Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
1
ClassificationChapter 9
Sorting It All Outsection 1
2
Why Classify?Classification
Is the division of organisms into groupsor classes based on common characteristics
For thousands of years, humans haveclassified living organisms based on usefulness
Some biologists classify living and extinct organisms
Scientists classify organisms to help make sense andorder of the living things in the world
Biologists use a system to classify living thingsgroups according to characteristics shared
3
Classifying things makes it easier to answer questions about:
How many known species are there?What are the defining characteristics?What are the relationships between the species?
How Do Scientists Classify Organism?Before 1600's, scientists divided organisms into 2 groups
plantsanimal
As more organisms were discovered, they didn't fit into these categories
In the 1700's, a Swedish scientist named Carolus Linnaeus founded modern taxonomy
4
Taxonomy is the science of describing, classifying and naming living things
Linnaeus tried to classify living things based on their shape and structure
described a 7 level system of classificationstill used today
Classification TodayTaxonomists use the 8 level system to classifyliving things based on shared characteristics
Scientists also use these characteristics to alsohypothesize how closely organisms are related
5
Branching DiagramsIn branching diagrams, several characteristicsare listed along a line
Characteristics are shared by the animals to the right of it
ability to purr
retractable claws
give birth to live young
hair and mammary glands
platypus
6
7
Levels of ClassificationEvery living thing is classified into one of 6
kingdomsDomains largest, most general groupKingdoms domains are sorted in kingdomsAll living things in a kingdom are sorted intoPhyla ( phylum)
members in one phylum are alike and different from the other phylums
Phylum are sorted into classesClasses are separated into ordersOrders are separated into familiesFamilies are broken into genera (genus)Genus is broken into species
A species is a group of organisms that are closely related and can mate to produce fertile offspring
ex. house cat (pg. 225)
KingdomPhylumClassOrderFamilyGenusSpecies
KingPhillipCameOver ForGreat Spaghetti
8
Scientific NamesBy classifying organisms, biologists are able
to give organisms scientific names
A scientific name is always the same regardless of what the common name may be
Before Linnaeus, names were 12 words long and were often different among scientists
9
Two Part NamesLinnaeus simplified the naming of living
things by giving each species a twopart scientific name
First part is the genusSecond part is the species
example; Asian elephantElephas maximus
No other species has both genus and speciesNaming rules help scientists communicate
clearly about living things
All scientific names :genus names begin with a capital letterspecies names are lowercaseboth words are underlined or italicizedusually in Latin or Greekmay contain information about the organism
ex Tyrannosaurus rex"Tyrannosaurus" two Greek words
meaning tyrant lizard"rex" in Latin means king
10
Dichotomous KeyTaxonomists have developed special guides tohelp scientists identify organisms
dichotomous keyis an identification aid that uses sequential pairs of descriptive statements
there are only 2 alternative responsesperson trying to identify chooses the
correct oneit either identifies the organism or
leads to another statementby working through the statements,
an organism can be identified
11
A Growing SystemPeople are still discovering and classifying new organisms
some will fit into existing catergoriessometimes new evidence doesn't fit and a new
category is madeexample: Symbion pandora
found on lobster's lipsdidn't fit an known groupscientists made a new phylum