Transcript Dicotomus key

Classification
In order to make their job easier,
scientists classify living things into
groups, based on how they are the
same, and how they are different.
What is Classification?
Classification arranges
objects, ideas,
or information
into groups by finding
common
traits or characteristics.
The Science of Classification
Scientist who classify or
organize organisms
(animals and plants)
are called taxonomists.
Taxonomists study taxonomy.
The History of Organization
Aristotle 384-322 BC
Interested in biological classification.
Patterns in nature.
Carl Linnaeus
1707-1778 ACE
Father of
Biological
Classification!
Binomial Nomenclature
Two-word naming system
– Genus
• Noun, Capitalized,
Underlined or Italicized
– Specific epithet
• Descriptive, Lower Case,
Underlined or Italicized
– Together they are the
species name.
• Without the genus name,
the specific epithet is
meaningless
Common name: Robin
• Erithacus rubicula
• Turdus migratorus
Common name: Black and Polar Bear
Ursus americanus
Ursus maritimus
Why not use common names?
• Scientists avoid
using common
names because
they are often not
specific to a
particular species
and can be
confusing.
• Different countries (and
different regions within
countries) have different
common names for the same
organisms
•
Common names such as blue
crab, redfish, and dolphin are
successfully used in casual
communication, and convey an
immediate idea of what a
particular animal or plant looks
like.
Groups are also arranged in
hierarchical order.
Hierarchical Classification
• Taxonomic categories
– Domain (big)
– Kingdom
– Phylum
– Class
– Order
– Family
– Genus
– Species (small)
Dear
King
Philip
Came
Over
For
Good
Soup
What are Dichotomous Keys?
• a method for determining the identity of
something (like the name of a butterfly, a
plant, a lichen, or a rock) by going through
a series of choices that leads the user to
the correct name of the item.
• Dichotomous means "divided in two parts".
Using a dichotomous key
At each step of the process of using the key, the user is
given two choices; each alternative leads to another
question until the item is identified.
1a. If the leaves are flat….go to question 4.
1b. If the leaves are needle-like….go to question 2.
2a. Are the needles in a bunch? Go to question 5
2b. Are they spread along the branch?“…pine tree
Eventually, when enough questions have been
answered, the identity of the tree is revealed.
Quiz
tomorrow!!!!!!!
1. Start by observing the group of things to be
used in the key.
2. List the most general traits that can be used to
divide the organisms into categories.
3. create a series of numbered steps with the first
step showing the first characteristic you used.
At each step, offer two choices for classifying
the beetle based on a single characteristic.
4. There should be one less step than the total
number of organism to be identified in your
dichotomous key.