ClassificationChapter 17

Why classify organisms?currently there are 1.5 million known

species of living things

Taxonomyfield of science that deals with classifying

organisms according to their characteristics and evolutionary history

Early Classification

Aristotle – 2000 BC

devised a classification system

• divided living things into 2 groupsPLANTS – divided into smaller groups based on

their stem structure – herbs, shrubs, trees

ANIMALS – divided into smaller groups based on their habitat – land, air, water

Early Classification

Linnaeus - 1700’s - naturalist• devised a classification

system based on comparative morphology

• classification system had 7 taxonomic categories

(called TAXONS)

• devised a way to give each organism a unique 2 word name

7 taxonomic categories

• Kingdom – largest group; most variety

• Phylum/Division

• Class

• Order

• Family

• Genus

• Species – smallest group; least variety

ACRONYM

• kingdom - KING• phylum - PHILLIP• class - CAME• order - OVER• family - FROM• genus - GREAT• species - SPAIN

American Crow

• Kingdom: Animalia

• Phylum: Chordata (with backbones)

• Class: Aves (birds)

• Order: Passeriformes (songbirds)

• Family: Corvidae (crows, jays)

• Genus: Corvus

• Species: brachyrhynchos

What do these animals have in common?

Why classify bats and birds together but not include dragonflies?

Answer this….

Would a horse and a zebra belong to the same species? Why or why not?

Might they be members of the same genus? Why or why not?

Would a dog and a wolf belong to the same species? Why or why not?

Might they be members of the same genus? Why or why not?

Binomial Nomenclature

• giving an organism a 2 word name, A SCIENTIFIC NAME

consists of two words Genus – 1st word –

capitalizedspecies – 2nd word – lower case

*written in latin *underlined or italicized

Why Latin?

• “dead” language – no changes being made– it is not in use today

• is the basis for many of today’s languages

• assures a unique name for each species

Names may tell you…

• Name of geographic location

• Who discovered it

• The look of the organism

• Example:– Linnea borealis– Odocoileus virginianus– Felis domesticus

Lasionycteris noctivagans

• nocti = nocturnal• vagans = wanderer• nyct = night

“wanderer at night”

Silver-haired bat

Dichotomous Key“dividing into two parts”

• used to help identify an organism based on it characteristics

• at each step in a dichotomous key you have 2 choices

MODERN CLASSIFICATION

Today, taxonomists classify organisms in such a way as to indicate evolutionary relationships.

Archaeopteryx – believed to be the ancestor of birds

Modern TaxonomyIS NOT BASED ON HABITAT!!!!

Today, taxonomists use…• comparative morphology• fossil evidence• embryological evidence• chromosomal evidence• biochemical similarities• physiological similarities• evolutionary relationships

to determine the classification of an organism

Other Changes…

sometimes, more than 7 categories are needed….

SUBCATEGORIES CAN BE USED…

subkingdom subphylum subclass suborder subfamily subgenus subspecies

DERIVED CHARACTERS are used to help determine evolutionary relationships

Derived Character - a feature (trait) that apparently evolved only within a specific groups of organisms

such as - jaws, lungs, claws, feathers, mammary glands,….

Cladogramdiagram made by cladistic analysis that shows the

evolutionary relationships of organisms

2 Modern Systems of Classification

3 domain system 6 kingdom system Domain archaea Kingdom archaebacteria Domain bacteria Kingdom eubacteria Domain eukarya Kingdom protista

Kingdom fungi Kingdom plantae Kingdom animalia

Differences among KingdomsArchaebacteria and Eubacteria: prokaryotic,

unicellular

Protista: eukaryotic, unicellular and multicellular

Fungi: eukaryotic, cell wall of chitin, no chloroplasts, unicellular and multicellular, heterotrophic

Plantae: eukaryotic, cell wall of cellulose, chloroplasts, all multicellular, autotrophic

Animalia: eukaryotic, no cell wall, all multicellular, heterotrophic

Kingdoms

Archaebacteria and Eubacteria (previously classified together as kingdom Monera)

Bacteria….Eubacteria and Archaebacteria

• many are saprophytic (feed on dead organic matter) • many are parasitic (feed on living organic matter)• among the first forms of life • prokaryotic

ONLY KINGDOMS lacking an organized nucleus and membrane-bound organelles

Nostoc (cyanobacterium)

Methods of energy acquisition

• Chemosynthesis

• photosynthesis

• heterotrophic

Kingdom Archaebacteria (“old bacteria”)

• prokaryotic

• cell wall does not contain peptidoglycan

• have unusual lipids in cell membrane

• oldest and most primitive organisms known

• life’s extremists - occupy environments that “normal” organisms find too harsh

Archaebacteria….3 groups….

Methanogens - produce methane gas, found in soil, swamps, digestive tracts of animals

Extreme Halophiles – live in high salt environments, found in salt lakes, Dead Sea

Thermoacidophiles – live in hot, acidic environments, found in volcanic vents, hydrothermal vents

Kingdom Eubacteria (“true bacteria”)

• cell wall contains peptidoglycan

• includes most of the bacteria that affects our daily life including….

tetanus, strep throat, tooth decay,

E. coli, salmonella, botulism,

lyme disease, syphilis, and many more….

• some capable of chemosynthesis, some photosynthesis, others are heterotrophic

Bacteria – Roles in Ecosystem• can cause disease• photosynthesis and oxygen production

– cyanobacteria (“blue-green bacteria”) contributed to formation of atmospheric oxygen by photosynthesis

• food source• nutrient transfer

– convert atmospheric N into forms useable forms for plants and animals

• decomposition– saprophytic (decompose dead tissue)– symbiotic (live within a host organism)

• some oil deposits are attributed to cyanobacteria

Kingdom Protistaalgae, protozoa, fungus-like protists

Protista• Animal-like (protozoan), plant-like (algae) and

fungus-like protists • heterotrophic and autotrophic• eukaryotic• freshwater, saltwater, soil• because of great diversity,

classification is difficult

Eukaryotes that are NOT fungi, animals, or plants!

paramecium

Protista…. 3 groups….

Protozoa (“first animal”)– “animal like”, single-celled, motile, heterotrophic – digest food by engulfing, digesting, and absorbing it

Algae – “plant like”, single-celled or colonial or multicellular– diatoms, algae, dinoflagellates,…

Fungus Like Protists

- “fungus like”, includes slime molds and others

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDiversity_3.html

Protista – Roles in Ecosystem• photosynthesis and oxygen production• food source (algae)

– animal feed, fertilizers– algae sheets used in some Japanese dishes– additive to puddings, ice cream, salad dressing,

candy (carrageenan and alginate)

• can cause disease– avian malaria, human malaria,

amoebic dysentery

Protista and Red Tides• population

explosion of dinoflagellates

• neurotoxin released

• shellfish concentrate toxin

• humans can be killed by eating shellfish contaminated by toxin

http://www.redtide.whoi.edu/hab/rtphotos/noctiluca.jpg

Kingdom Fungimushrooms, blights, rusts, molds, puffballs, morels,

yeasts, truffles, toadstools, shelf fungi,….

Fungi

• eukaryotic• made up of hyphae • mycelium=mass of hyphae• no roots, stems or leaves• no chlorophyll• saprophytic or parasitic• reproduce by spores• cell walls contain chitin• absorptive heterotrophs• multicellular and unicellular species

Roles in Ecosystem• Food Source

– mushrooms, truffles, morels, cheeses, bread, beer and wine

• Production of some Antibiotics• Crop Parasites

– cause loss of food plants, spoilage, infectious disease

• Dutch Elm Disease • Chestnut Blight

• Benefit Wildlife – food source, nest sites, hiding places

and cover• Symbiosis - Mutualism

– lichens (fungus + alga)– mycorrhizae (fungus and plant roots)

Kingdom Plantae

Plants

• eukaryotic, multicellular, photoautotrophs• cell wall with cellulose

2 major groups of plantsnonvascular and vascular

Nonvascular Plants• small (lack conducting cells)• likely were the earliest land plants• liverworts, hornworts and mosses

Vascular Plants

• have specialized cells for transporting materials • Xylem (for transporting water and mineral nutrients)• Phloem (for transporting sugars from leaves to the

rest of the plant)

• pines, cacti, grasses, trees, flowers, …..

American chestnut, late 1800s

Plants – Roles in Ecosystem• food source• generate oxygen• provide habitat for humans and wildlife

Kingdom Animalia

•multicellular •heterotrophic•eukaryotic•no cell wall

2 main groupsinvertebrates and vertebrates

Invertebrates(animals without a backbone)

sponges, jellyfish, corals, sea anemones, scallops, oysters, snails, octopi, squid, sea urchins, sea stars, spiders, scorpions, crabs, shrimp, insects, worms, rotifers, comb jellies,…

Vertebratesanimals with a backbone (of bone or cartilage)

fish, amphibians, reptiles, birds, mammals

Let’s Review

This characteristic separates which kingdoms….• All members are heterotropic?• All members are autotrophic?• Contains both heterotrophic and autotrophic members?• All members prokaryotic?• All members eukaryotic?• Have chloroplasts?• Have a cell wall?• All members unicellular?• All members multicellular?• Contains both unicellular and multicellular members?