17.1 The Linnaean System of Classification
KEY CONCEPT
Organisms can be classified based on physical
similarities.
17.1 The Linnaean System of Classification
Aristotle was the first scientist to create a classification
system (around 3000 BC), which included two branches:
Plants
herbs
shrubs
Animals
trees
land
air
water
17.1 The Linnaean System of Classification
* Linnaean classification
- Linnaeus (around
1700s) created our
modern day
classification system
that groups organisms
based on physical
characteristics
17.1 The Linnaean System of Classification
- taxonomy is the science of naming and classifying
organisms
White oak:
Quercus alba
~ a taxon is a group of organisms in a classification
system
17.1 The Linnaean System of Classification
- binomial nomenclature is a scientific naming system that
gives all organisms two names = genus and species
– uses Latin words
– scientific names are always written in italics
17.1 The Linnaean System of Classification
• A genus includes one or more physically similar species.
– Species in the same genus are thought to be closely
related.
– Genus name is always capitalized.
• A species descriptor is the second part of a scientific name.
– always lowercase
– always follows genus
name; never written alone
Tyto alba
17.1 The Linnaean System of Classification
Ex:
a human’s binomial nomenclature is
Homo sapien
17.1 The Linnaean System of Classification
Scientific naming is used since common names can be
confusing since they differ according to country, language,
region, religious backgrounds, etc.
United States calls this corn
Germany
(korn) = grains of any kind
Scotland = oats
England = wheat or grains
of any kind
17.1 The Linnaean System of Classification
~ scientific names help scientists to communicate
– Some species have very similar common names.
– Some species have many common names.
17.1 The Linnaean System of Classification
Linnaeus’ classification system has seven levels.
currently there are 8!
• each level is
included in the
level above it
• levels get
increasingly
specific from
kingdom to
species
17.1 The Linnaean System of Classification
Kingdom (Animalia, or "animal")
Phylum (Chordata, or "has a backbone")
Class (Mammalia, or "has a backbone and nurses its
young")
Order (Rodentia, or "has a backbone, nurses its young, and has long, sharp
front teeth)
Family (Scuridae, or "has a backbone, nurses its young, has long, sharp front
teeth, and has a bushy tail)
Genus ( Tamiasciurus , or "has a backbone, nurses its young, has long, sharp
front teeth, has a bushy tail, and climbs trees)
Species ( hudsonicus , or "has a backbone, nurses its young, has long, sharp
front teeth, has a bushy tail, and has brown fur on its back and white fur on its
underparts)
17.1 The Linnaean System of Classification
largest
DOMAIN
- uppercase
smallest
- lowercase
17.1 The Linnaean System of Classification
How can we remember the levels of classification?
17.1 The Linnaean System of Classification
The Linnaean classification system has limitations.
• Limits to system = doesn’t account for molecular
evidence
(technology didn’t exist during Linneaus’ time, so his
system based only on physical similarities)
17.1 The Linnaean System of Classification
• physical similarities are
not always the result of
close relationships
• genetic similarities more
accurately show
evolutionary relationships
Red panda