Classification (3.4.2)

Problems with Naming Organisms

Your are probably familiar with the common names of organisms like dogs, cats, worms, jellyfish, oak trees and rockfish.

However, sometimes there can be more than one common name for certain organisms depending on where you live.

Also there can be more than one species with the same common name.

How can we tell the difference between species or know what organism we are talking about?

Problem of the Puma The mountain lion is the largest cat

found in North America. However, the mountain lion has more

than one name depending on who you are talking to.

It is also called the puma, catamount, nittany lion, cougar, or painter.

So, if you don’t know all of the common names, how can you know exactly that someone is talking about a mountain lion?

Felis concolor In order to prevent confusion,

we use scientific names when talking about specific animals.

These names are made up of two Latin or Latinized words.

Now, if you say you are talking about Felis concolor, any person in the world knows exactly what animal you are talking about!

VocabularyTaxonomy Binomial nomenclature

Scientific name Taxon

Kingdom Phylum

Class Order

Family Genus

Species Dichotomous key

Taxonomy Taxonomy is the science of

naming and classifying organisms. Aristotle began grouping

organisms based on their similarities over 2000 years ago.

In 1735, Swedish biologist named Carl Linnaeus came up with a two-word Latinized system of naming organisms based on their similarities.

Linnaeus’ system is called binomial nomenclature.

Binomial Nomenclature

Felis, Musca, domestica, americanus

What’s up with these funny sounding names?

They are either Latin or Latinized words that describe the organism they identify.

What’s Up with Latin!?!

We use Latin because no one speaks Latin anymore.

The words never change their meaning and there is no confusion.

These terms are also descriptive.What do you think the names

domestica and americanus tell us about those organisms?

Binomial Nomenclature Let’s look at a scientific name —Felis

domesticus. Felis is the Genus name and

domesticus is the species name. The Genus refers to a group of closely

related species. In this instance, Felis refers to cats.

The species name only refers to one organism. It is used to describe the organism.

The name domesticus refers to our domesticated house cat.

Rules for Binomial Nomenclature

Names consist of two words—Genus and species.

Both words are italicized or underlined.

Genus is always capitalized. species is always lower-case Both names are in Latin or Latinized. Two different organisms cannot have

the same name. The species name has to be different

within the same Genus.

Scientific NamesHomo sapien

s

Panthera leo

Musca domestic

a

Acer rubrum

People

HouseFly

Lion

Red Maple

ClassificationMost inclusive Kingdom

PhylumClass

OrderFamilyGenus

Most exclusive species

Classification You need to know each level—taxon—of

classification. So, come up with a phrase that helps you

remember the levels in order. I like to use King Philip Came Over For

George’s sword (Kingdom-Phylum-Class-Order-Family-Genus-species)

Remember, each level is called a taxon. Each taxon contains the organisms in the

taxon below. So, if two organisms are in the same family,

they are also in the same order, class, phylum and kingdom.

Examples and Meanings One great thing about classifying

organisms is that the taxon names have meanings that describe the organisms in those taxa.

The following six slides show the classification of great white sharks, striped bass, the common house fly, the blue crab, chimpanzees and humans.

All are in the Kingdom Animalia (animals). Hopefully you will notice the similarities

and differences contained in the meanings of their scientific names. Enjoy!

Great White SharkKingdom: Animalia Phylum: Chordata Class: Chondrichthyes (fish with cartilage instead of bones)Order: LamniformesFamily: LamnidaeGenus: Carcharodon (“ragged tooth”)Species: carcharias (“shark”)

Striped Bass (Rockfish)Kingdom: AnimaliaPhylum: ChordataClass: Osteichthyes (fish with bones)Order: Perciformes (perch-like fish)Family: Moronidae (temperate basses)Genus: Morone

Species: saxatilis (“dwelling among rocks”)

Common HouseflyKingdom: AnimaliaPhylum: Arthropoda (“jointed foot”)Subphylum: Hexapoda (“six-legged”)Class: InsectaOrder: Diptera (flies with one pair of wings)Family: Muscidae (stocky flies with large eyes)Genus: Musca

Species: domestica (“domestic”)

Blue CrabKingdom: AnimaliaPhylum: ArthropodaSubphylum: Crustacea (lobsters, crabs, shrimp)Class: MalacostracaOrder: Decapoda (“ten legs”)Family: Portunidae (swimming crabs)Genus: Callinectes (“beautiful swimmer”)Species: sapidus (“delicious”)

ChimpanzeeKingdom: AnimaliaPhylum: ChordataClass: MammaliaOrder: PrimatesFamily: Hominidae (great apes and humans)Genus: PanSpecies: troglodytes (“cave man”)

Seems that the scientific name for chimpanzees comes from people originally thinking that chimps looked like “cave men”!!!

HumansKingdom: AnimaliaPhylum: ChordataClass: MammaliaOrder: PrimatesFamily: Hominidae (great apes and

humans)Genus: Homo (“man”)Species: sapiens (“knowing” or “thinking”)

Some questions… Which of the previous organisms is

most closely related to humans?

What is the major difference between the great white shark and the striped bass?

Why are the housefly and blue crab both put into the same Phylum—Arthropoda?

Chimpanzees (they are both in the same family)

Sharks have cartilage and bass have bones

They both have jointed appendages (legs)

Use the information on the next three slides to answer a

few questions HERE.

Black Bear (Ursus americanus) Kingdom—Animalia (multicellular

eukaryotes, no cell walls and heterotrophic) Phylum—Chordata (endoskeleton and a

hollow nerve cord) Class—Mammalia (mammary glands,

endothermic metabolism, hair and specialized teeth)

Order—Carnivora (three pairs of incisors on upper and lower jaws with large canines)

Family—Ursidae (stocky and powerful, densely furred bodies with small ears, closely set eyes and a prominent muzzle)

Red Maple (Acer rubrum)

Kingdom—Plantae (multicellular eukaryotes, autotrophic with cell walls)

Division—Magnoliophyta (vascular tissues, true roots, stems, leaves and flowers; enclosed seeds)

Class—Magnoliopsida (two seed parts) Order—Sapindales Family—Sapindaceae (deciduous,

toothed leaves and winged fruit)

Cyanobacteria (Anabaena spp.)

Kingdom—Bacteria (single-celled prokaryotes that lack membrane-bound organelles)

Division—Cyanophycota (autotrophic with some being nitrogen fixers)

Class—Cyanophyceae Order—Nostocales (filamentous,

motile and reproduce through binary fission)

Family--Nostocaceae

Use the table below to answer a few questions HERE.

Common name

Human Lion House Cat

Kingdom Animalia Animalia AnimaliaPhylum Chordata Chordata ChordataClass Mammalia Mammalia MammaliaOrder Primate Carnivora CarnivoraFamily Homonida

eFelidae Felidae

Genus Homo Panthera Felisspecies sapiens leo domesticu

s

DICHOTOMOUS KEYS

A dichotomous key is a tool used to identify unknown things.

A B DC

Use the following dichotomous key to identify the tools above.

A B DC1a. It requires electricity… Circular saw

1b. It does not require electricity…

Go to 2

2a. It has teeth… Hack saw

2b. It does not have teeth… Go to 3

3a. It has a blunt metal head… Hammer

3b. It has a flat, triangular head… Trowel

A B DCHammer Hack

sawTrowel Circular

saw

How did you figure out the names of these tools?

How to use the dichotomous key

Look at what you are trying to identify (duh!)

Read the description for 1a. If the description doesn’t

match, then go to 1b.Follow the directions until you

find the correct description of your mysterious object!

Bringing It Together Taxonomy is the science of naming

and classifying organisms.

A scientific name contains two Latin or Latinized terms that describe an organism. This is also called binomial nomenclature.

Remember—scientific names are usually descriptive. Domesticus means domestic and Americanus means it is found in America!

Bringing It Together Remember your taxa in order—

• Kingdom• Phylum• Class• Order • Family• Genus• Species

All organisms in one taxon are also in the same taxa above. For example, organisms in the same Order would also be in the same Kingdom, Phylum and Class.

Bringing It Together

Organisms are grouped together based on similarities. For example, fish and birds are in the same kingdom and phylum because they have a backbone and are animals.

A dichotomous key is used to identify things based on their appearances.