Classifying Living Things
Classifying Living Things


Scientists identify, define, and name species of organisms
A species is a group of organisms that share similar physical
features, are genetically similar, and can reproduce with one another
to produce a viable offspring.
Why this is important

Accurately names organisms

Prevents duplicated names

Prevents misnomers (E.g. starfish & jellyfish arent’ fish)

Universal language (latin)

To show evolutionary relationships
Taxonomy



An organism is a living thing that is capable of
reproducing, responding to stimuli, and growth.
All organisms in the world can be classified into a
grouping system known as Taxonomy.
Taxonomy was initially created by Carl Linnaeus.
Taxonomy
How many species are there?



About 1.4 million have been identified
Nearly 2/3 are insects
Scientists estimate 10-100 million (meaning most
aren’t even discovered yet)
Thought Experiment

Imagine you were in charge of naming all living
organisms. How might you divide these organisms?
Taxonomy

Was created by examining physical and structural
features :
 The
more features in common, the closer the ancestral
relationship

Binomial nomenclature is the system used to name
every organism.
E.g. Canis lupus
(Grey Wolf)
Binomial Nomenclature

Binomial nomenclature is usually based on a
characteristic of the organism
 E.g.
Castor canadensis
(i.e. it is from Canada)

The first word Castor is known as the genus name
and the second word canadensis is known as the
species name.
*Note that the genus name is always capitalized while the
species is not. Also the entire name is italicized.*
Levels of Classification



The Genus and Species names are
part of the 8 ranks
The image on the left shows the
different levels of classification (i.e.
ranks)
If two organisms have the same
genus name they are more similar
than two organisms with the same
phylum name
Dearest King Philip Came Over For Good Spaghetti
Levels of Classification
Taxon
Side Note: Taxon (Plural
= Taxa) is a specific rank
for organisms
I.e.
Rank = Kingdom
Taxa = Animalia
E.g. Human Classification


The common name is often used to name a species.
The Kingdom level is the most general while the Species is
most specific
Common Name: Humans
Scientific Name: Homo sapiens
Classification Level
Kingdom
Phylum
Class
Order
Family
Genus
Species
Classification Name
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
sapiens
Which two organisms are most closely
related?
Classification Level
Humans
Grey Wolf
Brown Bear
Kingdom
Animalia
Animalia
Animalia
Phylum
Chordata
Chordata
Chordata
Class
Mammalia
Mammalia
Mammalia
Order
Primates
Carnivora
Carnivora
Family
Hominidae
Caninae
Ursidae
Genus
Homo
Canis
Ursus
Species
sapiens
lupus
arctos
Levels of Classification
There are 3 Domains and 6 Kingdoms
The Domain: First level of Classification
 This level breaks down living organisms into the
major categories of:

1.
Bacteria
2.
Archaea
3.
Eukarya
Eukaryotes
Prokaryotes



Do not have a nucleus
Do not have well defined organelles
E.g. Bacteria and Archaea
Eukaryotes


Have a nucleus
Have well defined membrane-bound organelles
The Kingdom Taxa

The six Kingdom system is commonly used: bacteria,
Archaea, Protista, Fungi, Plantae, Animalia
The Other Taxa

Taxa for the Grey Wolf (Canis lupus)
What Makes a Species a Species

Lions and tigers can reproduce together and make
a liger or tigon. Why then are they considered
different species?
+
What Makes a Species a Species


Recall: A species is a group of organisms that look
similar and can can interbreed under natural
conditions to produce fertile offspring.
In other words, their children can grow and
reproduce.
 Ligers
and tigons cannot reproduce
Video of Liger

https://www.youtube.com/watch?v=1zOWYj59BXI
Homework

Read pages 10-30
#2-6 (p.13); Activity 1.1 (p.13); #2-3, 6-7, 9-10
(p.16); #9,11(p.19); #1-2, 4-7, 9 (p.30)