Chapter 18

Classification

Organization and naming systems based on morphology and genetics

Humans have a tendency to see commonalities and differences,

clustering images by appearance.

Aristotelian classification

Life

Plant Animal

Herb Shrub Tree Aristotle grouped organisms based on appearance and abilities.

Why Classify?

• To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner.

• To avoid the confusion caused by regional common names.

Texas bluebonnet (Lupinus texensis )

Taxonomy

– the science of classification– Uses Latin…descriptive, universal,

“dead” language that never changes– Uses binomial nomenclature

• Two word naming system of Genus & species = scientific name

– Uses hierarchy of categories from general to specific

Common names

• Many people refer to organisms by common names rather than scientific names.

• Be careful that common names do not always reflect the biology of the organism.

• Example: starfish are not “fish”

Comparing related animals

• Lynx rufus, lynx

• Panthera concolor, mountain lion

• Lynx canadensis, bobcat• Which two are more related?

How do you know?

Mountain lion

BobcatLynx

Dichotomous key: system to identify organisms and their

scientific names

• A key is made up of sets of numbered statements.

• Each set deals with a single characteristic of an organism, such as leaf shape or arrangement.

Carolus Linnaeus (1707-1778)

• Created a classification system with seven hierarchical levels

• Kingdom• Phylum• Class• Order • Family• Genus• species

Human classification:Kingdom Animalia

PhylumChordata

ClassMammalia

OrderPrimates

FamilyHominidae

GenusHomo

speciessapiens

Grizzly bear Black bearGiant panda Red fox Abert

squirrelCoral snake Sea starKINGDOM Animalia

PHYLUM Chordata

CLASS Mammalia

ORDER Carnivora

FAMILY Ursidae

GENUS Ursus

SPECIES Ursus arctos

Classification of Human and Chimp

Level Human Chimp

Kingdom Animalia Animalia

Phylum Chordata Chordata

Class Mamalia Mamalia

Order Primate Primate

Family Hominidae Pongidae

Genus Homo Pan

species sapien troglodytes

Kingdom…Phylum…Class…Order…Family…Genus species…(variety) or (breed)

Phylogeny

• Studying the evolutionary history and relationships of organisms

Cladograms• Making a Family Tree

• Represent evolutionary relationships, phylogeny, and not just physical appearances

Cladograms• Cladistics: a phylogenic study that

assumes how groups of organisms diverged and evolved

Theropods

Allosaurus

Sinornis

Velociraptor

Archaeopteryx

Light bones3-toed foot;

wishboneDown

feathersFeathers withshaft, veins,and barbs

Flight feathers;arms as long

as legs

Traditional classification vs. Cladograms

CLASSIFICATION BASED ON VISIBLE

SIMILARITIES

CLADOGRAM BASED ON DERIVED

CHARACTERS

Appendages Conical Shells

Crab Barnacle Limpet Crab Barnacle Limpet

Crustaceans Gastropod

Molted exoskeleton

Segmentation

Tiny free-swimming larva

Current six-kingdom classification

• Archaebacteria: prokaryotic

• Eubacteria: prokaryotic

• Protists: eukaryotic

• Fungi: eukaryotic

• Plants: eukaryotic

• Animals: eukaryotic

Modern classification systems include the three-domain system which includes the 6 kingdom system.

• Just a few years ago, all bacteria and some protists were labeled Monera.

Kingdoms

Eubacteria

Archaebacteria

Protista

Plantae

Fungi

Animalia

DOMAIN EUKARYA

DOMAIN ARCHAEA

DOMAIN BACTERIA

Three Domain System

Key Characteristics of Domains and Kingdoms

DOMAIN

KINGDOM

CELL TYPE

CELL STRUCTURES

NUMBER OF CELLS

MODE OF NUTRITION

EXAMPLES

Bacteria

Eubacteria

Prokaryote

Cell walls with peptidoglycan

Unicellular

Autotroph or heterotroph

Streptococcus, Escherichia coli

Archaea

Archaebacteria

Prokaryote

Cell walls without peptidoglycan

Unicellular

Autotroph or heterotroph

Methanogens, halophiles

Protista

Eukaryote

Cell walls of cellulose in some; some have chloroplasts

Most unicellular; some colonial; some multicellular

Autotroph or heterotroph

Amoeba, Paramecium, slime molds, giant kelp

Fungi

Eukaryote

Cell walls of chitin

Most multicellular; some unicellular

Heterotroph

Mushrooms, yeasts

Plantae

Eukaryote

Cell walls of cellulose; chloroplasts

Multicellular

Autotroph

Mosses, ferns, flowering plants

Animalia

Eukaryote

No cell walls or chloroplasts

Multicellular

Heterotroph

Sponges, worms, insects, fishes, mammals

Eukarya

Classification of Living Things

Six Kingdom

classification

Prokaryotic or

eukaryotic

Unicellular or

multicellular

Autotroph or

heterotroph

Archaebacteria

Eubacteria

Protista

Fungi

Plantae

Animalia

Pro Uni both

Pro Uni both

Eu most uni both

Eu most multi hetero

Eu multi auto

Eu multi hetero

Archaebacteria overview• prokaryotic• Most live in extreme

environments such as swamps, deep-ocean hydrothermal vents, and seawater evaporating ponds.

• Most do not use oxygen to respire.

• Examples: Thermophiles, Halophiles, Methanogens

Eubacteria overview• prokaryotic• very strong cell walls• a less complex

genetic makeup than found in archaebacteria or eukaryotes

• diverse habitat• Examples: Strep,

Lacto-bacillus, E. coli

Protist overview• diverse species that share

some characteristics.

• eukaryote

• lacks complex organ systems

• lives in moist environments• diverse metabolism

Protozoans: animal-like protists• Heterotroph: consume organic matter

• Unicellular

• Examples: Amoeba, paramecia

Algae: plant-like protists• Autotroph: uses light to make sugars

through photosynthesis

• Lack roots, stems, and leaves

• Examples: algae, kelp, sea-weed

Fungus-like protists• Decompose dead matter• Motility during some stage of life cycle• No chitin in cell walls

• Examples: Slime-mold, powdery mildew

Fungi overview

• Eukaryotic• Decomposes matter by

absorbing materials• Multicellular or unicellular• Examples: bread mold,

mushrooms, athletes foot, ring worm

Plant overview• Eukaryotic• Multicellular• Photosynthetic:

produce oxygen • Immobile, sessile• Cell walls• Examples: fruit, ferns,

mosses, trees, grasses

Animal overview• Eukaryotic• Multicellular• Mostly mobile• Lack cell walls• Diverse habitats• Examples: lions, tigers & bears,

oh my!

Bacteria

Protista

AnimaliaPlantae Fungi

EuPro

MultiUni

(Seaweeds)

Nutritional types

Auto(photo) Hetero(absorb) Hetero(ingest)

Evolution and the 6 Kingdoms

Six Kingdom

classification

Prokaryotic or

eukaryotic

Unicellular or

multicellular

Autotroph or

heterotroph

Archaebacteria

Eubacteria

Protista

Fungi

Plantae

Animalia

Pro Uni both

Pro Uni both

Eu most uni both

Eu most multi hetero

Eu multi auto

Eu multi hetero

Classification systems video

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Panthera leo? (1)

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Panthera leo? (2)

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