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 = KingdomTaxa = Animalia

E.g. Human Classification

Common Name: HumansScientific Name: Homo sapiens

Classification Level Classification NameKingdom AnimaliaPhylum ChordataClass MammaliaOrder PrimatesFamily HominidaeGenus HomoSpecies sapiens

The common name is often used to name a species.

The Kingdom level is the most general while the Species is most specific

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 KingdomsThe 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?

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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)