNGI), consumption (ANIMALIA) and production (PLANTS)

Kingdoms and Domains• In Linnaeus’s time, life was much

simpler. Either you were a plant or an animal.

• Today, classification is more complicated. – Protists? Bacteria? Viruses?

• Tree of Life (www.tolweb.org)• Life is full of Diversity

– Robert Hooke and Van Leewenhoek – showed us the microscopic world, bacteria, protists, microorganisms

– Discovering all these microscopic life forms, added branchesbranches to the Tree of Life

Sec. 18-3

Tre

e o

f Life

The Five Kingdoms

• Kingdom Monera• Kingdom Protista• Kingdom Fungi• Kingdom Plantae • Kingdom Animalia** Some scientists argue that there are 6

kingdoms, they divide Kingdom Monera (bacteria) into 2 separate kingdoms known as Kingdom Archaebacteria and Kingdom Eubacteria.

Then what on Earth is a Domain?• A new taxonomic category that is

larger than a kingdom.• 3 total

1. Domain Eukarya – protists, fungi,plants and animals

2. Domain Archaebacteria3. Domain Eubacteria

Domain Bacteria

• Unicellular• Prokaryotic• Cell walls are rigid and thick• Corresponds with the kingdom

eubacteria• Autotrophs and heterotrophs

Domain Archaea• Unicellular• Prokaryotic• Live in extreme environments such as sulfur

springs, salt lakes• Most are anaerobic• Cell walls lack peptidoglycan, cell membranes

contain unusual lipids not found in any other organisms

• Corresponds with the kingdom archaebacteria• Examples include methanogens, bacteria that get

their energy from methane gas1. Methanogens (methane-producers)--

responsible for swamp gas and…2. Extreme Thermophiles--live in hot springs

and black smokers. 3. Extreme Halophiles--live in saturated brine and salt crust.

Owen’s Lake, NV

YellowspringsYellowstone Park

Domain Eukarya

• Eukaryotic• Uni and multicellular• Auto or heterotrophs• Some are photosynthetic (plants)• Contains 4 kingdoms, plantae,

animalia, fungi and protista

Kingdom Monera Includes all types of bacteria – archaic and true

Bacteria on a contact

lens

Some microbes live on our skin and protect us from many harmful agents. The drier areas, like the back, have few microbes; moist areas, such as under the arm, have many more.

Escherichia coli (a.k.a. E. coli) lives in the gut, where it helps digest food

Staphylococcus (a.k.a. staph) can cause serious infections and is one of the most drug-resistant bacteriaLactobacillus bulgaricus helps turn milk into cheese, yogurt, and other dairy products. Lactose intolerant anyone?

Kingdom Protista

• 200,000 species• Any organism that is not a plant, animal,

fungus or prokaryote• Eukaryotes• Most are unicellular but there are some

multicellular• Animal-like protists are considered

heterotrophs• Plant-like protists are considered

autotrophs• Algae, euglena, paramecium, ameoba,

slime molds

Examples of Protists

Kingdom Fungi

• Mushrooms, molds, yeast• Many grow from ground• Eukaryotic heterotrophs that have cell

walls made of chitin, also found in the tough outer covering of insects.

• Many feed off of decaying soil, some are parasites, secrete enzymes that digest and then absorb (not eat) the smaller food molecules

• Some produce sexually, some asexually

Examples of Fungi

Kingdom Plantae

• Photosynthetic, autotrophic, eukaryotes

• Cell walls made of cellulose• Nonmotile

Kingdom Animalia

• Heterotrophic, multicellular, eurkayotes

• No cell walls• Sponges, worms, fish, insects,

mammals

Animalia

• The Kingdom Animalia is divided into 6 phyla:

1. Sponges and Cnidarians2. Mollusks3. Worms4. Arthropods5. Echinoderms6. Verterbrates

1. Sponges and Cnidarians

- The only animals that do not have tissues.- Mostly marine.- Ex. Jellyfish, corals

2. Mollusks

• Have something called a coulomb (sac-like structure) that encloses their internal organs.

• Most have a hard external skeleton (shell).

• Ex. Snails, oysters, clams, octopuses

2. Mollusks

3. Worms

• Cylinder shaped bodies.• Live on both land and water.

4. Arthropods

• Most diverse of all animals.• Have an external skeleton.• Have jointed appendages, such as

antennae and jaws. • High rate of reproduction.• 2/3 of all animals.

4. Arthropods

5. Echinoderms

• Ability to regenerate a lost limb.• Ex. Sea stars, sea urchins

6. Verterbrates

• Internal skeleton made of bone.• Includes mammals, fish, birds,

reptiles and amphibians.

Warm Up #1 on a blank sheet of paper

1. What is taxonomy?2. What scientist developed the

classification system we use today?3. List all seven taxa in order from

SMALLEST to LARGEST.4. Which taxon contains more

organisms; a family or a class?

Did you know…

• Oysters change their sex several times over their lifetime.

Warm Up #2

• Name a few problems with early classification efforts.

Did you know

• If you could drive your car straight up you would arrive in space in just over an hour.

Warm Up #3

For the vocabulary words below, state the major difference between the words and give an example for each word.

1. autotroph/heterotroph2. Prokaryote/eukaryote3. Unicellular/multicellular4. Anaerobic/aerobic

• Female black widow spiders eat their males after mating.

Warm Up #4

1. How many domains are there?2. Which is larger a kingdom or a

domain?3. If two organisms are in the same

family, list all of the other taxa they are also classified in together.

Kingdoms

EubacteriaArchaebacteriaProtistaPlantaeFungiAnimalia

DOMAIN EUKARYADOMAIN

ARCHAEA