1. Classification of Living Things

2. How Are Living Things Classified?
How many different kinds of plants and animals can you name? Twenty? Thirty? Fifty? It may be hard to believe, but we share this planet with millions of different kinds of organisms! So far, about 1.3 million species have been identified, and 15,000 are being discovered each year!

3. How do we keep track of all these organisms?
Biologists classify living things into groups
Members of the same group are alike in certain important ways
The science of classifying living things is called taxonomy

4. Organisms are Classified According to…

5. Similarities in Physical Characteristics

6. Cellular Organization
Some organisms are single-celled and some organisms are multicellular

7. Genetic Makeup
Scientists look at the organisms protein and DNA

8. Common Ancestors

9. The Way an Organism Develops Before it is Born
Also called comparative embryology

10. Categories of the Classification System
There are seven categories within the classification system
The broadest is called the Kingdom
We identify six kingdoms:
Plants
Animals
Protists
Fungi
Eubacteria
Archaebacteria

11. Further Classification
Each kingdom is then divided into smaller and smaller groups
Think of the classification system as an upside down pyramid

12. Further Classification
As you move further down the pyramid, each “room” or category gets smaller. It can hold fewer and fewer members.
However, the members have more traits in common and begin to be more alike.

13. What is a Species?
The species is the smallest group in the classification pyramid
It is only large enough for one kind of organism (ex: humans, elm trees)
Members of a species look alike and can reproduce, producing fertile offspring

14. Tracing Similarities
A member of a particular classification group has traits that are the same as:
All members of its group
All members of the broader classification groups above it in the pyramid
Example: All members of a particular class has traits that are similar to all members of that class, as well as all members of its phylum and kingdom

15. Classification of a Brown Bear

16. Classification of a Human

17. Binomial Nomenclature
The modern classification system we use was developed by Carolus Linneaus
In his system, each species is identified by two Latin names
Genus- first part of an organisms name (uses a capital letter)
Species- second part of an organisms name (uses a lower case letter)
Homo sapien (human)
Canis lupus (gray wolf)

20. Dichotomous Keys
In order to classify organisms, you must first identify them
A dichotomous key is a device for identifying an object unknown to you, but know to others
The user of the key makes choices between alternative characteristics of the unknown object
Each choice leads down a separate path until the use arrives at the name of the object!