Download Essential Question: How do biologists classify organisms?

Topic: The Biological Classification System
Essential Question: How do
biologists classify organisms?
In 2008, Usain Bolt set the world record
for the 100 meters with one shoelace
undone.
3/25/16
Taxonomy
Why would biologists need to classify
living things?
• Think of three reasons. Share your reasons with
your neighbor.
Classification of living things
To be useful, it helps to create a
system – just like you did with the
seashells.
Let’s see how well your systems
work.
Get a set of shells and you will be
given a classification by another pair.
• Pick out a few shells and try using the system made
by someone else.
• Find something about the system that you think
works well – write a sentence explaining this on the
paper itself.
• Write down one thing you would change and/or
improve – and why.
• Sign it and return to original creators.
Essential Question: How do you group
organisms in an organized way?
On Wednesday’s page, under the
picture of your system, answer the
essential question. Put an outline
around it to make it easy to find later.
* Important note- the system of
classification is man-made and is
constantly being changed by
taxonomists as new organisms are
found or new information is learned
(such as similarities in DNA). But
the system is based on real
relationships.
The First “Taxonomist”
The first scientist to develop a system of
classification was Aristotle – in the
fourth century B.C.
He divided animals into three groups:
Those that fly
Those that swim
Those that walk, crawl, or run
Then he divided these groups in to
smaller groups.
Then he divided these groups in to
smaller groups.
Early classification systems
• In the 1750’s, a Swedish
scientist named Carolus
Linnaeus sought to improve
Aristotle's system.
• He placed organisms in groups
based on observable
characteristics.
• He devised a naming system
for organisms so people could
not confuse different
organisms.
The system is called
“Binomial Nomenclature”
• Each organism is given a twopart name.
• The first part is the genus – a
grouping of similar, closely
related organisms.
• For example, the cat family is
the genus Felis.
• Pumas, ocelots, and house cats are all in the genus
Felis and share characteristics such as retractable
claws and hunting behaviors.
The second part of the name is the
species name.
• A species is a group of similar
organisms that can mate and
produce fertile offspring.
• The species name often
describes a distinctive feature
of the organism.
• This organism is Felis concolor.
Felis concolor
Genus name (first)
species name
• Underlined (or in italics)
• Genus capitalized
• species not capitalized
Using Scientific Names
• When you identify any organism, you
must use both the genus and the species
names together.
• Thus, Homo sapiens (humans), not just
sapiens.
Felis domesticus
Felis concolor
Today,
• Classification takes evolution into account.
• Species with more similar evolutionary history are
classified more closely together.
• How do we know?
• Much of the information comes from genetics.
Levels of Classification
Taxonomists group organisms into seven basic levels –
from broad, general groups down to very specific
groups. The more levels two organisms share, the
more similar they are.
Kingdom
Phylum
Class
Order
Family
Genus
Species
Kingdom
More types of living
things
Phylum
Class
Order
Family
Genus
Species
Fewer types of
living things
Kingdom
Phylum
Class
Order
Family
Genus
Species
Kingdom
Phylum
Class
Order
Family
Genus
Species
Kings
Play
Chess
On
Friday
Generally
Speaking
Classification levels are still changing.
• Levels