Taxonomy - the science of classifying organisms
Common Names
spider monkey
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sea monkey
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sea horse
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gray wolf
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Firefly
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Crayfish
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mud puppy
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horned toad
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Ringworm
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black bear
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Jellyfish
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*Common names can be confusing and names can vary by region.
Why Classify?
About 1.5 million species named
2-100 million species yet to be discovered
Taxonomy =science of classifying organisms
--groups similar organisms together
--assigns each a name
Naming Organisms:
Organisms have common & scientific name -all organisms have only 1 scientific name
-usually Latin or Greek
-developed by Carolus Linnaeus
The scientific name is always italicized or underlined. Genus is capitalized. Species is not. Scientific names can be abbreviated by using the capital letter of the genus and a period: Example.P. leo (lion)
Members of the same genus are closely related. Only members of the same species can interbreed (under natural conditions) Some hybrids do occur under unnatural conditions: Ligers are crosses between tigers and lions.
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This two-word naming system is called
Binomial Nomenclature
-written in italics (or underlined)
-1st word is Capitalized --Genus
-2nd word is lowercase ---species
Examples: Felis concolor, Ursus arctos, Homo sapiens,Panthera leo , Panthera tigris
Linneaus - devised the current system of classification, which uses the following schema
Kingdom
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Phylum/Division
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Class
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Order
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Family
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Genus
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Species
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Human
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Cougar
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Tiger
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Pintail Duck
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Kingdom
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Animalia
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Animalia
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Animalia
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Animalia
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Phylum/Division
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Chordata
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Chordata
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Chordata
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Chordata
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Class
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Mammalia
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Mammalia
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Mammalia
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Aves
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Order
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Primate
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Carnivora
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Carnivora
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Anseriformes
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Family
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Homindae
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Felidae
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Felidae
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Anatidae
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Genus
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Homo
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Felis
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Panthera
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Anas
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Species
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sapiens
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concolor
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tigris
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Acuta
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18-2 Modern Evolutionary Classification
- Linnaeus grouped species mainly on visible similarities & differences
- Today, taxonomists group organisms into categories that represent lines of evolutionary descent (phylogeny)
- Evolutionary relationships among a group of organisms can be shown on a cladogram
Similarities in DNA and RNA
- DNA & RNA is similar across all life forms
- Genes of many organisms show important similarities at the molecular level
- DNA shows evolutionary relationships & helps classify organisms
The Six Kingdoms and Domains
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number of Cells
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Energy
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cell type
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Examples
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archaebacteria
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Unicellular
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some autotrophic, most chemotrophic
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Prokaryote
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"extremophiles"
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Eubacteria
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Unicellular
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autotrophic and heterotrophic
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Prokaryote
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bacteria, E. coli
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Fungae
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most multicellular
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Heterotrophic
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Eukaryote
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mushrooms, yeast
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Plantae
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Multicellular
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Autotrophic
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Eukaryote
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trees, grass
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Animalia
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Multicellular
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Heterotrophic
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Eukaryote
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humans, insects, worms
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Protista
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most unicellular
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heterotrophic or autotrophic
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Eukaryote
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ameba, paramecium, algae
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Using Dichotomous Keys
A dichotomous key is a written set of choices that leads to the name of an organism. Scientists use these to identify unknown organisms.
Consider the following animals. They are all related, but each is a separate species. Use the dichotomous key below to determine the species of each.
1.
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Has green colored body ......go to 2
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Has purple colored body ..... go to 4
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2.
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Has 4 legs .....go to 3
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Has 8 legs .......... Deerus octagis
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3.
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Has a tail ........ Deerus pestis
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Does not have a tail ..... Deerus magnus
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4.
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Has a pointy hump ...... Deerus humpis
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Does not have a pointy hump.....go to 5
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5.
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Has ears .........Deerus purplinis
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Does not have ears ......Deerus deafus
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