This document discusses the classification of organisms. It explains that scientists classify living things to organize and study them more easily. Early systems like Aristotle's grouped animals based on how they moved, but Linnaeus improved on this by classifying organisms according to observable features. His system uses binomial nomenclature, giving each organism a two-part scientific name. Organisms are classified into seven main levels from broadest (kingdom) to most specific (species). The document provides an example of classifying a brown squirrel through these seven levels.

1. Chapter 6
Section 1
Classifying Organisms

2. Why do scientists classify living
organisms into groups?
• Classification-The process of grouping
things based on their similarities.
• Scientists use classification to organize
living things into groups so that they are
easier to study.
• Taxonomy-The scientific study of how
living organisms are classified.

3. What are the Values of
Classification?
• It aids in the identification of species
• Shows links between organisms,
• Predicts characteristics shared by similar
species
• EX:If I tell you there is a newly discovered
animal that looked like an alligator, what
would that animal look like?

4. Describe these three animals

5. Early Classification Systems
• Aristotle was the first scientist to develop a
classification system for organisms.
• He divided animals into three groups: Those
that fly, those that swim, and those that walk,
crawl or run.
• He then further divided these groups into
subgroups such as by where they live.
• Which groups would the previous three animals
fall under?
• What is the problem with this system?

6. As you could see that even though all the
organisms in a group moved in a similar way, they
were different in many other ways. Aristotle then
used there differences to further divide each group
into subgroups. Smaller groups of organisms that
shared other similarities.

7. Early Classification Systems
continued.
• Carolus Linnaeus was a Swedish scientist
who expanded on Aristotle’s idea of
classification.
• He placed them in groups based on their
observable features.
• He devised a naming system called
Binomial nomenclature where each
organism is given a two-part name.

8. Binomial Nomenclature
(by NOH mee ul NOH men klay chur)
• This two-part naming system is made up
of the genus and species name.
• The genus name is always capitalized
and the species name is either written in
italics or underlined.
• EX: Felis domesticus
• Most scientific names are Latin. Why do
you think they are written this way?

9. What are the Seven Levels of
Classification?
• The seven levels of classification are
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species
• First an organism is placed in a broad group (Kingdom is
the broadest level), which in turn is divided into more
specific groups.
• The more classification levels that two organisms share,
the more characteristics they have in common.
• We are going to classify a brown squirrel.

10. Kingdom
• Kingdom (Animalia, or “animal”).
• Largest groups that living things are sorted
into.

11. Phylum
• Phylum (Chordata, or “has a backbone”)
• Second largest group classification.

12. Class
• Class (Mammalia, or “has a backbone and
nurses its young”)
• As you can see, the more levels of classification
we use the more pictures (or organisms) that are
eliminated.

13. Order
• Order (Rodentia, or “has a backbone,
nurses its young, and has long, sharp
front teeth)

14. Family
• Family (Scuridae, or “has a backbone,
nurses its young, has long, sharp front
teeth, and has a bushy tail)

15. Genus
• Genus (Tamiasciurus, or “has a
backbone, nurses its young, has long,
sharp front teeth, has a bushy tail, and
climbs trees)

16. Species
• 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. How can you remember all of the
levels?
• A mnemonic phrase is a creative phrase used to aid
memory.
• Have you ever used a mnemonic device such as
ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo,
Violet)?
• To remember the seven kingdoms, I could create the
sentence King Phillip Calls Out, “Fried Great Swordfish.”
• The first letter in each word represents a different
kingdom. Don’t like this sentence? Create you own.
• Create your own mnemonic device at the bottom of your
paper. When everyone is finished we will share your
ideas.
Kingdom , Phylum, Class, Order, Family, Genus, Species

18. Taxonomic and dichotomous
keys
• A taxonomic key is a series of paired
statements used to describe the physical
characteristics of unfamiliar organisms.
• A dichotomous key is a detailed key for
determining the identity of something (like the
name of a bird, a plant, or a fish) by going
through a series of choices that leads the user to
the correct name of the item.

19. Review Questions
• Get out a sheet of paper and answer
these questions without your notes.
• 1. Why do scientists classify organisms?
• 2. What are the three major groups of
animals in Aristotle’s classification
system?
• 3. How did Carolus Linnaeus classify
organisms?
• 4. Which system is more useful today?